First SoC-App in Vitis / Setup with ZYBO and integrating HW-Design

[DrF16]

Hey guys,

I have multiple beginner questions for Vitis with ZYBO (7010).

I have a simple project writing to RAM via DMA with AXI on my ZYBO. ( XADC - tlastgen - DMA -> PS ).

I finished the pipeline in Vivado and exported the HW as xsa and started a platform in Vitis and now want to begin an Application project in order to test the functionality.

I want to stream/visualize ADC values in the terminal on my host PC and see it by UART. I am unsure what is required to develop the hello-world example into this kind of application and how to work with the board. Below I have topically sorted all of my current challenges and enumerated them. I hope it is easy to gain an insight into the ideas. I would gladly supply logs or further information if required.

Board-related questions:

1. Right now I have no SD card and have the micro-usb (UART/PROG) as a power-source, hardware configuration, UART connection and I want to flash the standalone hello-world example form Vitis to the board. Is this the way to go? Can I directly write the FSBL files /application project to on-chip flash or do I need an SD Card? (1.1) How do I do it? (1.2) Is this all even possible with just one micro-usb? (1.3)

2. In hardware (ZYNQ PS block) I turned on UART 1 in MIO. Does this need to be turned on? (2.1) Because when I connect the board (I use Ubuntu on the host) and turn it on both /dev/ttyUSB0 and /dev/ttyUSB1 appear, even though I only turned on UART1. After doing "sudo picocom -b 115200 /dev/ttyUSB1" it looks fine, but Vitis is throwing an error when I want to create a shell on /dev/ttyUSB1. (permission denied) (2.2)

DMA and software related questions:

3. As I understand, my DMA (no CDMA/VDMA) starts writing to the specified RAM address that I can see in Vivado. Since this is my first working example, I have an ADC with a high sample rate just forwarding to the DMA in a high rate and I have 512MB of RAM for the DMA. Will it just deposit 16bit blocks one-by-one until it is full? (3.1) How do I reset it to start again on the first address? (3.2)

4. My plan was to take the Hello-World example and just read the contents of the RAM locations in 16bit/2byte blocks and convert them (char * data = 0x0000000;), maybe visualize so I can see if the output of the DMA-ADC toolchain is correct. Will I need libraries instead? (4.1)

5. I took the tlast generator from the 233 Example of Adam Taylors MicroZed chronicles.  It is just generating a tlast signal for AXI Stream to work between XADC and DMA. Adam Taylor referenced a Xilinx example and I borrowed the IP there. According to him I included a GPIO pin to control packet length of the tlast signal. How do I access this GPIO? (5.1)

I would be grateful for any help and answers to my questions and I hope this is the right place. If there are any documents that would help me, please point me in the right direction.

This is my first FPGA/SoC project and I plan to include a VHDL block for integration of the ADC values when I get this minimal example to work.

I have a bit of trouble in sorting all the new knowledge and knowing where to look for solving these broad problems.

Thank you very much in advance!

DrF16

 

[Ana-Maria Balas]

Hello @DrF16,

1. You can program the board, also you can store the application by programing the Flash memory or store the application to SD card, each way is done through JTAG using the USB-JTAG cable.

This video  https://www.youtube.com/watch?v=EW_7Uhjx3TE shows how you can program any application to Flash memory, then you have to enable QSPI from the Programming mode jumper JP5.

To store the application to SD card, the steps are the same for creating the BOOT.bin file, then you just have to copy the BOOT.bin file to sd card, insert it into the board and before power-on the board you have enable MicroSD from the Programming mode jumper JP5 ( read the Reference manual for programming https://reference.digilentinc.com/reference/programmable-logic/zybo-z7/reference-manual#zynq_configuration )

I recommend you to use a Vivado version with SDK (like 2019.1), before using Vitis, because you are a beginner and the Vitis appeared a few months ago and there aren't many tutorials to explain how to do things in Vitis.

For SDK you can find a lot of forum discussions, tutorials, even the Digilent tutorials are made in SDK for now.

2. If you read the reference manual https://reference.digilentinc.com/reference/programmable-logic/zybo-z7/reference-manual#usb-uart_bridge_serial_port

The FT2232HQ controller is used as USB-UART and USB-JTAG, that is why you see 2 tty ports opened. One is only for programming the board through JTAG and the other one is for serial communication (UART).

Usually the first opened port is for serial communication, in your case /dev/ttyUSB0. Do not make the mistake to assign com port names like ttyUSB0 or ttyUSB1 with the UART channel selected in Zynq. ttyUSB0 ,ttyUSB1, ttyUSB2 and so on, are named by the Linux tty driver, for each com port that is opened in order.

For example you can have 2 other USB devices connected, before you connect the Zybo board, so the tty driver will assign ttyUSB2 and ttyUSB3 for the board. That is why in this case you have to find out which tty port corresponds to the UART port of the board. In this case probably ttyUSB2.

3, 4, 5.For the rest of your questions, you can find the answers in the https://github.com/ATaylorCEngFIET/MicroZed-Chronicles/blob/master/part_233.c regarding how to access gpio, which libraries do you need, how the reset is done and how the transfers occurs.

Check each function what it does and I'm sure you'll understand.

Also maybe you can find some inspiration and answers if you take a look at the

Zybo DMA Audio Demo: https://reference.digilentinc.com/learn/programmable-logic/tutorials/zybo-dma-audio-demo/start

Please look into the HW project and SDK sources.