Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 229-243
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ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay
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Low-cost embedded architecture for repeatable time control in electronic test
stations
Arquitectura embebida de bajo costo para el control temporal repetible en
estaciones de prueba electrónica
Arquitetura embarcada de baixo custo para o controle temporal repetível em
estações de teste eletrônico
Emiliano Crespo-Torres
1
, René Fernando Domínguez-Cruz
2
, Leopoldo Asael Garza-Alvarado
3
,
Pedro Edén Zamora-González
4
, Yadira Aracely Fuentes-Rubio
5
(*)
Recibido: 16/02/2026 Aceptado: 14/04/2026
Summary. - Automation of electronic test stations is often constrained by manual timing control, which introduces
operator-dependent variability, extended cycle durations, and increased rework. This study presents a low-cost
embedded system for automated and repeatable time control in electronic test stations, designed to ensure consistent
cycle termination, integrated visual feedback, and automatic power disconnection. The proposed architecture is based
on a microcontroller platform implemented with widely available components to guarantee simplicity and scalability.
The system was technically characterized to evaluate timing accuracy, repeatability, and actuation consistency under
real industrial conditions. Experimental results obtained from 120 test cycles over a four-week period show stable
cycle-to-cycle behavior, with a mean cycle time of 30.02 min, a standard deviation of 0.03 min, and a maximum
absolute timing error below 0.08 min relative to the programmed duration. Operational validation showed a reduction
in out-of-time events from 20% to 4%, as well as decreases in rework frequency and station downtime. The results
indicate that the proposed system provides consistent and repeatable timing control at the minute scale, reducing
operator-dependent variability while maintaining lower complexity and cost than conventional industrial automation
platforms.
Keywords: Repeatable time control; Embedded systems; Electronic test stations; Industrial automation; Low-cost
systems.
(*) Corresponding author.
1
B.Eng. in Electronics Engineering. Electronics Department. Universidad Autónoma de Tamaulipas (Mexico);
a2213720038@alumnos.uat.edu.mx; ORCID iD: https://orcid.org/0009-0006-0397-7767
2
PhD. Electronics Department. Universidad Autónoma de Tamaulipas (Mexico);
rfdominguez@docentes.uat.edu.mx; ORCID iD: https://orcid.org/0000-0001-7001-7543
3
PhD. Electronics Department. Universidad Autónoma de Tamaulipas (Mexico);
leopoldo.garza@docentes.uat.edu.mx; ORCID iD: https://orcid.org/0000-0002-7760-2718
4
M.Sc. Electronics Department. Universidad Autónoma de Tamaulipas (Mexico);
pzamora@docentes.uat.edu.mx; ORCID iD: https://orcid.org/0000-0002-8469-9896
5
PhD. Electronics Department. Universidad Autónoma de Tamaulipas (Mexico);
yfuentes@docentes.uat.edu.mx; ORCID iD: https://orcid.org/0000-0002-7385-9794
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 229-243
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Resumen. - La automatización de estaciones de prueba electrónica suele verse limitada por el control manual del
tiempo, lo que introduce variabilidad dependiente del operador, prolongación de ciclos y aumento de reprocesos. Este
trabajo presenta un sistema embebido de bajo costo para el control temporal automatizado y repetible en estaciones
de prueba, diseñado para garantizar la terminación consistente de ciclos, retroalimentación visual integrada y
desconexión automática de energía. La arquitectura propuesta se basa en una plataforma de microcontrolador
implementada con componentes ampliamente disponibles para asegurar simplicidad y escalabilidad. El sistema fue
caracterizado técnicamente para evaluar precisión temporal, repetibilidad y consistencia de actuación en condiciones
industriales reales. Los resultados experimentales obtenidos a partir de 120 ciclos de prueba durante cuatro semanas
muestran comportamiento estable entre ciclos, con tiempo promedio de 30.02 min, desviación estándar de 0.03 min y
un error absoluto máximo inferior a 0.08 min respecto al valor programado. La validación operativa evidenció una
reducción en eventos fuera de tiempo del 20% al 4%, así como disminuciones en la frecuencia de reprocesos y en los
tiempos muertos de la estación. Los resultados indican que el sistema propuesto proporciona un control temporal
consistente y repetible a escala de minutos, reduciendo la variabilidad dependiente del operador, mientras mantiene
menor complejidad y costo que las plataformas de automatización industrial convencionales.
Palabras clave: Control temporal repetible; Sistemas embebidos; Estaciones de prueba electrónica; Automatización
industrial; Sistemas de bajo costo.
Resumo. - A automação de estações de teste eletrônico é frequentemente limitada pelo controle manual do tempo, o
que introduz variabilidade dependente do operador, aumento da duração dos ciclos e retrabalho. Este trabalho
apresenta um sistema embarcado de baixo custo para o controle temporal automatizado e repetível em estações de
teste, projetado para garantir a terminação consistente dos ciclos, retroalimentação visual integrada e desligamento
automático de energia. A arquitetura proposta baseia-se em uma plataforma de microcontrolador implementada com
componentes amplamente disponíveis, assegurando simplicidade e escalabilidade. O sistema foi caracterizado
tecnicamente para avaliar a precisão temporal, a repetibilidade e a consistência de atuação em condições industriais
reais. Os resultados experimentais obtidos a partir de 120 ciclos de teste ao longo de quatro semanas demonstram
comportamento estável entre ciclos, com tempo médio de 30.02 min, desvio padrão de 0.03 min e erro absoluto máximo
inferior a 0.08 min em relação ao valor programado. A validação operacional evidenciou redução nos eventos fora
do tempo de 20% para 4%, bem como diminuições na frequência de retrabalho e no tempo de parada da estação. Os
resultados indicam que o sistema proposto fornece controle temporal consistente e repetível na escala de minutos,
reduzindo a variabilidade dependente do operador, ao mesmo tempo em que mantém menor complexidade e custo em
comparação com plataformas industriais convencionais.
Palavras-chave: Controle temporal repetível; Sistemas embarcados; Estações de teste eletrônico; Automação
industrial; Sistemas de baixo custo.
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
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1. Introduction. - In the electronics manufacturing industry, board testing is a critical step in ensuring the quality and
reliability of devices. However, many companies still rely on manual timers for this procedure, which introduces high
variability and recurring errors. Manual initiation and termination of tests by operators can lead to delays in board
removal, overexposure of modules, and, consequently, rework or scrap. These limitations negatively impact operational
efficiency, increase production costs, and reduce process traceability [1-3].
Several studies have shown that automating repetitive operations at test stations can standardize procedures, minimize
human error, and increase productivity [4, 5]. In the domain of electronic board validation testing, in-circuit testing
(ICT) employing bed-of-nails equipment and flying-probe systems has become a prevalent method for automating
signal acquisition and verifying internal connections. The bed-of-nails method facilitates the concurrent measurement
of multiple variables, rendering it highly conducive to mass production. On the other hand, the flying-probe method is
distinguished by its adaptability, enabling expeditious adjustments without necessitating the fabrication of specialized
equipment [6]. However, the testing process is often characterized by a reduction in efficiency, attributable to the
sequential movement of the probes. [6, 7]. This scenario has motivated the development of low-cost alternatives,
particularly those based on open platforms such as Arduino, which have proven effective in building programmable,
accessible, and adaptable test equipment for different industrial contexts. [8-10].
In parallel, the Lean Manufacturing philosophy emphasizes the importance of tools such as Poka-yoke, visual
management, and Andon systems to prevent errors and ensure the standardization of processes [11-13]. In this sense,
the integration of microcontrollers with visual and audible alerts constitutes a solution aligned with these practices,
particularly in manufacturing environments where cost margins are reduced and technological flexibility is required
[9, 14].
This paper presents a proposal to solve the problem of manual time control in electronic test stations on a maquiladora
production line in Mexico. A low-cost automated system based on an Arduino microcontroller, relays, and digital
displays was designed and validated with the goal of reducing variability in test cycles and decreasing errors associated
with manual supervision. The development included stages of diagnosis, design, simulation, prototype construction,
and on-site testing, yielding significant results: a reduction in out-of-time cards from 20% to 4%, a decrease in weekly
rework from 9 to 2 units, and an estimated reduction in monthly scrap from USD 14,400 to USD 3,200.
The proposal also aligns with the Sustainable Development Goals (SDGs) of the 2030 Agenda [15]. It contributes to
SDG 9 (Industry, innovation and infrastructure) by promoting the use of accessible and scalable technologies that
foster innovation in production processes. It also impacts SDG 12 (Responsible production and consumption) by
reducing material waste and scrap costs, strengthening resource efficiency, and the sustainability of manufacturing.
Finally, the system is designed with scalability in mind: it could be integrated with data logging modules, graphical
interfaces for centralized monitoring, connectivity with industrial-grade (IoT) systems, or analysis tools that facilitate
continuous process improvement. In this way, the project not only solves a specific problem in the test line but also
lays the foundation for sustainable and efficient modernization of operations in the electronics industry.
Technical novelty and contribution. - Unlike commercial low-cost timing solutions commonly used in electronic
test stations, such as standalone timers, manual countdown devices, or simple relay-based controllers without feedback,
these systems typically lack deterministic actuation, integrated visual feedback, and cycle-level repeatability. As a
result, they do not prevent timing deviations caused by delayed operator intervention and provide limited support for
process standardization.
The technical contribution of this work lies in the development of a deterministic, microcontroller-based time control
architecture that integrates countdown visualization, automatic power disconnection, and operator acknowledgment
into a single low-cost embedded system. Although the proposed solution does not target high-precision industrial
control applications, it introduces repeatable and reliable cycle-level timing control using widely available components,
bridging the gap between manual timing practices and high-cost industrial automation platforms.
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
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This architecture represents an incremental yet practical advancement over existing low-cost solutions by ensuring
consistent test cycle termination, minimizing operator-dependent variability, and enabling scalability to multiple test
stations within resource-constrained manufacturing environments.
In this work, the term “deterministic time control” is used in an operational sense, referring to consistent and repeatable
cycle termination at the minute scale under fixed conditions, rather than strict real-time determinism with bounded
microsecond-level latency. This distinction is relevant given the application context, where robustness and repeatability
over long-duration cycles are prioritized over high-frequency temporal precision.
2. Materials and Methods. - The design and implementation of an automated time control system for electronic test
stations were carried out at an electronics manufacturing company located in Mexico. The study was conducted using
an applied and quantitative approach, aimed at solving a real-world problem in the field of electronic board testing.
The methodology was organized into five phases: process diagnosis, requirements definition, design and simulation,
prototype construction, and validation in a real-world environment.
2.1. Analysis of the current process. - Process diagnosis is the first methodological step and aims to understand how
the electronic card testing operation is currently performed, identifying weaknesses and areas for improvement. This
analysis allows for documentation of the activities performed by personnel, the time involved, and the risks associated
with manual process management. This establishes a baseline that will serve as a point of comparison for later
evaluating the impact of the automated solution.
Under the current system, test time control is manual and non-standardized. The station manager must load modules
into the test equipment, start the count independently (clock/stopwatch), perform other parallel tasks, and return to
retrieve the module upon completion. The nominal programmed time per module is 30 minutes. However, due to
operator multitasking and delayed module retrieval, the actual cycle time typically increases to 35–40 minutes under
manual operation. This discrepancy between programmed and real cycle time leads to inefficiencies, increased
downtime, and a higher probability of overexposure-related defects.
Furthermore, the lack of a visual or audible alert system at the end of the cycle increases the likelihood that cards will
remain at the station longer than required. This not only affects traceability and process consistency but can also lead
to rework, material waste, and operator overload. The diagram in Figure I shows the current process flow (before
automation).
Figure I. Diagram of the current process.
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
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To establish the baseline, the following indicators were measured (Table I):
Indicator
Before improvement
Programmed cycle time
30 min
Actual cycle time
35–40 min
Percentage of delayed/out-of-time cards
20 %
Downtime per test station (due to failure to remove the product)
~40 min/day
Rework due to timing errors
8-9 units/week
Cost of rework or scrap generated by overexposure
~14,400 USD per month
Manual supervision costs (man-cost)
~$6,250 per month
Table I. Definition of base indicators after performing the analysis of the current process.
2.2. Definition of requirements. -In this stage, the functional and technical criteria that the automated system must
meet are established. The purpose of defining requirements is to translate the needs identified in the current process
diagnosis into clear and measurable specifications that guide the design, construction, and validation of the prototype.
This ensures that the system fulfills its primary function of reliably controlling test time, reducing dependence on
manual supervision, and guaranteeing operational efficiency.
2.2.1 General system specifications. -In this stage, the general specifications of the system are established, and the
following are defined:
• Number of stations: The system was initially designed to operate in one test station, with the ability to expand
to eight independent slots. Each slot operates autonomously, allowing simultaneous testing on different
modules without interference.
• Test cycle duration: Each cycle will have a fixed duration of 30 minutes, starting automatically when the
operator presses the start button corresponding to the slot in use.
• Alerts and notifications:
o Visuals: Through a screen, showing the remaining time at each station.
o Automatic actions:
▪ Timer activation by pressing the start button.
▪ Automatic voltage cutoff via a relay at the end of the test cycle.
▪ Visual alert status maintained until the operator confirms module removal.
• These criteria prioritize the use of low-cost components, wide availability, and easy integration into industrial
environments.
2.3. System design and simulation. -The design was structured around an Arduino microcontroller, responsible for
managing timers, displays, and relays. The overall architecture included:
• Inputs: Normally open (NO) pushbuttons associated with each station.
• Control unit: Arduino programmed in the Arduino IDE®.
• Outputs: TM1637 displays, 5V relays, and visual alerts.
The principle of operation of the system can be represented by the following block diagram in Figure II.
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
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Figure II. Block diagram of the proposed automated system.
To validate the design before its physical implementation, two complementary simulation platforms were used:
1. Proteus® Simulation: The complete electronic schematic was developed with up to eight test stations in
parallel (Figure III). This simulation verified pin assignments, the interconnection of multiple displays and
relays, and the feasibility of scaling the system to different test modules.
Figure III. Simulation of the electronic schematic in Proteus®, showing the general diagram with
multiple test stations.
2. Wokwi® Simulation: A simplified model was developed with a single test station, allowing for dynamic
observation of the timer behavior and relay activation in real time (Figure IV). During the simulation, the
automatic start of the cycle upon pressing the button, the countdown on the screen, the deactivation of the
relay at the end of 30 minutes, and the reset in case of early button release were verified.
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
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a)
b)
c)
Both simulations complemented the design process: Proteus® validated the system's scalability with multiple stations,
while Wokwi® confirmed the functional logic in an interactive environment. These results provided confidence to
advance to the physical prototype construction phase, reducing the risk of implementation failures.
2.4 Control algorithm. - The control logic implemented in the microcontroller follows a simple state-based sequence
to ensure consistent and repeatable operation of the test cycle:
1. System initializes in idle state with relay OFF and display inactive.
2. The system waits for the operator to press the START button.
3. Upon activation, the timer is initialized to the programmed value (30 minutes).
4. The relay is activated, supplying power to the test station.
5. The countdown is displayed in real time on the TM1637 display.
6. During the countdown, the system continuously updates the display and maintains relay activation.
7. When the timer reaches zero, the relay is deactivated, interrupting the power supply.
8. A visual alert is activated to indicate cycle completion.
9. The system waits for operator acknowledgment (module removal).
10. Once acknowledged, the system resets to the initial idle state.
This simple control strategy ensures reliable cycle execution while minimizing software complexity, making it suitable
for low-cost embedded implementations.
2.5. Assembly of the prototype. -The prototype was assembled in a mechanically robust metal enclosure suitable for
factory use. The main components are listed in Table II.
Component
Model / Specification
Description
Microcontroller
Arduino Mega (ATmega2560 R3)
Main control unit
Display
TM1637 4-digit LED
Time visualization
Relay module
SRD-05VDC-SL-C
5V, 10A switching capacity
Power supply
5V DC regulated
System power
Inputs
NO push buttons
User activation
Table II. Hardware and system specifications
The relay module includes a flyback diode for transient suppression. The system was designed to ensure a safe default
state, where power is disconnected in case of system reset or failure. Basic debounce logic was implemented in software
to prevent unintended multiple activations.
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
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The display and relay modules were soldered, and an operator-accessible front panel was implemented. The code
loaded into the Arduino controlled the 30-minute timer, relay outputs, and visual signals (Figure Va).
a)
b)
Figure V. a) Assembly of the prototype on a test bench, demonstrating the integration of multiple
displays and relays. b) Installation of the prototype in the production line's test cabinet.
2.6. Validation in a real environment. -The prototype was installed at a station on the company's test line, operating
in parallel with the manual system without interfering with normal operations (Figure Vb). During validation, the same
indicators as the initial diagnosis were recorded, and the results before and after implementation were compared.
In addition to the quantitative data, feedback was collected from the operators, who highlighted the ease of use, the
clarity of the visual signals, and the reduced need for constant supervision. Among the recommendations was the future
incorporation of audible alerts for high-workload environments.
2.7. System performance characterization. -To complement the operational validation carried out in the production
line, a technical characterization of the automated time control system was performed to evaluate its temporal
accuracy, repeatability, and actuation response. This characterization aims to assess the suitability of the proposed
low-cost embedded architecture for reliable operation in industrial testing environments.
2.7.1. Experimental setup and procedure. -The performance evaluation focused on the timing behavior of a single
test station operating under nominal conditions. The programmed test cycle duration was fixed at 30 minutes, as
required by the production process. The system was evaluated over a series of repeated test cycles conducted during
normal operation, ensuring that measurements reflected realistic working conditions.
An external digital chronometer with second-level resolution was used as a reference to measure the actual duration
of each automated test cycle. The start time was recorded at the moment the operator pressed the activation button,
and the end time was recorded when the relay disconnected the power supply to the test module. The difference
between the programmed duration and the measured duration was used to calculate the absolute timing error for each
cycle.
In addition, the response time of the relay actuation was evaluated qualitatively by observing the transition between
the end of the countdown on the display and the physical interruption of the electrical supply to the test fixture.
Although the relay switching time is negligible compared to the total cycle duration, its consistency was verified to
ensure deterministic system behavior.
A total of n = 120 test cycles were analyzed over multiple working days. To reduce measurement bias, the timing data
were recorded using an external digital chronometer operated independently from the system operator. Measurements
were performed consistently following the same procedure, and deviations introduced by human reaction time were
considered negligible compared to the total cycle duration.
The collected data were used to compute average cycle duration, absolute timing error, and standard deviation.
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
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2.7.2. Performance metrics. -The following metrics were considered for system characterization:
• Programmed cycle time (Tₚ): fixed at 30 minutes.
• Measured cycle time (Tₘ): actual duration recorded using the external chronometer.
• Absolute timing error (ΔT): defined as |Tₘ − Tₚ|.
• Cycle-to-cycle variability: evaluated through the standard deviation of Tₘ.
• Actuation consistency: qualitative assessment of relay switching at the end of each cycle.
These metrics provide a quantitative basis for evaluating the reliability and repeatability of the proposed system, which
are critical requirements for automation solutions in electronic testing processes.
2.7.3. Discussion of characterization results. -The characterization results indicate that the automated system
maintains a stable and repeatable timing behavior across repeated cycles. The observed timing deviations remained
small relative to the total test duration, confirming that the microcontroller-based architecture is suitable for long-
duration industrial test cycles where minute-level accuracy is required rather than high-frequency synchronization.
The low cycle-to-cycle variability demonstrates that the system effectively eliminates the timing dispersion associated
with manual supervision, which was identified as a major source of process inefficiency during the diagnostic phase.
Furthermore, the consistent relay actuation at the end of each cycle ensures reliable power disconnection, preventing
test overexposure and reinforcing process standardization.
Although the proposed solution does not aim to replace high-end industrial controllers in applications requiring
millisecond-level precision, its performance is adequate for electronic board testing operations, where robustness,
repeatability, and cost-effectiveness are the primary design constraints. This technical characterization supports the
scalability of the system to multiple stations and its potential integration with additional monitoring or data logging
modules in future developments.
Table III summarizes the main technical performance metrics obtained during the characterization of the automated
time control system. The results confirm stable and repeatable timing behavior, with minimal deviation relative to the
programmed test duration and consistent relay actuation across all evaluated cycles.
Parameter
Symbol
Value
Unit
Description
Programmed cycle time
Tₚ
30.0
min
Fixed test duration defined by process
requirements
Mean measured cycle
time
T
ₘ
30.02
min
Average duration measured using an external
chronometer
Standard deviation of
cycle time
σ
0.03
min
Cycle-to-cycle variability over repeated tests
Maximum absolute
timing error
ΔTₘₐₓ
0.08
min
Maximum deviation between the programmed
and measured time
Relative timing error
εᵣ
0.27
%
Ratio between absolute error and programmed
cycle time
Relay actuation latency
τᵣ
< 1
s
Delay between the end of the countdown and
the power disconnection
Evaluated test cycles
n
120
cycles
Total number of cycles analyzed during
characterization
Operating environment
Industrial
shop
floor
Normal production conditions
Table III. Technical characterization of the automated time control system
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
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3. Results. -The results presented in this section correspond to data collected over a four-week evaluation period,
during which a total of n = 120 test cycles were monitored for a single electronic test station operating under normal
production conditions. All indicators were calculated as average values over the evaluation period, unless otherwise
stated. This dataset provides a representative basis for assessing the operational impact of the proposed automated time
control system under real industrial conditions.
The validation of the automated time control system was carried out on the maquiladora company's electronic card
testing line, using the indicators defined in the diagnostic phase as a baseline for comparison.
An improvement was observed in operations after the prototype implementation (Table IV). The percentage of out-of-
time cards decreased from 20% (baseline average) to 4% (post-automation average) over the evaluation period,
indicating a substantial reduction in timing deviations. Rework attributable to timing-related errors decreased from 8–
9 units per week (baseline range) to 1–2 units per week (post-automation range) during the monitored period.
Furthermore, daily downtime per station was reduced from 40 ± 5 min/day under manual supervision to 10 ± 2 min/day
after automation, reflecting improved consistency in module removal at the end of each test cycle.
In addition to mean and standard deviation, the observed cycle time ranged between 29.96 min and 30.08 min,
indicating low dispersion. A 95% confidence interval for the mean cycle time was estimated as 30.02 ± 0.01 min,
supporting the stability of the system.
Indicator
Before improvement
After improvement
Programmed cycle time
30 min
30 min
Actual cycle time per card
35–40 min
30 ± 1 min
% of cards delayed/out of time
20%
4%
Downtime per station
40 ± 5 min/day
10 ± 2 min/day
Rework due to timing errors
8–9/week
1–2/week
Cost per rework or scrap
~USD 14,400/month
~USD 3,200/month
Cost of manual supervision
~USD 6,250/month
~USD 6,250/month
Table IV. Comparison of indicators before and after the automated system's implementation.
In economic terms, the cost per scrap generated due to electrical overexposure was reduced from approximately USD
14,400 to USD 3,200 per month, representing a savings of more than 75%. Furthermore, the cost of manual supervision
remained constant at approximately USD 6,250 per month, as personnel were able to redistribute their workload
without the need to bring in additional resources.
The cost estimations were based on internal production records, considering the average number of defective units,
unit cost per board, and frequency of rework events. While external factors may influence these values, the comparison
was performed under similar production conditions before and after implementation.
To facilitate the comparative interpretation of the operational improvements obtained after implementing the
automated system, Figure VI summarizes the percentage variation observed for each evaluated indicator. Representing
the results on a unified scale allows direct visualization of the relative impact across performance metrics, highlighting
reductions in delayed cards, station downtime, rework events, and scrap-related costs. This graphical representation
complements the numerical data presented in Table IV and supports the assessment of system effectiveness under real
operating conditions.
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 229-243
https://doi.org/10.36561/ING.30.15
ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 239
Figure VI. Percentage improvement for each operational indicator after implementation of the
automated system.
Feedback from operating personnel indicated that the system was intuitive and easy to use, requiring minimal training.
The screens clearly displayed the times, even in variable lighting conditions throughout the plant. Operators highlighted
the usefulness of the visual signals for identifying modules under test and those completed, suggesting the addition of
audible alerts as an improvement for environments with a higher workload.
The data confirms that the system met its objective of standardizing test cycles to 30 minutes, significantly reducing
variability and deviations compared to the manual process. The reduction in downtime and scrap demonstrates a
positive impact on both operational efficiency and the economic sustainability of the process. These results support
the feasibility of scaling the solution to multiple stations and integrating it with more advanced recording and
monitoring platforms, thus strengthening the company's continuous improvement goals.
4. Discussion. -The results obtained in this study demonstrate that the automation of time control in electronic test
stations can be effectively achieved using a low-cost embedded architecture, while maintaining reliable and repeatable
operation under real industrial conditions. The reduction in out-of-time test cycles, rework frequency, and operational
downtime confirms that the proposed system successfully addresses one of the main sources of variability identified
during the diagnostic phase: operator-dependent timing control.
From a technological standpoint, the primary contribution of this work lies in the integration of deterministic cycle
termination, visual countdown feedback, and automatic power disconnection within a single microcontroller-based
system. Unlike commonly used low-cost commercial solutions—such as standalone timers or manual relay
controllers—the proposed architecture ensures consistent test cycle completion independent of operator availability or
workload. This characteristic is particularly relevant in manufacturing environments where test cycles span several
minutes, and human supervision cannot be continuously guaranteed.
The technical characterization presented in Section 2.7 confirms that the system exhibits stable timing behavior with
minimal cycle-to-cycle variability. Although the proposed solution does not aim to achieve high-frequency or
millisecond-level precision, the observed timing accuracy is sufficient for electronic board testing applications, where
robustness and repeatability at the minute scale are more critical than fine temporal resolution. In this context, the
performance achieved by the microcontroller-based system represents a practical balance between functionality and
cost, making it suitable for deployment in resource-constrained manufacturing settings.
Cycle Time
Delayed cards
Downtime
Reworks errors
Scrap cost
Supervision cost
0
10
20
30
40
50
60
70
80
90
Improvement (%)
Indicator
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 229-243
https://doi.org/10.36561/ING.30.15
ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 240
Compared to industrial-grade automation platforms such as PLC or SCADA-based solutions, the proposed system
offers a significantly lower implementation cost and reduced integration complexity. While high-end platforms provide
advanced communication, diagnostics, and safety features, they are often economically unjustifiable for simple timing
control tasks in small or medium-scale production lines. The presented architecture fills this gap by providing a scalable
and replicable embedded alternative that can be extended to multiple test stations without substantial additional
investment.
From a safety perspective, the system incorporates basic protection mechanisms, including flyback diodes for relay
protection and a fail-safe logic that defaults to power disconnection in case of system reset. However, for large-scale
industrial deployment, additional considerations such as electromagnetic compatibility (EMC), certified switching
components, and compliance with industrial safety standards should be addressed. A basic watchdog strategy can be
implemented to ensure automatic system recovery in case of microcontroller malfunction.
From an operational perspective, the results indicate that standardizing test cycle duration through automated control
contributes not only to improved productivity but also to enhanced process consistency. The elimination of delayed
module removal reduces unnecessary electrical overexposure, directly impacting rework and scrap generation. These
findings support the premise that targeted automation of specific process bottlenecks can yield measurable benefits
without requiring full system overhauls.
The proposed system also presents opportunities for future technological extension. Its modular design allows for the
integration of data logging modules, communication interfaces, or Industrial Internet of Things (IIoT) connectivity,
which would enable real-time monitoring and historical analysis of test performance. Such extensions could facilitate
predictive maintenance, traceability enhancement, and further process optimization. However, these features were
intentionally excluded from the current implementation to preserve system simplicity and cost-effectiveness.
Certain limitations of the present study should be acknowledged. The system was validated in a single test station, and
although the design supports scalability, large-scale deployment may require additional considerations related to
electromagnetic compatibility, industrial safety standards, and integration with existing control infrastructures.
Furthermore, while the relay-based actuation proved reliable for the evaluated application, more demanding electrical
loads may require alternative switching elements.
Finally, while the reduction of scrap and rework contributes indirectly to sustainability objectives by minimizing
material and energy waste, this study does not quantify environmental impact through formal life cycle assessment
methods. Future research could extend the presented work by incorporating environmental performance metrics, as
well as by exploring hybrid architectures that combine low-cost embedded control with higher-level industrial
supervision systems.
5. Conclusions. -The results obtained in this study indicate that, under the evaluated conditions and time frame, the
proposed system provides consistent and repeatable timing control, reducing operator-dependent variability and
improving process standardization. The proposed system effectively eliminated operator-dependent timing variability
by integrating deterministic cycle termination, visual countdown feedback, and automatic power disconnection within
a single microcontroller-based solution.
The technical characterization confirmed stable and repeatable timing behavior across repeated cycles, with minimal
deviation relative to the programmed test duration. Although the system does not target high-precision industrial
control, its performance is sufficient for electronic testing applications where minute-level accuracy, robustness, and
repeatability are the primary requirements.
From an engineering perspective, the main contribution of this study lies in bridging the gap between manual timing
practices and high-cost industrial automation platforms. Compared to commonly used low-cost commercial timers, the
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 229-243
https://doi.org/10.36561/ING.30.15
ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 241
proposed architecture provides deterministic actuation and integrated feedback, while remaining significantly simpler
and more economical than PLC or SCADA-based solutions.
The operational results obtained under real production conditions support the technical findings, showing consistent
reductions in timing-related errors, rework, and downtime. These improvements confirm that targeted automation of
specific process bottlenecks can yield measurable benefits without requiring full system replacement.
Future work will focus on extending the proposed architecture through data logging, communication interfaces, and
scalability assessment across multiple stations, as well as evaluating compliance with industrial safety and
electromagnetic compatibility standards for large-scale deployment.
Funding. - This research was partially funded by Secretaría de Investigación y Posgrado, Universidad Autónoma de
Tamaulipas, by internal grant UAT/SIP/PIRP/2025/088 and the UAM Reynosa-Rodhe Operational Plan 2025 (POA).
Conflicts of Interest. - The authors declare no conflict of interest.
Data availability statement. - All data that support the findings of this study are included within the article (and any
supplementary files).
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 229-243
https://doi.org/10.36561/ING.30.15
ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 242
References
[1] C.-F. Chien and H.-J. Wu, "Integrated circuit probe card troubleshooting based on rough set theory for advanced
quality control and an empirical study," Journal of Intelligent Manufacturing, vol. 35, no. 1, pp. 275-287, 2024/01/01
2024.
[2] S. Verma and N. M. Wagdarikar, "Automated test jig for refrigerator PCB performance," in 2016 International
Conference on Automatic Control and Dynamic Optimization Techniques (ICACDOT), 2016, pp. 840-843.
[3] S. J. Hong, W. Y. Lim, T. Cheong, and G. S. May, "Fault Detection and Classification in Plasma Etch Equipment
for Semiconductor Manufacturing $e$-Diagnostics," IEEE Transactions on Semiconductor Manufacturing, vol. 25, no.
1, pp. 83-93, 2012.
[4] R. Parasuraman, T. B. Sheridan, and C. D. Wickens, "A model for types and levels of human interaction with
automation," IEEE Trans Syst Man Cybern A Syst Hum, vol. 30, no. 3, pp. 286-97, May 2000.
[5] L. Onnasch, C. D. Wickens, H. Li, and D. Manzey, "Human performance consequences of stages and levels of
automation: an integrated meta-analysis," (in eng), Hum Factors, vol. 56, no. 3, pp. 476-88, May 2014.
[6] S. L. Jurj, R. Rotar, F. Opritoiu, and M. Vladutiu, "Affordable Flying Probe-Inspired In-Circuit-Tester for Printed
Circuit Boards Evaluation with Application in Test Engineering Education," in 2020 IEEE International Conference
on Environment and Electrical Engineering and 2020 IEEE Industrial and Commercial Power Systems Europe (EEEIC
/ I&CPS Europe), 2020, pp. 1-6.
[7] N. Petkov and M. Ivanova, "Printed circuit board and printed circuit board assembly methods for testing and visual
inspection: a review," Bulletin of Electrical Engineering and Informatics, vol. 13, no. 4, pp. 2566-2585, 2024.
[8] G. N. Meloni, "Building a Microcontroller Based Potentiostat: A Inexpensive and Versatile Platform for Teaching
Electrochemistry and Instrumentation," Journal of Chemical Education, vol. 93, no. 7, pp. 1320-1322, 2016/07/12 2016.
[9] F. J. Jiménez-Romero, J. R. González-Jiménez, F. García-Torres, Á. Caballero, and F. R. Lara-Raya, "A novel
testing equipment based on Arduino and LabVIEW for electrochemical performance studies on experimental cells:
Evaluation in lithium-sulfur technology," Measurement, vol. 224, p. 113922, 2024/01/01/ 2024.
[10] E. Hernández-Rodríguez et al., "Reliability Testing of a Low-Cost, Multi-Purpose Arduino-Based Data Logger
Deployed in Several Applications Such as Outdoor Air Quality, Human Activity, Motion, and Exhaust Gas
Monitoring," vol. 23, no. 17, p. 7412, 2023.
[11] S. Shingo, Zero Quality Control: Source Inspection and the Poka-Yoke System. Taylor & Francis, 1986.
[12] J. K. Liker, The Toyota Way: 14 Management Principles From the World's Greatest Manufacturer. McGraw Hill
LLC, 2003.
[13] I.-C. Enache, O. R. Chivu, A.-M. Rugescu, E. Ionita, and I. V. Radu, "Reducing the Scrap Rate on a Production
Process Using Lean Six Sigma Methodology," vol. 11, no. 4, p. 1295, 2023.
[14] J. L. García-Alcaraz, A. S. Morales García, J. R. Díaz-Reza, E. Jiménez Macías, C. Javierre Lardies, and J. Blanco
Fernández, "Effect of lean manufacturing tools on sustainability: the case of Mexican maquiladoras," Environmental
Science and Pollution Research, vol. 29, no. 26, pp. 39622-39637, 2022/06/01 2022.
[15] United Nations. (2024, Octuber 1st, 2024). Sustainable Development Goals of the 2030 Agenda. Available:
https://sdgs.un.org/goals
E. Crespo-Torres, R. F. Domínguez-Cruz, L. A. Garza-Alvarado, P. E. Zamora-González, Y. A. Fuentes-Rubio
Memoria Investigaciones en Ingeniería, núm. 30 (2026). pp. 229-243
https://doi.org/10.36561/ING.30.15
ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 243
Author contribution:
1. Conception and design of the study
2. Data acquisition
3. Data analysis
4. Discussion of the results
5. Writing of the manuscript
6. Approval of the last version of the manuscript
E.C-T has contributed to 1, 2, 3 and 6.
R.F.D-C has contributed to 2, 3, 4, 5 and 6.
L.A.G-A has contributed to 1, 2, 3, 4, 5 and 6.
P.E.Z-G has contributed to 1, 2, 3, 4, 5 and 6.
Y.A.F-R has contributed to 1, 2, 4, 5 and 6.
Acceptance Note: This article was approved by the journal editors Dr. Rafael Sotelo and Mag. Ing. Fernando A.
Hernández Gobertti.