STEVAL-HARVEST1 [STMicroelectronics]

The STEVAL-HARVEST1 energy harvesting expansion board is a shield to be used with NUCLEO-WL55JC1, based on STM32WL for LoRa connectivity, with a capability of measuring temperature through the STTS22H sensor, acceleration through the LIS2DU12 sensor, and temperature and relative humidity through the SHT40 sensor (from Sensirion). Moreover, It can detect the presence of stationary and moving human bodies through the STHS34PF80 sensor. The board is self-powered due to the energy harvested using the solar panel mounted on it. The storage capacitor is available for storing energy harvested from the solar panel.

The STEVAL-HARVEST1 expansion board is compatible with the Morpho connector pin assignment, and it can easily be plugged onto a STM32 NUCLEO-WL55 development board.

In this application, the STM32WL55 reads sensors and stores data in an internal memory. It manages energy by buffering it on a dedicated ceramic capacitor located at the bottom of the board, using solar power from both indoor and outdoor environments, without requiring an external PMIC. Additionally, it handles radio connectivity, specifically using the LoRaWAN protocol.

The board includes ceramic capacitors to store energy, which is used to run the application (sensor reading and LoRaWAN message transmission) during the day, as well as a SuperCAP to store energy for nighttime use.

• Energy harvesting board, based on a solar panel and sensors
• STTS22H, LIS2DU12, STHS34PF80, and SHT40 mounted on the board:
  • STTS22H sensor to measure temperature with accuracy ± 0.5°C
  • LIS2DU12 sensor to measure acceleration with selectable full scales of ±2 g, ±4 g, ±8 g, ±16 g
  • STHS34PF80 sensor to detect the presence and motion of an object
  • SHT40 sensor to measure relative humidity and temperature from Sensiron
• The board, connected to NUCLEO-WL55JC1, can send the LoRa packet using only energy harvested from a solar panel mounted on the board. It is a battery free solution
• Besides running the user application, the STM32WL manages energy through a ceramic capacitor charged by solar power, without requiring an external PMIC, while also handling radio connectivity
• The packet consists of data from sensors (STTS22H, LIS2DU12, STHS34PF80, SHT40) mounted on the STEVAL-HARVEST1
• Compatible with STM32 NUCLEO-WL55 board
• Equipped with Morpho connector
• RoHS compliant