Update 10/07/2021: Given that Telink based CGG1's are readily avilable and the fact that there is no known way to install custom firmware on an NRF52 based CGG1 OTA, this effort has been abandonded and the repository archived. If you have a Telink based CGG1, see pvvx/ATC_MiThermometer for custom firmware and documentation.
The goal of this project is reverse engineer and ultimately develop a custom firmware for the Qingping CGG1 (also known as the ClearGrass CGG1 or Xiaomi CGG1) bluetooth temperature and humidity sensor.
Thanks to atc1441, as his work on the ATC_MiThermometer project inspired me to begin this effort.
See the project wiki for up to date documentation on the CGG1.