AD5761_Micropython - AD5761 DAC Control on MicroPython

This project provides a full implementation for controlling the AD5761 Digital-to-Analog Converter on MicroPython. All testing is done on a Raspberry Pi Pico with RP2040. You might want to add timing interval between sync pulses and read/write operations if you encounter random bit in return values. Datasheet Reference: Datasheet

Features

• Control Register Operations: Set/Read the control register with the desired configuration.
• DAC register Operations: Write, update and read the DAC register using percentages of the full scale.
• Input Register Operations: Write and update to the input register without immediately updating the DAC, then update the DAC register from the input register.
• Daisy-Chain: Enable or disable daisy-chain functionality. Readback is disabled when daisy-chain is disabled.
• Reset: Perform a full reset or data reset to a power-up scale defined in the control register.

Requirements

• AD5761 DAC on a breakout board
• MicroPython on the Microcontroller
• Raspberry Pi Pico (or another supported microcontroller)

Getting Started

Hardware Setup

Connect the Raspberry Pi Pico to the AD5761 DAC using the following GPIO pins:

Pico Pin	AD5761 Pin
sclk_pin (e.g., GPIO 6)	SPI Clock (SCLK)
sdi_pin (e.g., GPIO 7)	SPI Data Input (SDI)
sdo_pin (e.g., GPIO 4)	SPI Data Output (SDO)
sync_pin (e.g., GPIO 5)	SPI Chip Select (SYNC)
alert_pin (e.g., GPIO 12)	Alert (optional, high when DAC is ready, low when DAC is not ready or in fault condition)

Usage

Below is an overview of its key methods:

Initialization

from AD5761 import AD5761

# Initialize Controller
ad5761 = AD5761(
    sclk_pin=6,       # SPI Clock Pin
    sdi_pin=7,        # SPI Data Input Pin
    sdo_pin=4,        # SPI Data Output Pin
    sync_pin=5,       # SPI Chip Select (SYNC) Pin
    alert_pin=12,     # Alert Pin (optional, needed for fault detection)
    debug=True        # Enable debugging
)

Full Reset

Perform a full software reset:

ad5761.reset()

Writing to Control Register

Write to the control register with the desired configuration:

# Write to control register with full scale, overrange disabled, straight binary, thermal shutdown enabled, zero scale power-up, 0V to 10V range
ad5761.write_control_register(
    cv=ad5761.CV_FULL_SCALE,
    ovr=ad5761.OVR_DISABLED,
    b2c=ad5761.B2C_BINARY,
    ets=ad5761.ETS_POWER_DOWN,
    pv=ad5761.PV_ZERO_SCALE,
    ra=ad5761.RA_10V_UNIPOLAR,
)

options are available in the Control Register Options section.

Writing to DAC Register

Write a percentage value to the DAC register and update the output:

# Write and update DAC with 50% of full scale
ad5761.write_update_dac_register(50)

Writing to Input Register

Write to the input register without updating the DAC (this also depend on the LDAC pin value, check the spec sheet for more information):

# Write 25% to the input register
ad5761.write_input_register(25)

Update DAC from Input Register

Update the DAC from the input register:

ad5761.update_dac_from_input_register()

Reading Registers

Read and print the DAC register value:

# Read DAC register and print its value
ad5761.read_dac_register()

Read and print the control register with detailed interpretation:

ad5761.read_control_register()

Daisy-Chain Control

Enable or disable daisy-chaining, readback is disabled when daisy-chain is disabled:

# Enable daisy-chain functionality
ad5761.set_daisy_chain(enabled=True)

# Disable daisy-chain functionality
ad5761.set_daisy_chain(enabled=False)

Software Data Reset

Perform a software data reset, resetting the DAC output to the power-up voltage set in the control register:

ad5761.software_data_reset()

Debug Mode

Pass debug=True during initialization for detailed debugging information:

Control Register Options

Below are configuration options for write_control_register function.

CV (Clear Voltage Selection)

• CV_ZERO_SCALE (0x0) - Clear to zero scale.
• CV_MIDSCALE (0x1) - Clear to midscale.
• CV_FULL_SCALE (0x2) - Clear to full scale.

OVR (Overrange Enable)

• OVR_DISABLED (0x0) - Overrange disabled.
• OVR_ENABLED (0x1) - Overrange enabled (up to 5% overrange).

B2C (Bipolar Range Coding)

• B2C_BINARY (0x0) - DAC input for bipolar output range is straight binary coded.
• B2C_TWOS_COMPLEMENT (0x1) - DAC input for bipolar output range is two's complement coded.

ETS (Thermal Shutdown Enable)

• ETS_NOT_POWER_DOWN (0x0) - The internal digital supply does not power down if die temperature exceeds 150°C.
• ETS_POWER_DOWN (0x1) - The internal digital supply powers down if die temperature exceeds 150°C.

PV (Power-Up Voltage)

• PV_ZERO_SCALE (0x0) - DAC powers up at zero scale.
• PV_MIDSCALE (0x1) - DAC powers up at midscale.
• PV_FULL_SCALE (0x2) - DAC powers up at full scale.

RA (Output Range Selection)

• RA_10V_BIPOLAR (0x0) - Output range: −10V to +10V.
• RA_10V_UNIPOLAR (0x1) - Output range: 0V to +10V.
• RA_5V_BIPOLAR (0x2) - Output range: −5V to +5V.
• RA_5V_UNIPOLAR (0x3) - Output range: 0V to +5V.
• RA_7_5V (0x4) - Output range: −2.5V to +7.5V.
• RA_3V (0x5) - Output range: −3V to +3V.
• RA_16V_UNIPOLAR (0x6) - Output range: 0V to +16V.
• RA_20V_UNIPOLAR (0x7) - Output range: 0V to +20V.

testing example

ad5761 = AD5761Controller(sclk_pin=6, sdi_pin=7, sdo_pin=4, sync_pin=5, alert_pin=12, debug=True)
# Perform a reset
ad5761.reset()
time.sleep(1)
# Configure DAC control register
ad5761.write_control_register(cv=ad5761.CV_FULL_SCALE, ra=ad5761.RA_10V_UNIPOLAR)
time.sleep(1)
# Write 50% value to DAC register
ad5761.write_update_dac_register(50)
time.sleep(1)
# Write 25% to input register without updating DAC
ad5761.write_input_register(25)
time.sleep(1)
# Update DAC from input register
ad5761.update_dac_from_input_register()
time.sleep(1)
# Perform a software data reset
ad5761.software_data_reset()

License

This project is licensed under the MIT License - see the LICENSE file for details.