Ultra-Low-Power STM32WL LoRa Device
Budget: ₹12,500 – ₹37,500 INR
I am building a battery-powered edge node around the STM32WL (LoRa-E5 module) that must sit in the field for years on a single 5 000 mAh cell. To reach that target I need both the hardware design and the accompanying firmware created with an obsessive focus on nano-amp sleep currents and efficient duty-cycling.
Core capabilities
• Data logging to internal flash or external EEPROM so records are retained between wake-ups.
• LoRa communication only; no Bluetooth or Wi-Fi. The node will periodically wake, send an uplink, accept a downlink if present, and return to deep sleep.
• Simple sensor block: one digital interrupt input (e.g., reed switch/pulse counter) plus one digital output that can drive an external load for a short, timed burst.
Hardware scope
– Complete schematic and BOM for the STM32WL-based board, including optimal power path, reverse-polarity and ESD protection, and a proven antenna layout for 868/915 MHz.
– PCB layout (Altium, KiCad, or similar) ready for fabrication.
– Design documents that justify each component choice in terms of quiescent current and RF performance.
Firmware scope
– Bare-metal or STM32CubeIDE project written in C.
– Tickless low-power framework leveraging STOP/SHUTDOWN modes, RTC wake-ups, and interrupt-driven I/O.
– LoRaWAN Class A stack configured for EU868 / US915 with ADR support.
– Non-volatile ring buffer for data records with configurable sample and transmit intervals.
– Unit-tested drivers for digital input debouncing and the high-side power switch on the output line.
Acceptance criteria
1. Average current in sleep ≤ 2 µA (measured on my bench with battery simulator).
2. End-to-end packet successfully delivered through a public LoRaWAN gateway with RSSI/SNR logged.
3. 10 000 wake-up / log / transmit cycles without firmware crash or data loss.
4. Complete build instructions and reproducible firmware image from a clean checkout.
If this challenge matches your low-power-IoT skill set, let’s talk details so we can get the first prototypes spinning quickly.
Core capabilities
• Data logging to internal flash or external EEPROM so records are retained between wake-ups.
• LoRa communication only; no Bluetooth or Wi-Fi. The node will periodically wake, send an uplink, accept a downlink if present, and return to deep sleep.
• Simple sensor block: one digital interrupt input (e.g., reed switch/pulse counter) plus one digital output that can drive an external load for a short, timed burst.
Hardware scope
– Complete schematic and BOM for the STM32WL-based board, including optimal power path, reverse-polarity and ESD protection, and a proven antenna layout for 868/915 MHz.
– PCB layout (Altium, KiCad, or similar) ready for fabrication.
– Design documents that justify each component choice in terms of quiescent current and RF performance.
Firmware scope
– Bare-metal or STM32CubeIDE project written in C.
– Tickless low-power framework leveraging STOP/SHUTDOWN modes, RTC wake-ups, and interrupt-driven I/O.
– LoRaWAN Class A stack configured for EU868 / US915 with ADR support.
– Non-volatile ring buffer for data records with configurable sample and transmit intervals.
– Unit-tested drivers for digital input debouncing and the high-side power switch on the output line.
Acceptance criteria
1. Average current in sleep ≤ 2 µA (measured on my bench with battery simulator).
2. End-to-end packet successfully delivered through a public LoRaWAN gateway with RSSI/SNR logged.
3. 10 000 wake-up / log / transmit cycles without firmware crash or data loss.
4. Complete build instructions and reproducible firmware image from a clean checkout.
If this challenge matches your low-power-IoT skill set, let’s talk details so we can get the first prototypes spinning quickly.
Related categories:
C Programming
Electronics
Microcontroller
PCB Layout
Arduino
Embedded Systems
LoRa
STM32