The following files are daily firmware for ESP32-based boards without external SPIRAM.
This firmware is compiled using ESP-IDF v4.x. Some older releases are also provided that are compiled with ESP-IDF v3.x.
Program your board using the esptool.py program, found here.
If you are putting MicroPython on your board for the first time then you should first erase the entire flash using:
esptool.py --chip esp32 --port /dev/ttyUSB0 erase_flash
From then on program the firmware starting at address 0x1000:
esptool.py --chip esp32 --port /dev/ttyUSB0 --baud 460800 write_flash -z 0x1000 esp32-20190125-v1.10.bin