[Solved] USB-UART disappears after flashing micropython

[rowanalex]

I'm using an ESP8266 4MB lol1n board with a built-in ch340g usb-serial converter. In the bootloader mode, the tty device `/dev/tty.usbserial-141130` is detected by the mac os every time and the flash succeeds. After booting, the micropython wifi AP comes up. But, the tty.usbserial device does not appear in the list of devices under /dev anymore. How can I get access the serial device to appear. Same issue also happens with another board with the CP210x USB to UART Bridge, so dont think its a board issue. I've flashed a sonoff basic with micropython without any issues. How can I get stock micropython to enable the serial device so it shows up on my computer in normal (non-bootloader) mode?

[Roberthh]

On my ooold mac, the wemos lolin interface shows up as /dev/tty.SLAB_USBtoUART

[rowanalex]

Thanks for the reply @Roberthh.

After 2 days for triage, turned out the USB3 adaptor in use was the culprit. For some reason, in boot loader mode the usb-serial adaptor works fine but does not work when micropython starts up.

For others coming here in the future - some other fixes being suggested - making sure the cable supports data & disabling hardware flow control