write bluetooth FiPy

[Tgasser]

Hello,
I don't understand why, but when I do char.write(), nothing happens... It print well 'ok' then I can wait nothing happens... Thanks if you have an idea !

from network import Bluetooth
import time
import ubinascii


bt = Bluetooth()
bt.start_scan(-1)

while True:
    adv = bt.get_adv()

    if adv:
        print(ubinascii.hexlify(adv.mac))
        if bt.resolve_adv_data(adv.data, Bluetooth.ADV_NAME_CMPL) == 'Blabla':
          try:
              conn = bt.connect(adv.mac)
              services = conn.services()
              for service in services:
                  time.sleep(0.050)
                  if service.uuid() == XXX
                      print('Reading chars from service = %x' % service.uuid())
                      chars = service.characteristics()
                      for char in chars:
                              if (char.uuid()==XXX):
                                  if(char.properties() & Bluetooth.PROP_WRITE):
                                      print('ok')
                                      char.write(b'0xa01f')
              conn.disconnect()
              break
          except:
              pass
    else:
        time.sleep(0.050)

[Tgasser]

@jcaron I read several articles to invert the bytes and read the right values. If I have val= b'\xdd\xee' tanks to struct.pack('<h', *struct.unpack('>h', val)) I get the inverse val= b'\xee\xdd'.

However, for val= b'\xxaa\xbb\xcc\xdd' I can't find a way to get val=b'\xdd\xcc\xbb\xaa'.

Do you have any idea how to help me? Thank you in advance!

[Tgasser]

@jcaron Thank you for your help, it works the way I wanted it to! Thanks for your advice.

[jcaron]

@Tgasser You have the code-quoting quotes the wrong way around, it's ```

I don't think you are sending what you think or want: you are sending the characters 0, x, a, 0, 1, f, not 0xa0 and 0x1f.

Instead of b'0xa01f', you can write b'\xa0\x1f' or bytes([0xa0,0x1f].

Note that the order may be reversed based on the required endianness.