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  2. Topic: Configuring ZYNQ7 Processing System

Configuring ZYNQ7 Processing System

Setting up Zynq Processing system to use SPI,I2C, and UART modules

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ZYNQ7 Processing System Configuration

This short tutorial will walk you through on how you can configure ZYNQ7 processing system so that MIO pins would be used for certain peripherals, such as SPI,I2C, and UART.

Setting up MIO pins for I2C, SPI, and UART

Open up ZYNQ7 Processing System by double clicking on the IP block.

Figure 1. Open ZYNQ7 Processing System
Figure 1. Open ZYNQ7 Processing System

Click on Peripheral MIO Pins. You will then see a window as show in figure 2, where some peripherals are already configured and other’s aren’t.

Figure 2. Peripheral IO Pins
Figure 2. Peripheral IO Pins

Step 1: I2C1 Configuration

In order to configure the I2C MIO pins, you need to find out on what pins the I2C bus is connected to. From figure 3, you can see that TEMP_SCL and TEMP_SDA are connected to MIO pins 20 and 21, respectively. You can also see from the figure that TEMP_OS (interrupt signal) is connected to MIO pin 24.

Figure 3. Blackboard Schematic for Bank 1 MIO Pins (I2C)
Figure 3. Blackboard Schematic for Bank 1 MIO Pins (I2C)

Use the top array of MIO pin numbers to find the correct pins for the I2C as shown in figure 4. You will notice that there is only one I2C bus (I2C1) under MIO pins 20 and 21.

Figure 4. Locating I2C MIO Pins
Figure 4. Locating I2C MIO Pins

Click on I2C1 button as shown in figure 5 (The button should turn green).

Figure 5. Enabling I2C1 on MIO pins 20 and 21
Figure 5. Enabling I2C1 on MIO pins 20 and 21

Click on the small arrow on the I2C 1 peripheral to configure the interrupt under MIO pin 24.

Figure 6. Configuring Interrupt for I2C 1 Bus
Figure 6. Configuring Interrupt for I2C 1 Bus

Step 2: Configuring SPI0 bus as an EMIO

Since SPI0 pins can only be connected through the FPGA, you need to configure SPI0 as EMIO (External MIO). This functionality simply enables you to use the SPI0 bus in the ZYNQ7 processing system through the FPGA. Click on the EMIO button in the end of the SPI0 line to enable the EMIO pins. Later on you will make the connections to the FPGA from the block design (.XDC file).

Figure 7. Configuring SPI0 as EMIO
Figure 7. Configuring SPI0 as EMIO

Step 3: UART1 Configuration

In order to configure the UART MIO pins, you need to find out on what pins the UART bus is connected to. From figure 8, you can see that UART_RXD_OUT and UART_TXD_IN are connected to MIO pins 48 and 49, respectively.

Figure 8. Blackboard Schematic for Bank 1 MIO Pins (UART1)
Figure 8. Blackboard Schematic for Bank 1 MIO Pins (UART1)

Locate UART 1 pins 48 and 49 like you did for I2C. Click on the UART1 button as shown in figure 9 to configure the MIO pins 48 and 49 to be used as UART1.

Figure 9. UART1 MIO pin configuration
Figure 9. UART1 MIO pin configuration

Step 4: Configure FCLK_CLK0 Clock Frequency

Click on Clock configuration and then on PL Fabric Clocks. Change the FCLK_CLK0 frequency to 100MHz as shown in figure 10. The FCLK_CLK0 is ued to determine the frequency for the AXI interface.

Figure 10. FCLK_CLK0 Configuration
Figure 10. FCLK_CLK0 Configuration

Step 5: Save Configuration for Future Use

Click on Presets and then choose Save Configuration…. Choose a desired location to save the new configuration as a .tcl file that you can possibly use for future projects. After you’ve saved the configuration, press OK.

Figure 11. FCLK_CLK0 Configuration
Figure 11. FCLK_CLK0 Configuration

Step 6: Finish SPI0 Configuration

To configure SPI Master Controller through EMIO pins, you need to follow the diagram in figure 12. (Figure 12 is acquired from UG585-Zynq-7000-TRM under SPI Section; figure 17-8).

Figure 12. SPI wiring diagram for Master mode via EMIO pins
Figure 12. SPI wiring diagram for Master mode via EMIO pins

You’ll notice that your ZYNQ7 IP block has changed. Click on the + sign right next to SPI0 as shown in figure 13.

Figure 13. SPI0 on Zynq7
Figure 13. SPI0 on Zynq7

Right click anywhere on the white space and press Add IP…

Figure 14. Add IP
Figure 14. Add IP

Search for Constant as shown in figure 15 and click on it.

Figure 15. Add Constant IP Core
Figure 15. Add Constant IP Core

Constant IP core has been placed to your block design. Next, change the name of this IP Core in your block diagram by clicking once on the IP Core and you will see a diagram in the bottom left named Block Properties.

Figure 16. Add Constant IP Core
Figure 16. Add Constant IP Core

Change the name to GND from the block properties.

Figure 17. Changing the name of the Block
Figure 17. Changing the name of the Block

Now double click on the IP block GND. Change the Constant value to 0.

Figure 18. Changing the value of block GND
Figure 18. Changing the value of block GND

Connect dout of the GND block as shown in figure 19 to the SPI0 EMIO pins.

Figure 19. Connecting GND Block to the System
Figure 19. Connecting GND Block to the System

Add another Constant IP Core and name it VDD. Make sure that the constant value is 1. Then connect it to the rest of the system as shown in figure 20.

Figure 20. Connecting VDD Block to the System
Figure 20. Connecting VDD Block to the System

Since there is only one MISO line under the SPI0 EMIO pins and two MISO lines for the NAV sensor, you need to create a module that would choose the correct MISO line for data transfer based on the correct Slave Select Line. Create a new module under design sources and name it slave_select. Copy the following code to the new module you created.

`timescale 1ns / 1ps
module slave_select(
    input MISO_A_G,
    input MISO_M,
    input SS_A_G, // SS for accelerometer and Gyroscope
    input SS_M, // magnetic sensor SS
    output reg MISO = 0
    );
    
always@(SS_A_G,SS_M,MISO_A_G,MISO_M)
begin
    if (~SS_A_G && SS_M) MISO = MISO_A_G;
    else if (SS_A_G && ~SS_M) MISO = MISO_M;
    else MISO = 0; 
end
endmodule

Right click on the module you created (slave_select) and choose Add Module to Block Design.

Figure 21. Adding slave_select module to Block Design
Figure 21. Adding slave_select module to Block Design

Connect the MISO, SS_A_G, and SS_M lines to the ZYNQ7 Processing System as shown in figure 22.

Figure 22. Connecting slave_select to the rest of the system
Figure 22. Connecting slave_select to the rest of the system

Right click anywhere on the white space and select Create Port.

Figure 23. Create a Port
Figure 23. Create a Port

Create Port Dialog will appear. Name the port as SS_A_G, set the direction as Output, and type as data. Press OK

Figure 24. Create a Port Dialog
Figure 24. Create a Port Dialog

Create another port named SS_M similar to how you created SS_A_G. Connect these ports to the rest of the system as shown in figure 25.

Figure 25. Create a Port Dialog
Figure 25. Create a Port Dialog

Next, create appropriate ports for MISO_A_G, MISO_M, SPI0_SCLK_O, and SPI_MOSI_O. Finish your design by updating the constraints .XDC file for the SPI0 bus.

Where to find information about I/O Constraints

You can find the location you need from the Blackboard, or you can download the Blackboard master XDC for your board from the Real Digital®’s website and copy the corresponding lines for this step.

Step 7: Run Synthesis, Implementation, and Generate Bitstream.