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Linux Userspace Examples

This repository provides linux application demos for common communication protocols: SPI, I2C, UART. The Vivado 2019.1 projects are posted on Vivado configurations for Linux Userspace examples repository (separate branch for each example). The Petalinux 2019.1 projects are posted on Petalinux project for Linux Userspace examples repository (separate branch for each example). The demos are provided as sources files. In order to use the demos, create in SDK a new linux application project and copy the provided demo sources into the new project sources folder, and then refresh the project sources. The demos are further described as used with Digilent Pmods specific to the demonstrated communication (PmodACL2 for SPI, PmodTMP3 for I2C, PmodUSBUART for UART). Still, if these Pmods are not available, the demos can be started and the protocols can be visualized over the specific communication lines.

SPI Demo

It is implemented using spidev linux spi driver. It demonstrates a simple SPI communication with PmodACL2. The demo configures the PmodACL2 device and repeatedly retrieves acceleration values for the three axis.

SPI Demo Vivado project

The demo is using AXI Quad SPI IP in the Vivado project, having its lines configured to the Pmod connector where PmodACL2 is plugged. The Vivado project for the SPI demo is posted here. It is configured for PmodACL2 plugged on JB Pmod connector.

SPI Demo Petalinux configuration

In order to use the spidev driver, the following node must exist in the device_user.dtsi:

&axi_quad_spi_0 {
	spidev@0 {
		reg = <0>;
		compatible = "spidev";
		spi-max-frequency = <25000000>;
	};
};

Petalinux project for the SPI demo is posted here.

I2C Demo

It is implemented using standard linux I2C driver. It demonstrates a simple I2C communication with PmodTMP3. The demo configures the PmodTMP3 device and repeatedly retrieves the ambient temperature.

I2C Demo Vivado project

The demo is using AXI IIC IP in the Vivado project, having its lines configured to the Pmod connector where PmodTMP3 is plugged. The Vivado project for the I2C demo is posted here. It is configured for PmodTMP3 plugged on JB Pmod connector.

I2C Demo Petalinux configuration

Petalinux project for the I2C demo is posted here.

UART Demo

It is implemented using standard linux TTY driver. It demonstrates a simple UART communication. It uses PmodUSB-UART to interface the UART lines with the PC.
The demo repeatedly echoes over UART data received over UART. Open a terminal and type some characters, they will be echoed back.

UART Demo Vivado project

Insert AXI UartLite IP in the Vivado project, configuring its lines to the Pmod connector where you connect PmodUSB-UART. The Vivado project for the UART demo is posted here. It is configured for PmodUSB-UART plugged on JB Pmod connector.

UART Demo Petalinux configuration

Petalinux project for the UART demo is posted here.