Chapter 4 Working with the Cortex®-M3 DesignStart™ example design
This chapter describes how to work with an example design targeting a low-cost evaluation board, Digilent Arty Artix 7 (A7). This example design is provided to demonstrate the integration and software development using the Cortex®-M3 processor. The example is based on the Digilent Arty A7-35T board, and uses some of the standard Xilinx peripherals to connect to some of the features on the board. The example is intended to show typical usage, rather than a completely minimal Cortex-M3 processor design.
The board provides the Digilent Pmod™ peripheral module headers for peripherals, and shield expansion headers to support additional expansion. You can use the optional Arm V2C-DAPLink board with these headers to use Cortex-M3 for easy debug and software development. If you do not use the V2C-DAPLink board, you can still connect a Serial Wire Debug (SWD) probe (Arm® Keil® ULINK™ or similar) to J4 (nSRST on I/O, SWDIO on I/O, and SWCLK on I/O).
Some features of the example design detect the presence of the V2C-DAPLink board, and adapt accordingly. The V2C-DAPLink board includes pass-through headers for an additional shield board to be connected on top.
The block diagram of the design is available in
The example design has the following functions:
UART to output to either the Arty onboard USB connector, or the V2C-DAPLink board, when fitted.
- GPIO_0 connected to the four DIP switches, SW[3:0], and the four green LEDs LD[7:4].
- GPIO_1 connected to the four push button switches, BTN[3:0], and the four multicolor LEDs.
- QSPI_0 connected to the Arty on-board Quad Serial Port Interface (QSPI) flash memory.
- BRAM ctrl 0 connected to 64KB of internal FPGA BRAM.
The following peripherals are connected to the V2C-DAPLink adaptor board using J4.
- QSPI 1 connected to the adaptor board QSPI flash memory.
- SPI 0 connected to the adaptor board SD card memory.
A number of pre-built files are provided with the example design. For more information, see Example design reference files.
NoteThe example design files are modified by the Vivado tool when you open the design, so it might be useful to copy the
/hardwaredirectory before working with it. For more information on the directory structure, see Directory structure.
It contains the following sections: