does this work?

[ohsix]

$ cat /tmp/f.py

#!/usr/bin/env python3
from oatmeal import OatmealDevice
import logging

logging.basicConfig(format='%(asctime)s %(levelname)s: %(message)s',
                    level=logging.NOTSET)

class MyDevice(OatmealDevice):
    ROLE_STR = "MyDevice"

board = MyDevice.find()
print("Temperature: ", board.send_and_ack("TMPR").args[0])

cat f.ino

#define HARDWARE_ID_STR "MyDevice"
#include "oatmeal_protocol.h"

OatmealPort port = OatmealPort(&Serial, "MyDevice");

void setup() {
  port.init();
}

void loop() {
  OatmealMsg msg;
  while (port.check_for_msgs(&msg)) {
    if (msg.is_opcode("TMPR")) {
      port.start("TMP", 'A', port.next_token());
      port.append(32);
      port.append(48);
      port.finish();
    }
  }
}

this is on linux. initially I thought it was the timeout for ask_who, then I changed that directly and it still didn't work

in the udp monitor (with the changed timeout) there are messages going back and forth

<DISRdM>iS
<DISRdN>iV
<HRTRdAT>pb
<HRTRdBT>p?
<HRTRdCT>pd
<HRTRdDT>pA

<DISAdN"MyDevice",0,"\"UNDEF_ID\"","\"UNDEF_VER\"">$~

the log from running f.py

2021-01-10 22:01:51,371 DEBUG: Trying to connect to /dev/ttyUSB0...
2021-01-10 22:01:51,373 INFO: Starting reading/writing UART.
2021-01-10 22:01:51,374 DEBUG: Querying device...
2021-01-10 22:01:56,381 DEBUG: Missed ack: OatmealMsg('DISR', token='dM')
2021-01-10 22:01:56,393 INFO: Stopped reading/writing UART.
2021-01-10 22:01:56,393 INFO: Approximate UART received stats...
2021-01-10 22:01:56,393 INFO:   # frame too long: 0
2021-01-10 22:01:56,394 INFO:   # frame too short: 0
2021-01-10 22:01:56,394 INFO:   # missing start byte: 0
2021-01-10 22:01:56,394 INFO:   # missing end byte: 0
2021-01-10 22:01:56,394 INFO:   # non-ascii bytes: 0
2021-01-10 22:01:56,394 INFO:   # bad checksum: 0
2021-01-10 22:01:56,394 INFO:   # misc bad frames: 0
2021-01-10 22:01:56,394 INFO:   # good frames: 1
2021-01-10 22:01:56,401 INFO: Starting reading/writing UART.
2021-01-10 22:01:56,903 DEBUG: Missed ack: OatmealMsg('HRTR', True, token='dA')
2021-01-10 22:01:57,405 DEBUG: Missed ack: OatmealMsg('HRTR', True, token='dB')
2021-01-10 22:01:57,907 DEBUG: Missed ack: OatmealMsg('HRTR', True, token='dC')
2021-01-10 22:01:58,409 DEBUG: Missed ack: OatmealMsg('HRTR', True, token='dD')
Traceback (most recent call last):
  File "/tmp/f.py", line 11, in <module>
    board = MyDevice.find()
  File "/home/ohsix/.local/lib/python3.8/site-packages/oatmeal/device.py", line 204, in find
    role_device.toggle_heartbeats(True)
  File "/home/ohsix/.local/lib/python3.8/site-packages/oatmeal/device.py", line 159, in toggle_heartbeats
    self.port.send_and_ack(command, "HRTA")
  File "/home/ohsix/.local/lib/python3.8/site-packages/oatmeal/protocol.py", line 1427, in send_and_ack
    raise OatmealTimeout("No ACK! (%s retries, %s timeout)" % (
oatmeal.protocol.OatmealTimeout: No ACK! (3 retries, 0.5 timeout)