Download ESP8266_4mb_combined_4096.bin firmware at http://www.espruino.com/Download. Make sure to get 4MB combined version - ending with esp8266_4mb_combined_4096.bin.
git clone esptool from: https://github.com/espressif/esptool.git
To run the esptool on MAC:
pip3.7 install --user -e .
python3.7 ./esptool.py --port /dev/tty.usbserial-14240 --baud 115200 write_flash --flash_freq 80m --flash_mode qio --flash_size 4MB-c1 0x0000 ~/code/GITRep/POCs/Espruino/espruino_2v06_esp8266_4mb_combined_4096.bin
Test sketch:
var on = false;
setInterval(function() {
on = !on;
D2.write(on);
}, 500);