Add support for the ADS131M02 and ADS131M04 ADC sensors

* Support for configuring one or more channels to be summed.
* Configure the sample rate and gain
* Enable high perfomrance mode by default
* Check for unexpected device resets and CRC data errors while sampling

Signed-off-by: Gareth Farrington <gareth@waves.ky>

Author: garethky

docs/Config_Reference.md

@@ -5963,6 +5963,70 @@ data_ready_pin:
 #   and 'analog_supply'. Default is 'internal'.
 ```
 
+#### ADS131M02
+The ADS131M02 is a 24 bit, 2-channel delta-sigma ADC with simultaneous
+sampling. It uses SPI communication and provides high precision measurements
+suitable for load cell probing.
+```
+[load_cell]
+sensor_type: ads131m02
+cs_pin:
+#   The pin connected to the ADS131M02 chip select line. This parameter must
+#   be provided.
+#spi_speed: 8192000
+#   SPI bus speed. The default is 8.192 MHz.
+#spi_bus:
+#spi_software_sclk_pin:
+#spi_software_mosi_pin:
+#spi_software_miso_pin:
+#   See the "common SPI settings" section for a description of the
+#   above parameters.
+data_ready_pin:
+#   Pin connected to the ADS131M02 data ready (DRDY) line. This parameter must
+#   be provided.
+#channels: 0
+#   Comma separated channel list of channels to enable and sum. Valid channels are 0 and 1.
+#   The default is 0.
+#gain: 128
+#   Programmable gain amplifier setting. Valid values are 1, 2, 4, 8, 16, 32,
+#   64, and 128. The default is 128.
+#sample_rate: 500
+#   Sample rate in samples per second. Valid values are 250, 500, 1000, 2000,
+#   4000, 8000, 16000, and 32000. The default is 500.
+```
+
+#### ADS131M04
+The ADS131M04 is a 24 bit, 4-channel delta-sigma ADC with simultaneous
+sampling. It uses SPI communication and provides high precision measurements
+suitable for load cell probing. Up to 4 channels can be combined into a single
+sensor ideal for under bed load cells.
+```
+[load_cell]
+sensor_type: ads131m04
+cs_pin:
+#   The pin connected to the ADS131M04 chip select line. This parameter must
+#   be provided.
+#spi_speed: 8192000
+#   SPI bus speed. The default is 8.192 MHz.
+#spi_bus:
+#spi_software_sclk_pin:
+#spi_software_mosi_pin:
+#spi_software_miso_pin:
+#   See the "common SPI settings" section for a description of the
+#   above parameters.
+data_ready_pin:
+#   Pin connected to the ADS131M04 data ready (DRDY) line. This parameter must
+#   be provided.
+#channels: 0
+#   Comma separated channel list to enable and sum. Valid channels are: 0, 1, 2, 3. The default is channel 0.
+#gain: 128
+#   Programmable gain amplifier setting. Valid values are 1, 2, 4, 8, 16, 32,
+#   64, and 128. The same gain is applied to all channels.
+#sample_rate: 500
+#   Sample rate in samples per second. Valid values are 250, 500, 1000, 2000,
+#   4000, 8000, 16000, 32000. The default is 500.
+```
+
 ### [load_cell_probe]
 Load Cell Probe. This combines the functionality of a [probe] and a [load_cell].
 

docs/Load_Cell.md

@@ -25,6 +25,8 @@ reference_tare_counts: 12345
   * [`hx711`](Config_Reference.md#hx711)
   * [`hx717`](Config_Reference.md#hx717)
   * [`ads1220`](Config_Reference.md#ads1220)
+  * [`ads131m02`](Config_Reference.md#ads131m02)
+  * [`ads131m04`](Config_Reference.md#ads131m04)
 
 - `counts_per_gram: 245`\
   _Default Value: None_\
@@ -332,7 +334,7 @@ Recommended sensor characteristics:
 - Programmable gain amplifier with 128× gain to eliminate external amplifiers
 - SPI reset indication to detect sensor restarts, a common indication of electrical problems
 - Selectable sample rate between 350 Hz and 2 kHz (rates below 250 Hz require slower probing speeds and increase toolhead force)
-- For under-bed applications with multiple load cells, simultaneous sampling on all channels (multiplexed ADCs have settling delays after channel switches)
+- For under-bed applications with multiple load cells, use an ADC with simultaneous sampling on all channels, such as the [ADS131M04](Config_Reference.md#ads131m04). Multiplexed ADCs have settling delays after channel switches and issues with time smearing of the readings which reduce accuracy.
 
 Klipper's `bulk_sensor` and `load_cell_probe` infrastructure simplifies support for new sensors. Sensors can be configured from Python. with a minimal sampling loop written in C.
 

klippy/extras/bus.py

@@ -129,6 +129,11 @@ def spi_send(self, data, minclock=0, reqclock=0):
             [self.oid, data], minclock=minclock, reqclock=reqclock
         )
 
+    def spi_send_wait_ack(self, data, minclock=0, reqclock=0):
+        self.spi_send_cmd.send_wait_ack(
+            [self.oid, data], minclock=minclock, reqclock=reqclock
+        )
+
     def spi_transfer(self, data, minclock=0, reqclock=0):
         return self.spi_transfer_cmd.send(
             [self.oid, data], minclock=minclock, reqclock=reqclock

klippy/extras/load_cell/__init__.py

@@ -6,13 +6,17 @@
 from klippy.configfile import ConfigWrapper
 from klippy.printer import Printer, SubsystemComponentCollection
 
-from . import ads1220, hx71x
+from . import ads131m0x, ads1220, hx71x
 from .load_cell import LoadCell
 
 
 # register sensors that implement BulkAdcSensor
 def register_components(subsystem: SubsystemComponentCollection):
-    sensors = hx71x.HX71X_SENSOR_TYPES | ads1220.ADS1220_SENSOR_TYPE
+    sensors = (
+        hx71x.HX71X_SENSOR_TYPES
+        | ads1220.ADS1220_SENSOR_TYPE
+        | ads131m0x.ADS131M0X_SENSOR_TYPES
+    )
     for name, sensor in sensors.items():
         subsystem.register_component("load_cell_sensors", name, sensor)