Swallow i2c read timeouts

src/klipper_sgp40/__init__.py

@@ -8,8 +8,10 @@
 import logging
 import math
 import re
+from logging import ERROR, WARNING
 from struct import unpack_from
 
+from ...serialhdl import error  # type:ignore
 from .. import bus  # type:ignore
 from .gia import GasIndexAlgorithm
 
@@ -83,7 +85,6 @@ def __init__(self, config):
         self.raw = self.voc = self.temp = self.humidity = 0
         self.min_temp = self.max_temp = 0
         self.step_timer = None
-        self._measuring = False
 
         mean = config.getfloat("voc_mean", None)
         stddev = config.getfloat("voc_stddev", None)
@@ -213,7 +214,7 @@ def _init_sgp40(self):
         self._wait_ms(500)
         response = self._read()
         if response[0] != 0xD400:
-            logging.error(self._log_message("Self test error"))
+            self._log(ERROR, "Self test error")
 
         self.step_timer = self.reactor.register_timer(self._handle_step)
 
@@ -228,12 +229,6 @@ def _handle_step(self, eventtime):
             self._is_hot(h, eventtime) for h in self._heaters
         )
 
-        if self._measuring:
-            # Calculate VOC index
-            response = self._read()
-            self.raw = response[0]
-            self.voc = self._gia.process(self.raw)
-
         # Get reference temperature
         if self.temp_sensor:
             self.temp = self.printer.lookup_object(
@@ -256,14 +251,26 @@ def _handle_step(self, eventtime):
         else:
             self.humidity = humidity
 
-        # Start next measurement
+        # Read sample
         cmd = (
             MEASURE_RAW_CMD_PREFIX
             + _humidity_to_ticks(self.humidity)
             + _temperature_to_ticks(self.temp)
         )
         self.i2c.i2c_write(cmd)
-        self._measuring = True
+        self._wait_ms(50)
+        try:
+            response = self._read()
+        except error as exc:
+            if hasattr(exc, "message") and "i2c_read_response" in exc.message:
+                self._log(WARNING, "Read timeout")
+                self.raw = 0
+                self.voc = 0
+            else:
+                raise exc
+        else:
+            self.raw = response[0]
+            self.voc = self._gia.process(self.raw)
 
         # Schedule next step
         measured_time = self.reactor.monotonic()
@@ -286,13 +293,13 @@ def _read(self, len=1):
             if not _check_crc8(
                 response[i : i + SGP40_WORD_LEN], response[i + SGP40_WORD_LEN]
             ):
-                logging.warning(self._log_message("Checksum error on read!"))
+                self._log(WARNING, "Checksum error on read!")
             data.append(unpack_from(">H", response[i : i + SGP40_WORD_LEN])[0])
 
         return data
 
-    def _log_message(self, message):
-        return "SGP40 %s: %s" % (self.name, message)
+    def _log(self, level, msg):
+        logging.log(level, "SGP40 %s: %s" % (self.name, msg))
 
     def get_status(self, eventtime):
         return {