USB HID mode

Hi I just test HID and it’s working. The problem is with your script, you’re sending bytes in the wrong order. This script works:

import pyb, time

kb = pyb.USB_HID()
buf = bytearray(8)

while(True):# Sending T
    # key down
    buf[0] = 0x02 # LEFT_SHIFT
    buf[2] = 0x17 # keycode for 't/T'
    kb.send(buf)
    time.sleep(10)
    # key up
    buf[0] = 0x00
    buf[2] = 0x00
    kb.send(buf)
    time.sleep(1000)

Please read MicroPython’s tutorial first to understand how HID works: