IoT Firmware Engineer (ESP32 · C · Bluetooth LE)

Compensation: full-time employee, indefinite-term contract. COP 6,000,000 to 11,000,000 per month depending on experience and English level, plus all Colombian statutory benefits. 2-month probation.

Location: Medellín, Colombia. Hybrid: 3 days in the office (bench days), 2 from home.

English: B2 or higher, especially reading and writing (docs, datasheets, email with manufacturers), with occasional calls with engineers in the US.

About us

GME International is the technology team of a business group that acquires and runs companies in the US. One of them makes a smart-home hub for recreational vehicles (RVs): our own gateway, with a cellular modem, GPS and Bluetooth, collects data from the vehicle's sensors (tire pressure, doors, water leaks, temperature, propane level, door lock) and sends it to AWS. Users control everything from a mobile app. Units are already in the field. Data privacy and security come first.

The mission

Own the gateway firmware and every sensor that connects to it. The device works in the field, keeps reporting on low battery, updates securely over the air, and adding a new sensor is fast and reliable.

What you'll do

• Take over, maintain and improve the gateway firmware: ESP32, ESP-IDF and FreeRTOS, in C. Stability comes before new features.
• Measure and improve how the device behaves on low battery and within its limits: sleep states, wake-up events, current draw, memory, how many Bluetooth connections it holds at once, and the time from a sensor event to the user's phone.
• Integrate new Bluetooth LE sensors and devices. Reading comes first; two-way control (for example, climate control) follows a safety review.
• Evaluate sensors from outside manufacturers (OEM/ODM, many in Asia): bench-test samples, document their protocol, validate battery life, range and accuracy.
• Work with manufacturers in English on firmware changes and documentation, and check their devices don't send data to third-party clouds.
• Own the device side of the AWS IoT Core link (MQTT, Device Shadow) and signed OTA updates, with staged rollouts and a way back if an update fails. The platform team owns everything after the message reaches AWS; you agree the message format with them.
• Optimize cellular data use.
• Troubleshoot field issues with support and hardware manufacturers.
• Evaluate on the bench how the gateway could read the vehicle's CAN network (RV-C).
• Keep the automated build and the tests working, and document everything so the knowledge stays with the team.

You report to the Tech Lead, who owns the AWS platform. This is a hands-on individual-contributor role, not a team-lead position. You will be the team's only firmware specialist, so you need to work with technical autonomy.

Must-haves

1. 3+ years of embedded C firmware on products in production (not only prototypes).
2. ESP32 and ESP-IDF, or another microcontroller on FreeRTOS or another RTOS (STM32, nRF52, PIC32...).
3. Bluetooth LE in code: GATT, central role, parsing advertisements, writing commands.
4. Finding hard faults on an RTOS: memory corruption, race conditions, stack overflows; reading crash dumps.
5. Low-power firmware on battery-backed devices: sleep states, wake sources, measuring current draw.
6. MQTT from a device to the cloud, over TLS.
7. Bench work (datasheets and schematics, oscilloscope, logic analyzer or BLE sniffer), plus Git and automated builds.
8. B2+ English.

Nice to have

• Strong plus: cellular modems (Quectel or others), AT commands, LTE Cat-1/Cat-4.
• Over-the-air updates delivered to units already with customers.
• CAN bus; RV-C, J1939 or another vehicle protocol.
• AWS IoT Core on the device side: Fleet Provisioning, Device Shadow, Jobs/OTA.
• ESP32 Secure Boot and flash encryption.
• Integrating poorly documented third-party sensors; analysing a device's Bluetooth traffic with a sniffer, with the manufacturer's cooperation.
• Working with manufacturers in Asia (samples, firmware changes).
• Certifications (FCC, PTCRB) or taking a product through a lab.
• GPS.
• Python for test and factory tooling.

How we work

We use AI agents every day, and anything that touches security or goes to units in the field gets human review. Updates reach a small group of devices before the whole fleet, and every change has a way back. You will take over code written by someone else, so your own tests and notes are the team's safety net. Bench work happens in the office: devices, test equipment and source code stay on company equipment.

What we offer

• Full-time indefinite contract with all statutory benefits.
• Health allowance: up to COP 150,000 a month toward a complementary health plan or prepaid medicine, on top of the mandatory EPS, paid against the provider's invoice.
• Compensation review at 6 months based on performance.
• Equipment and a test bench: gateways, sensors, power supply and current meter, logic analyzer and BLE sniffer.
• An IoT product in production with the full codebase in house, in a group growing through acquisitions.
• Candidates elsewhere in Colombia willing to relocate to Medellín are welcome; relocation support negotiable.