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https://github.com/robert-hh/CS1237

MicroPython driver for the CS1237 ADC
https://github.com/robert-hh/CS1237

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MicroPython driver for the CS1237 ADC

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README 

        
# CS1237: MicroPython class for the CS1237 ADC



This is a short and simple class for the CS1237 ADC. It supports reading

the ADC value, reading the temperature and configuring the various device

modes.



Tested with MicroPython ports for RP2040, STM32, SAMD, i.MX RT (e.g. Teensy),

ESP32, ESP8266, NRF52840 and W600. Approximate times for reading an ADC value:



- RP2040 at 125 MHz: 450 µs  

- PYBD SF6 at 192 MHz: 250 µs  

- Teensy 4.1 at 600 MHz: 100 µs  

- SAMD51 at 120 MHz: 450 µs   

- SAMD21 at 48 MHz: 1.2 ms   

- ESP32 at 160 MHz: 900 µs  

- ESP8266 at 80 MHz: 1.2 ms  

- NRF52840: 800µs.  

- Renesas RA6M2 at 120 MHz: 600µs

- W600 at 80 MHz: 900 µs  



The nrf port has the problem that the device cannot be configured when using the IRQ based driver.

NRF52840 based devices have worked in the test

using the polling driver. Otherwise the CS1237 operates at it's default

mode, which is gain=128, rate=10, channel=0.

pin.irq() seems not to work at the Renesas port, at least not with the tested EV-RA6M2 board.

It can be configured, but refuses to work. The polling driver works.



## Constructor



### cs1237 = CS1237(clock_pin, data_pin[, gain=1, rate=10, channel=0])



This is the GPIO constructor. data_pin and clock_pin are the pin objects

of the GPIO pins used for the communication. The arguments for gain, rate and channel

are optional and can later be re-configured using the init() method.



## Methods



### cs1237.init(gain=None, rate=None, channel=None)



Configures or re-configures the ADC. All arguments are optional.

Accepted values for **gain** are 1, 2, 64, 128 and for

**rate** are 10, 40, 640, 1280.

Channel values are:



- 0 : ADC reading

- 1 : Chip retention (sleep?)

- 2 : Temperature reading

- 3 : Internal short of the input



At data rates of 640 and 1280 reading with a slow MCU may return wrong

values, and configuring the device may fail. Then only a power cycle

will reset the device. Since the current consumption of the CS1237 is

low, it can be supplied by a GPIO output, making power cycling easy.  



According to the test, Teensy 4.x and PYBD SF6 work fine at a rate

of 1280. The RP2040, SAMD51 and Renesas RA6M2 work fine at a rate at 640

and can still be configured back.  

ESP32, ESP8266, nrf52, SAMD21 and W600 can be configured once for a rate

of 640, but cannot reset back to a lower rate and do not support

temperature reading when set to the 640 rate.



### result = cs1237.read()

### result = cs1237()



Returns the actual reading of the ADC or temperature.



### cs1237.get_config()



Returns the tuple of (gain, rate, channel) as read back from the ADC.



### cs1237.config_status()



Returns True if a new configuration has been properly updated.



### cs1237.calibrate_temperature(temp [, reference_value])



Set the calibration values for the temperature sensor. temp is the actual

°C value. If both the temperature and a reference value are supplied,

it is taken as the calibration tuple of the sensor. If not, the

reference value is read from the sensor.

The reference value can be obtained by configuring the sensor for temperature

reading and calling cs1237.read().



### cs1237.temperature(temp)



Return the actual temperature reading. The reference point has to be

configured before using calibrate_temperature().



### cs1237.power_down()



Set the CS1237 device to sleep mode.



### cs1237.power_up()



Switch the CS1237 on again.



More methods exists but are used only internally by the CS1237 class.



## Examples



```

# Connections:

# Pin # | CS1237

# ------|-----------

# 12    | data_pin

# 13    | clock_pin

#



from cs1237 import CS1237

from machine import Pin



data = Pin(12)

clock = Pin(13)



# Create a CS1237 instance with default values for gain, rate and channel

cs1237 = CS1237(clock, data)



# get ADC readings

value = cs1237.read()

# Alternative for reading the value

value = cs1237()



# change the gain

cs1237.init(gain=2)

value = cs1237.read()



# return the ADC settings

gain, rate, channel = cs1237.get_config()



# Alternative for showing the properties

print(cs1237)



# Calibrate the temperature reading

cs1237.calibrate_temperature(22.1)



# get the temperature

temp_celsius = cs1237.temperature()



# Calibrate the temperature reading using a known set point

# which has to be determined only once for a device.

cs1237.calibrate_temperature(20.0, 769000)



```



## Files



- **cs1237.py** CS1237 driver using Interrupts.

- **cs1237_poll.py** CS1237 driver use polling to detect the sync pulse. The

driver may fail on slow devices like ESP8266, SAMD21 or W600.

- **README.md**  Documentation file.