ads1x1x: added support for ADC chip (#6584)

Added a temperature sensor configuration for ADS1103, ADS1104, ADS1105, ADS1113, ADS1114 and ADS1115 chips that can be used to add Analog to Digital Conversion capability to machines that don't have that on their own. Like Raspberry Pi's or if more analog input pins are needed than the chip provides like for RP2040. Generally they can be used for any analog input, but the typical use case is for temperature measurement. This code also has been written with temperature measurement in mind and not as a general ADC.

Signed-off-by: Konstantin Koch <korsarnek@gmail.com>
Signed-off-by: Jack Wakefield <jackwakefield@protonmail.com>

docs/Config_Reference.md

@@ -4936,6 +4936,50 @@ vssa_pin:
 #   noise. The default is 2 seconds.
 ```
 
+### [ads1x1x]
+
+ADS1013, ADS1014, ADS1015, ADS1113, ADS1114 and ADS1115 are I2C based Analog to
+Digital Converters that can be used for temperature sensors. They provide 4
+analog input pins either as single line or as differential input.
+
+Note: Use caution if using this sensor to control heaters. The heater min_temp
+and max_temp are only verified in the host and only if the host is running and
+operating normally. (ADC inputs directly connected to the micro-controller
+verify min_temp and max_temp within the micro-controller and do not require a
+working connection to the host.)
+
+```
+[ads1x1x my_ads1x1x]
+chip: ADS1115
+#pga: 4.096V
+#   Default value is 4.096V. The maximum voltage range used for the input. This
+#   scales all values read from the ADC. Options are: 6.144V, 4.096V, 2.048V,
+#   1.024V, 0.512V, 0.256V
+#adc_voltage: 3.3
+#   The suppy voltage for the device. This allows additional software scaling
+#   for all values read from the ADC.
+i2c_mcu: host
+i2c_bus: i2c.1
+#address_pin: GND
+#   Default value is GND.  There can be up to four addressed devices depending
+#   upon wiring of the device. Check the datasheet for details. The i2c_address
+#   can be specified directly instead of using the address_pin.
+```
+
+The chip provides pins that can be used on other sensors.
+
+```
+sensor_type: ...
+#   Can be any thermistor or adc_temperature.
+sensor_pin: my_ads1x1x:AIN0
+#   A combination of the name of the ads1x1x chip and the pin. Possible
+#   pin values are AIN0, AIN1, AIN2 and AIN3 for single ended lines and
+#   DIFF01, DIFF03, DIFF13 and DIFF23 for differential between their
+#   correspoding lines. For example
+#   DIFF03 measures the differential between line 0 and 3. Only specific
+#   combinations for the differentials are allowed.
+```
+
 ### [replicape]
 
 Replicape support - see the [beaglebone guide](Beaglebone.md) and the