Digilent Zybo

Overview

The Digilent Zybo (ZYnq BOard) is a feature-rich, ready-to-use embedded software and digital circuit development board. It is built around the Xilinx Zynq-7000 family, which is based on the Xilinx All Programmable System-on-Chip (AP SoC) architecture. This architecture tightly integrates a dual-core ARM Cortex-A9 processor with Xilinx 7-series Field Programmable Gate Array (FPGA) logic.

Hardware

Supported Features

The zybo board configuration supports the following hardware features:

Interface	Controller	Driver/Component
GICv1	on-chip	ARM generic interrupt controller v1
ARCH TIMER	on-chip	ARM architected timer
PINCTRL	on-chip	pinctrl
GPIO	on-chip	gpio
UART	on-chip	serial port-polling; serial port-interrupt

The default configuration can be found in the defconfig file: boards/arm/zybo/zybo_defconfig.

Other hardware features are not currently supported by the port.

Programming and Debugging

The Zynq-7000 series SoC needs to be initialized prior to running a Zephyr application. This can be achieved in a number of ways (e.g. using the Xilinx First Stage Boot Loader (FSBL), the Xilinx Vivado generated ps_init.tcl JTAG script, Das U-Boot Secondary Program Loader (SPL), …).

The instructions here use the U-Boot SPL. For further details and instructions for using Das U-Boot with Xilinx Zynq-7000 series SoCs, see the following documentation:

Building Das U-Boot

Clone and build Das U-Boot for the Digilent Zybo:

git clone -b v2022.04 https://source.denx.de/u-boot/u-boot.git
cd u-boot
make distclean
make xilinx_zynq_virt_defconfig
export PATH=/path/to/zephyr-sdk/arm-zephyr-eabi/bin/:$PATH
export CROSS_COMPILE=arm-zephyr-eabi-
export DEVICE_TREE="zynq-zybo"
make

Flashing

Here is an example for running the Hello World application via JTAG.

Ensure the board is configured for JTAG boot, open a serial terminal, turn on/reset the board (press the PS-SRST button), and initialize the Zynq-7000 series SoC by uploading and running the U-Boot SPL via JTAG.

Next, upload and run the Zephyr application:

# From the root of the zephyr repository
west build -b zybo samples/hello_world
west flash

You should see the following message in the terminal:

*** Booting Zephyr OS vx.xx.x-xxx-gxxxxxxxxxxxx ***
Hello World! zybo

Another option is to load and run the Hello World application via U-Boot. Copy u-boot/spl/boot.bin, u-boot/u-boot.img, and zephyr/zephyr.bin to a FAT32 formatted microSD card, insert the card in the SD MICRO slot on the Zybo board, ensure the board is configured for SD boot, and turn on the board.

Once U-boot is done initializing, load an run the Zephyr application:

Zynq> fatload mmc 0 0x0 zephyr.bin
817120 bytes read in 56 ms (13.9 MiB/s)
Zynq> go 0x0
## Starting application at 0x00000000 ...
*** Booting Zephyr OS vx.xx.x-xxx-gxxxxxxxxxxxx ***
Hello World! zybo

Debugging

Here is an example for the Hello World application.

Ensure the board is configured for JTAG boot, open a serial terminal, turn on/reset the board (press the PS-SRST button), and initialize the Zynq-7000 series SoC by uploading and running the U-Boot SPL via JTAG.

Next, upload and debug the Zephyr application:

# From the root of the zephyr repository
west build -b zybo samples/hello_world
west debug

Step through the application in your debugger, and you should see the following message in the terminal:

*** Booting Zephyr OS vx.x.x-xxx-gxxxxxxxxxxxx ***
Hello World! zybo