Micropython MAX5134

Simple object definition in python for controlling the MAX5134. A 4-channel 16-bit digital to analog converter. Tested with an ESP8266.

Contents:

• pyisotopomer
  • Features
  • Connections
  • Use

Features

• Write voltage to specified output pins (specify max voltage)
• Pre-load voltage output with LDAC
• Clear all DAC registers
• Software shutdown of the DAC
• Apply the DAC linearity function.

This module does not utilize the ALERT pin, nor does it have handling for daisy-chaining.

Connections

From Wemos D1 Mini ESP8266 → MAX5134

• D5 (GPIO14) → 10 (SCLK)
• D7 (GPIO13) → 8 (DIN)
• D8 (GPIO15) → 9 (CS)
• Ground → 7 & 15 (GND)
• 5V → 4 (DVDD)

It is highly recommended that you use a stable voltage regulator. The 5V rail typically drops to ~4V from USB power. If you insist on using the esp as the voltage reference, consider using the 3.3V rail:

• 5V → 2 (AVDD)
• 3.3V → 1 (REFI)

If using a REF02 → MAX5134

• G → 7 & 15 (GND)
• 6 (Vout) → 1 (REFI) Connect REF02 pin 2 (Vin) to a >9V source.

Connect MAX5134 pins 13 (M/Z) and 12 (LDAC) to GND or DVDD depending on your application.

Use

To initialize the object, define the CS and SPI pins, then attach it to the object. Below uses the pinout as described above for the wemos d1 mini with a 3.3V reference. It is not necessary to call the maximum voltage if you are using the ref02 as the default value is 5V:

from machine import Pin, SPI from MAX5134 import MAX5134 spi = SPI(1, baudrate=400000) cs = Pin(15, Pin.OUT) vmax = 3.3 dac = MAX5134(cs, spi, vmax)

Commanding an output voltage is used with write command. The first argument specifies the output pin to set, and the second is the desired voltage. The pin selection can be a single pin 0 thru 3, or a list if you wish to set multiple pins at once.

For a single pin:

dac.write(0, 2)  # Sets output pin 0 to 2 V

For all pins:

dac.write([0,1,2,3],1)  # Sets all pins to 1 V

To clear all dac registers:

dac.clear()

Placing a value on the LDAC register uses the same syntax as the write command. Unlike write, the value must later be pushed to the output:

dac.ldac(0, 2)  # Set the LDAC register to 2 V

Then load the LDAC register to the output of the specified pins:

dac.load(0) # Pushes LDAC register for pin 0 to the output

Software shutdown of a pin on the DAC:

dac.pwr(0)  # Turns off pin 0

Clear all registers and reset the DAC:

dac.clear()