bleio: cccd not properly set after Peripheral was added to a Service?

[edwios]

Hi,

I have the following piece of code, however when I run it, it returned CCCD error:
OSError: Failed to read CCCD value, err 0x3002

	chara = bleio.Characteristic(uuid_char_temp, notify=True, read=True, write=False)
	serv = bleio.Service(uuid_env_sense, [chara])
	periph = bleio.Peripheral([serv], name="BME680")

	periph.start_advertising()

	while True:
		send_temp()
		time.sleep(5)

send_temp() is essentially chara.value = bytearray([temp & 0xFF, temp >> 8])

Did I missed anything?

Note: Circuitpython master tree on Feb 8th, nRF52840 dongle

Regards,
Ed

[edwios]

Found what's wrong, it was due to a bug causing send_temp() to set the chara.value before periph.connected returned True.

Closing the issue.

BTW, great works on the bleio, it is really friendly and very easy to use!

[dhalbert]

One question is whether it should be safe to set the value when not connected. Maybe it should just suppress trying to notify in that case, since you may want to set an initial value.

Thanks for the compliment! Getting to a pleasant API is hard.

[edwios]

For a peripheral, I don't know what is the point of writing to a characteristic when it is not connected.

[dhalbert]

You might want to initialize the characteristic with a value before you start advertising. When a client connects, they might request the value immediately.

[tcpipchip]

right!