DMA transfer

About this tutorial

⏱️ 45 min

Key learnings:

• Long custom waveform generation generation/acquisition.

• PL (Programable Logic): use AXI DMA IP for reading/writing data from/to RAM memory.

• PS (Processing System): use PYNQ for reading/writing data from/to RAM memory.

Description:

FPGAs have typically very low on-chip memory resources (~250kB for the ZYNQ-7010 of your Redpitaya-125-14). This limitation is circumvented through one (or several) external DDR memories which are connected to the FPGA through high bandwidth ports and controlled through a Direct Memory Access (DMA) engine. The Redpitaya-125-14 includes a 512MB DDR memory, which serves as RAM for the Zynq PS but can also be used to exchange data with the Zynq PL.

In this tutorial we are going to build a dual channel data acquisition and generation design, where the samples are directly read form (written to) RAM memory via DMA. A PYNQ Jupyter Notebook will be used to preload a waveform to RAM memory for waveform generation, simultaneously trigger the waveform generation/acquisition and plot the acquired samples.

Building the Vivado Design

Create a new Vivado Project

Follow the steps in LED blink and use DMA_transfer as the new project name.

Import the Redpitaya-125-14 IP library

Follow the steps in Analog echo