Accessing radio temperature causes lib code to hang.

[RobCranfill]

Hardware/CP: Adafruit CircuitPython 9.2.9 on 2025-09-07; Adafruit Feather RP2040 RFM with rp2040

Accessing the property .temperature the second time causes the code to hang - not return, no error - as demonstrated in the attached code.

test_rfm69_temp.py

If you change line 32, FORCE_IDLE = False to True, it works, otherwise it fails.

This happens whether the receiver gets a packet or not.

BTW, the code documentation does mention that accessing .temperature interferes with receiving/sending, but this just goes out to lunch.

@property
def temperature(self) -> float:
    """The internal temperature of the chip in degrees Celsius. Be warned this is not
    calibrated or very accurate.

    .. warning:: Reading this will STOP any receiving/sending that might be happening!
    """

This was discussed a bit at https://forums.adafruit.com/viewtopic.php?t=220388

Example output (sorry for the formatting glitches)

Successful run (FORCE_IDLE = True)

`
Adafruit CircuitPython 9.2.9 on 2025-09-07; Adafruit Feather RP2040 RFM with rp2040

soft reboot

Auto-reload is off.
code.py output:

RFM69 status:

radio.bitrate=250000.0
radio.frequency_deviation=250000.0
radio.rssi=-127.5
radio.temperature=30.0

Listening...
Got packet=None
RFM69 status:

radio.bitrate=250000.0
radio.frequency_deviation=250000.0
radio.rssi=-84.0
radio.temperature=31.0

Listening...
Got packet=None
RFM69 status:

radio.bitrate=250000.0
radio.frequency_deviation=250000.0
radio.rssi=-83.0
radio.temperature=31.0

Listening...
Traceback (most recent call last):
File "code.py", line 17, in
File "test_rfm69_temp.py", line 43, in
File "adafruit_rfm69.py", line 863, in receive
File "adafruit_rfm69.py", line 163, in check_timeout
File "adafruit_rfm69.py", line 731, in payload_ready
File "adafruit_rfm69.py", line 401, in _read_u8
File "adafruit_rfm69.py", line 391, in _read_into
KeyboardInterrupt:

Code done running.
`

Failed run (FORCE_IDLE = False)

`
RFM69 status:

radio.bitrate=250000.0
radio.frequency_deviation=250000.0
radio.rssi=-127.5
radio.temperature=30.0

Listening...
Got packet=None
RFM69 status:

radio.bitrate=250000.0
radio.frequency_deviation=250000.0
radio.rssi=-86.5

Traceback (most recent call last):
File "code.py", line 17, in
File "test_rfm69_temp.py", line 39, in
File "test_rfm69_temp.py", line 25, in show_radio_status
File "adafruit_rfm69.py", line 486, in temperature
File "adafruit_rfm69.py", line 244, in get
File "adafruit_rfm69.py", line 401, in _read_u8
File "adafruit_rfm69.py", line 391, in _read_into
KeyboardInterrupt:

Code done running.
`

That's all we get until ctrl-C is pressed.

[jerryneedell]

I have reproduced this and will try to implement a workaround.
BTW -- using listen() instead if idle() does not work.

I'll just try setting the radio to idle after the temperature has been read.

[jerryneedell]

ahhh -- setting the radio to idle AFTER the temperature read did not work, it must be set to idle BEFORE the temperature reading is attempted.

There really should also be a timeout and error raised if the read fails rather than hanging. Unfortunately, this will add even more code to the very constrained adafruit_rfm69 library so it may not be worth adding the timeout.
My change so far is just to add the call to seff.idle() at the start:

@property
    def temperature(self) -> float:
        """The internal temperature of the chip in degrees Celsius. Be warned this is not
        calibrated or very accurate.

        .. warning:: Reading this will STOP any receiving/sending that might be happening!
        """
        self.idle() # set radio to idle before reading temperature.
        # Start a measurement then poll the measurement finished bit.
        self.temp_start = 1
        while self.temp_running > 0:
            pass
        # Grab the temperature value and convert it to Celsius.
        # This uses the same observed value formula from the Radiohead library.
        temp = self._read_u8(_REG_TEMP2)
        return 166.0 - temp

this appears to resolve the issue, but I don't like leaving the while self.temp_running >0: loop with the potential to hang. It appears that that is what has been happening to cause this issue.
As noted , to avoid adding extra code, I guess we can just live with this.

I'll do a bit more testing then submit a PR for review.