Firmware Engineer (Vending Machine Controller Development)

About the role

We are building a custom Vending Machine Controller (VMC) board in collaboration with Riosh Technologies (confirmed board components). You will be the primary firmware engineer responsible for hardware bring-up, motor/elevator control, and the machine UI (touch display). This is a high-impact role — you’ll own the embedded stack for our pilot vending machines and help define firmware standards for future machines.

Key Responsibilities

• Bring up and validate the confirmed VMC board (RPI CM4-based compute / or equivalent module).
• Implement robust firmware for motors, sensors, elevator control, and vending sequences.
• Develop machine-side UI screens (LCD / touch) for vendor flow (welcome, vend, error, OOS, thank you).
• Implement comms & diagnostics (UART/SPI/I²C) and integrate with backend APIs (HTTP/MQTT).
• Implement logging, retry/recovery logic, watchdogs, and OTA-ready hooks.
• Work closely with Riosh (hardware partner) to validate schematics, pinouts, and run prototype tests.
• Provide detailed handover: source code, flashing instructions, PCB pin mapping, and test procedures.
• Provide short-term support (2–4 weeks) for bugs after delivery and assist integration testing.

Confirmed Hardware Components (you will work with)

• Compute Module 4 (RPI CM4 or equivalent) — main processor & Wi-Fi.
• LTE Modem + SIM connector (cellular comms).
• RJ45 ethernet.
• Onboard Flash (storage) and LCD display for UI.
• Temperature sensor, IR sensor, limit switches.
• Motor driver(s) for motors/elevator.
• LEDs & switches for status/config.
• 24VDC power input, surge protection, regulators (3.3V/5V).
• PCB: 2–4 layers, 1.6mm thickness.

(These components are confirmed by our hardware partner — candidate must be comfortable with bringing-up these exact modules.)

Required Skills & Experience

• 3–8+ years in embedded firmware development.
• Strong C/C++ expertise; comfortable with ARM Cortex or RPi CM4 platforms (or ESP32/STM32 if relevant).
• Experience with FreeRTOS or comparable RTOS.
• Experience implementing motor control (DC/stepper), limit switches, IR sensors.
• Experience debugging with logic analyzers/oscilloscopes.
• Comfortable implementing UART/SPI/I²C, ADC, PWM, timers.
• Prior experience integrating cellular/LTE modules, Wi-Fi and ethernet preferred.
• Strong documentation and test case discipline.