0503-04 LTC2422 ADC
Example Projects > 0503 Generic SPI Communication > 0503-04 LTC2422 ADC
Reading LTC2422 ADC data via SPI bus
This folder contains the source files for reading ADC data from the LTC2422 2-channel 20-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 REXYGEN.
See the source *.c file for details on reading the data via the SPI bus.
The data obtained from the ADC chip are displayed in raw form and also converted to voltage readings using the LIN function block. The y2 parameter of the LIN function blocks must be changed according to the supplied voltage reference (3.3V reference is assumed by default).
The measured data is recorded in the TRND block which allows displaying of the trends (graphs) in the Watch mode of REXYGEN Studio or in the REXYGEN Diagnostics diagnostic tool.
Timing of the project
The algorithm runs each 500 milliseconds (0.5 s). See the EXEC function block,
tick x ntick0 = 0.05 x 10 = 0.5
- 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).
- Apply external voltage to the ADC pins and observe the received data.
- 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
- LTC2422 datasheet (attached)
- REXYGEN Studio User Guide
- Complete documentation of REXYGEN