The PSF-A85 module adopts ESP8285 chip, so the firmware we update is ESP8285 firmware. And the firmware update process is the same as ESP8266's.
Firstly, build up a minimal system for PSF-A85 module. Then set GPIO0 in low level, press RESET.
Open the ESP FLASH DOWNLOAD TOOL. Connect serial port, select the corresponding com port. Select your bin file to “Dwonload Path Config”.
Then set SPI FLASH CONFIG exactly the same as below picture.
If your firmware size is 1MB, then remember to upload as bellows:
Finally, click START to proceed programming.
After programming completed, press RESET, and set GPIO0 in high level.