Using the MCP4822 DAC via SPI

This folder contains the source files for controlling MCP4822 dual channel 12-bit DAC via SPI bus, which is available e.g. on the Raspberry Pi minicomputer. The example is based on the REXLANG user-programmable function block of the REXYGEN.

It is controlled by an integer constants "CNI_CHx" (try changing it on-the-fly).

Timing of the project

The algorithm runs each 200 milliseconds (0.2 s). See the EXEC function block,
tick x ntick0 = 0.1 x 2 = 0.2

Prerequisites

• REXYGEN Runtime Core must be installed and running on the target device (Raspberry Pi).
• SPI bus must be enabled and available (e.g. /dev/spidev0.0 on the Raspberry Pi)
• The wiring must comply with the attached datasheet.

Running the example

• The *exec.mdl file is the project main file.
• Open it with REXYGEN Studio.
• Specify the SPI bus by the "p0" parameter of the REXLANG function block.
• Compile and download it to the target device.
• Switch to Watch mode and observe the algorithm.
• Enable online monitoring of the REXLANG block (Target->Watch Selection).

Documentation

• Press F1 for help on the selected function block in the REXYGEN Studio.
• Getting started with REXYGEN on the Raspberry Pi minicomputer
• Function blocks of REXYGEN
• MCP4921 datasheet (attached)
• REXYGEN Studio User Guide
• Complete documentation of REXYGEN

Additional information

• Raspberry Pi is a trademark of the Raspberry Pi Foundation.
• Visit the REXYGEN webpage for more information about the example projects and developing advanced automation and control solutions using REXYGEN.