ExpertAnalog and Test Equipment
Four-Channel MCP4728 DAC Signal Source
Generate four adjustable low-voltage analog outputs and learn DAC resolution, reference voltage, and output buffering.
Parts from the database
- MCP4728-E/UN × 1Four-channel 12-bit DAC; use on a breakout
- Raspberry-Pi-Pico × 1I²C controller
- OPA197IDR × 1Optional buffer on a correctly designed board
Other supplies
- MCP4728 breakout with reference/power documentedCommon build supply
- PicoCommon build supply
- multimeterCommon build supply
- optional op-amp buffer boardCommon build supply
- jumper wiresCommon build supply
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Connections
- Connect breakout logic supply and ground as documented; SDA to GP4, SCL to GP5.
- Connect each DAC output to a high-impedance meter input first; do not connect directly to a speaker, motor, or unknown circuit.
- Use a common analog ground for the DAC and measurement instrument.
Build steps
- Install a library for MCP4728 and verify I²C communication.
- Write midscale to one channel and measure its output; then test zero and near-full-scale codes.
- Update all four channels with distinct setpoints and verify channel mapping.
- Only after basic measurements pass, add a buffer and explore a slow stepped waveform.
Software and firmware setup
Firmware is required, but a complete four-channel waveform sketch is not included yet. Install an MCP4728 library compatible with the Pico Arduino core and run its basic I2C/write example. Confirm each channel with a high-impedance meter before connecting any external circuit; the DAC cannot drive a load directly.
Test your build
Each channel should produce a stable voltage proportional to its 12-bit code and the DAC reference/supply. Exact full-scale behavior depends on the breakout configuration and load.
Troubleshooting
- If no device is found, check address straps and bus pull-ups.
- If measured voltages are scaled unexpectedly, inspect reference selection and supply voltage.
- If outputs sag, the load is too heavy; use a buffer designed for the output range.
Safety and limitations
Keep outputs within the DAC and receiving circuit voltage limits. This is a low-voltage signal source, not a power supply or function generator for mains equipment.
Manufacturer and platform documentation
Community Notes for This Project
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