Structured firmware
Developing C/C++ firmware for sensor acquisition, state handling, actuator control, persistent settings, watchdogs, and OTA.
Process Engineering · Embedded & IoT
Dhimas ArdinataPutra Pamungkas
Reliable firmware, from device to field.
I work in process engineering at Wiwynn and bring hands-on experience developing embedded firmware and IoT systems, from device integration through field validation.
- C/C++ Firmware
- ESP32 · ESP8266
- RS485 / Modbus RTU
- Wi-Fi / GPRS · OTA
Wiwynn · Senai, Johor, Malaysia
- 7 months
- field IoT implementation
- 3.80/4.00
- Telecommunication Engineering GPA
- 845/990
- TOEIC Listening & Reading
How I work
From device pins to dependable data.
I work on the engineering details that make IoT products practical to operate, maintain, and diagnose when something goes wrong.
Communication integration
Connecting devices and services through RS485/Modbus RTU, UART, I²C, Wi-Fi, GPRS/LTE, and REST.
Field validation
Checking wiring, sensors, power, modems, connectivity, and data flow, then documenting findings and follow-up actions.
Selected work
Embedded and IoT systems I developed.
These four field projects show my hands-on work in firmware, hardware and software integration, and deployment. I also authored and tested a set of Raspberry Pi learning modules.
The field projects cover development through deployment. The Raspberry Pi modules include technical documentation and checks of 11 lab units.
01
Final project • team system for Von Florist (Kendal, Central Java, Indonesia) • 2025-2026
ATOMIC: IoT/WSN Orchid Greenhouse Monitoring & Control
A microclimate monitoring and equipment-control system connecting 10 ESP8266 sensor nodes to 2 ESP32 gateway/controllers and cloud services.
- Developed node firmware to measure temperature, humidity, and light, along with gateway/controller firmware for greenhouse equipment.
- Integrated blower, exhaust fan, and dehumidifier control through relay/SSR and contactor panels, with control thresholds and schedules.
- Implemented node-side store-and-forward caching; calculated cache capacity is about 4.97 days at a 10-minute sampling interval (716 records, 100 KB LittleFS, maximum 143 bytes per record). The system also supports connection recovery, gateway logging, LCD/RTC/SD card, WebSocket diagnostics, and OTA payloads up to 751.7 KB.
- QoS analysis across 10 nodes (25 Feb–31 Mar 2026; 50,400 expected packets) showed telemetry loss fell from 51.98% to 15.45% after node-side store-and-forward caching was introduced; 42–44% of delivered telemetry came through local SD/flash cache.
02
OmahIoT internship project • Salatiga, Central Java, Indonesia • 2025
MONIK: Hydroponic Monitoring & Control
Internship project developing hydroponic monitoring and control firmware, from nutrient-solution and environmental sensing to condition-based pump operation.
- Developed an ATmega328P monitoring unit to read pH, EC/TDS, water and air temperature, humidity, light, nutrient level, RTC, and a Nextion display; telemetry is sent through an ESP8266.
- Developed ESP32 control for nutrient A/B and pH-down pumps, with control thresholds, fail-safes for stale or invalid data, persistent settings, watchdog, reconnection, and OTA.
- Investigated a field pH drop to 2.5, traced it to reversed dosing-pump polarity, and corrected the wiring.
03
OmahIoT internship project • sedimentation & flood monitoring • 2025
MOSIBAN: Rainfall Monitoring Device
An ESP32/TTGO T-Call device that sends tipping-bucket rainfall data to support sedimentation and flood monitoring.
- Implemented hardware-interrupt debouncing for tipping-bucket events, converted tip counts into rainfall measurements, and sent them over HTTP/JSON.
- Integrated SIM800/GPRS and a DS3231 RTC, with Bluetooth Serial diagnostics, connection recovery, and Wi-Fi OTA.
04
Politeknik Negeri Semarang × OmahIoT joint research • outside internship • 2026
IMONIK: Intelligent Monitoring & Controlling for Industrial Hydroponics
Supported firmware development and device validation for joint research by Politeknik Negeri Semarang and OmahIoT on industrial hydroponic monitoring and control.
- Supported ESP32 sensor and control integration over RS485/Modbus RTU and UART/I²C, including the display/RTC, water-level sensor, SIM7600 modem, and pumps.
- Built RS485 test firmware to verify pins and wiring, scan Modbus addresses, and diagnose communication before system integration.
- Contributed to persistent configuration, fault handling, local monitoring, and OTA-based firmware maintenance.
05
Alpro II • Jul-Dec 2025
Raspberry Pi Modules: 22 Guided Lessons
A set of 22 Indonesian-language Raspberry Pi lessons for Algorithms & Programming II, with progress tracking and a path from introductory to advanced topics.
- Authored 22 Indonesian-language lessons with progress tracking for use as course material.
- Basic track: OS, terminal, Python, GPIO, sensors (HC-SR04, LM35, BH1750), I²C/UART, and Blynk dashboard.
- Advanced topics: MQTT/Mosquitto, MariaDB, multi-Pi, hardening, and Flask. Checked 11 Raspberry Pi lab units and documented sensor faults to keep the equipment ready for classes.
Sourcesmateri-raspberrypi-smt7
Measured results from the field
Gateway 1 (GH1)
Gateway 2 (GH2)
Telemetry loss before and after store-and-forward caching • 10 nodes • 50,400 expected packets • 25 Feb–31 Mar 2026.
Open source
Explore the project code.
Alongside two sanitized final-project repositories, I built EAWS and contributed two merged networking fixes to Arduino-ESP32.
ESP32-Greenhouse-Controller
ESP32 gateway/controller firmware for greenhouses. Sanitized public version of the ATOMIC final project.
C++
esp8266-sensor-node
ESP8266 sensor-node firmware for temperature, humidity, and light telemetry.
C++
EAWS v0.5.1
Asynchronous HTTP, WebSocket, and SSE library for ESP8266/ESP32, published through PlatformIO.
C++ · PlatformIO
Arduino-ESP32 Core v3.3.9 · PR #12613
Merged NetworkClient::flush() fix that preserves unread RX data.
Arduino-ESP32 Core v3.3.9 · PR #12615
Merged fix that preserves CA bundle configuration across TLS stop and reconnect flows.
Systems perspective
Validation from sensor to operation.
I consider how physical conditions in the field become control decisions and useful data for operators.
- 01Sensors & actuators
pH/EC, environment, level, relays, pumps
- 02Device buses
RS485, Modbus RTU, UART, I²C, SPI
- 03Control firmware
Acquisition, state, interlocks, cache, faults
- 04Connectivity
Wi-Fi, GPRS/LTE, MQTT, HTTP/REST
- 05Operations
Dashboard, OTA, logging, troubleshooting
Core expertise
Skills developed through hands-on implementation.
Firmware
- C and C++
- Arduino framework
- PlatformIO
- State-based firmware
- Persistent settings
- Local caching
- OTA and watchdogs
- FreeRTOS-based ESP32 firmware
- Zephyr exposure (nRF Connect SDK)
Platforms & hardware
- ESP32 / ESP32-S3
- ESP8266 / Wemos D1 Mini
- TTGO T-Call
- ATmega328P
- Sensors and relay/SSR
- RTC, displays, cellular modems
Device protocols & networking
- RS485
- Modbus RTU
- UART
- I²C
- SPI
- Wi-Fi
- GPRS/LTE
- MQTT
- HTTP/HTTPS and REST
Validation & tools
- Serial monitor
- Multimeter and wiring checks
- Git/GitHub
- Python analysis
- CMake
- Linux/SSH
- Field troubleshooting
- Technical documentation
Experience
Experience in production engineering and hardware development.
Process Engineering Support Technician
Wiwynn
- Support process engineering for hyperscale cloud/AI server lines (L6 PCBA) across SMT and DIP, checking fixture/tool setups and assisting ICT/MDA, BST, and BFT operations.
- Monitor production-line processes, report deviations, and help process engineers follow up on corrective actions.
- Follow ESD, 5S, and standard test procedures, documenting results to support product quality and traceability.
Hardware Development Intern
OmahIoT
- Supported agricultural IoT projects from site surveys through deployment, testing, and documentation. Projects included MONIK in Salatiga, Central Java, Indonesia, and ATOMIC field implementation in Kendal, Central Java, Indonesia, which continued as my final project.
- Developed firmware for ESP32, ESP8266, TTGO T-Call, and ATmega328P devices, covering sensor acquisition, relay and pump control, local displays, and remote telemetry.
- Checked 19 greenhouse nodes in Sumowono, Central Java, Indonesia, before their relocation to Medini, Kendal, Central Java, Indonesia; documented sensor faults and calibrated each node against handheld reference meters.
- Diagnosed 11 lab units and documented per-sensor failure reports to keep the Raspberry Pi lab ready for classes.
- Investigated a field pH drop to 2.5, traced it to reversed dosing-pump polarity, and corrected the wiring.
- Completed the internship with a Very Good rating.
IMONIK research contribution
Outside my internship, I developed and tested firmware for an industrial hydroponic system as part of joint research by Politeknik Negeri Semarang and OmahIoT.
Education
Politeknik Negeri Semarang
B.App.Eng.: Telecommunication Engineering • GPA 3.80/4.00
2022-2026 • Graduated August 2026.Certifications & languages
- Linux Essentials · Cisco Networking Academy (7 Sep 2026)
- SCE Automation Fundamentals (PLC) · Siemens (6 Sep 2026)
- Six Sigma White Belt · CSSC (5 Sep 2026)
- Hardware Components and Troubleshooting · IBM SkillsBuild (25 Aug 2026)
- Information Technology Fundamentals · IBM SkillsBuild (20 Aug 2026)
- C++ Essentials 1 · Cisco Networking Academy (24 Jul 2026)
- nRF Connect SDK Fundamentals · Nordic Semiconductor (12 May 2026)
- CCNA: Switching, Routing and Wireless Essentials (10 Nov 2024)
- TOEIC Listening & Reading 845/990 (tested 16 Nov 2025 · valid until Nov 2027)
- Indonesian · native • English · professional working proficiency · TOEIC 845/990
FAQ
Frequently asked questions
Where are you working now?
I currently work as a Process Engineering Support Technician at Wiwynn in Senai, Johor, Malaysia.
How was the caching improvement measured?
QoS analysis covered 10 nodes from 25 Feb to 31 Mar 2026, with 50,400 expected packets. After node-side store-and-forward caching was introduced, overall telemetry loss fell from 51.98% to 15.45%: from 53.1% to 19.3% on gateway 1 and from 50.9% to 11.6% on gateway 2.
What happens when connectivity is lost?
Nodes store readings locally and forward them when the connection returns. Based on 100 KB of LittleFS and a maximum record size of 143 bytes, the calculated capacity is about 716 records, or 4.97 days at a 10-minute sampling interval. This is a capacity calculation, not a measured outage duration.
How do you troubleshoot RS485/Modbus issues?
I start with separate test firmware to verify the pinout and DE/RE direction, check A/B wiring, and scan Modbus addresses. Then I investigate timeouts, framing, and baud rate before full integration.
What did you contribute to ATOMIC?
ATOMIC was a team final project for Von Florist. I worked on device firmware, node-to-gateway integration, actuator control, connection reliability, and hardware and software validation.
Is the project code available?
Yes. Two final-project repositories are public after credentials and private data were removed: ESP32-Greenhouse-Controller and esp8266-sensor-node.
Let’s connect
Have a firmware or IoT project in mind?
I’m open to collaboration and technical discussions about firmware, IoT, and device integration.