Wearable IoT Device – Firmware, SIM7000G (LTE + GNSS), RF Tuning & System Validation

Project Overview
We have completed the full hardware design and PCB layout of a wearable IoT device and are seeking an experienced embedded systems engineer to continue development.

The PCB is already:
-Fully designed
-Fabricated and assembled
-4-layer, production-grade layout
Your focus will be board bring-up, firmware completion, RF tuning, and system testing.

Hardware Summary
-MCU: nRF52840 (BLE)
-Cellular + GNSS: SIMCOM SIM7000G
(LTE Cat-M / NB-IoT + GNSS in one module)
-Sensors:
oIMU (motion, posture, activity)
oPPG (heart rate, HRV, respiration)
oTemperature

Power:
- Li-Polymer battery
- Dedicated high-current buck for SIM7000G

PCB:
- 4-layer controlled impedance
- Separate LTE, GNSS, and BLE antennas
- RF matching networks included

Scope of Work
Phase 1 — Board Bring-Up
Power rail validation
Flash bring-up firmware
Sensor validation
SIM7000G LTE attach
BLE advertising and data logging

Phase 2 — Firmware Development
Sensor drivers (IMU, PPG, Temp, GNSS)
BLE GATT services (JSON packets)
Power management & sleep modes
SIM7000G LTE data transmission
Sensor + GNSS scheduling logic

Phase 3 — RF Tuning
LTE antenna tuning
GNSS antenna tuning
BLE antenna verification
EMI troubleshooting if required

Phase 4 — Testing & Documentation
BLE range test
GNSS TTFF & accuracy
LTE attach & data test
Battery runtime test
Demo video + documentation
Required Skills
Embedded C/C++ (nRF52 preferred)
BLE GATT services
SIM7000G AT commands
RF antenna tuning (VNA)
Power integrity debugging
Wearable / IoT experience

Deliverables
-Fully working firmware
-Tuned RF matching values
-Test reports
-JSON BLE data logs
-Demo video

Important Notes
-No PCB redesign required
-All schematics, PCB files, BOM, and documentation provided
-Previous engineer available for limited handover support

Project Status
Hardware design completed through Gerber release and PCBA assembly.
Project paused due to health reasons of original engineer.