AXI Uartlite學習（二）UART LOOP

硬件平臺：Zedboard

軟件環境：Vivado 2015.2 

參考例程：xuartlite_low_level_example.c

//*****************************************************************

一、UART LOOP工程介紹

    本節要在PL中使用AXI Uartlite這個串口IP。這個工程須要物理上有一個UART LOOP，也就是說Uartlite的TX管腳發出去數據，還要有一個外設接收數據並回傳到RX管腳，造成一個迴路。然而Zedboard只在PS的管腳上拓展一個串口外設，PL管腳是沒有的。所以首先要作一個IP，實現串口數據環路。工程Block Design如圖1。

   

圖1 Block Design

二、uart_loop

    這個本身作的IP的功能就是接收Uartlite TX管腳發送的數，轉發到RX管腳。代碼以下：

`timescale 1ns / 1ps

//////////////////////////////////////////////////////////////////////////////////

// Company: 

// Engineer: 

// 

// Create Date: 2016/08/26 15:42:28

// Design Name: 

// Module Name: uart_loop

// Project Name: 

// Target Devices: 

// Tool Versions: 

// Description: 

// 

// Dependencies: 

// 

// Revision:

// Revision 0.01 - File Created

// Additional Comments:

// 

//////////////////////////////////////////////////////////////////////////////////

 

 

module uart_loop #(

    parameter WIDTH_D = 8)

    (

    input wire CLK,     //110M

    input wire RX,

    output wire TX

    );

    //

    wire dv;

    wire [WIDTH_D-1:0] dout;

    wire rfd;

    UAR_115200 uar_inst(

        .CLK(CLK),

        .DI(RX),

        //

        .DV(dv),

        .DO(dout)

    );

    //

    UAT_115200 uat_inst(

        .CLK(CLK),

        .DIN(dout),

        .ND(dv&rfd),

        //

        .DOUT(TX),

        .RFD(rfd)

    );

    

endmodule

//***********************************************************************************

三、SDK源碼

/******************************************************************************

*

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/*****************************************************************************/

/**

*

* @file xuartlite_low_level_example.c

*

* This file contains a design example using the low-level driver functions

* and macros of the UartLite driver (XUartLite).

*

* @note

*

* The user must provide a physical loopback such that data which is

* transmitted will be received.

*

* MODIFICATION HISTORY:

* <pre>

* Ver   Who  Date Changes

* ----- ---- -------- ---------------------------------------------------------

* 1.00b rpm  04/25/02 First release

* 1.00b sv   06/13/05 Minor changes to comply to Doxygen and coding guidelines

* 2.00a ktn  10/20/09 Updated to use HAL processor APIs and minor changes

*      for coding guidelines.

* </pre>

******************************************************************************/

 

/***************************** Include Files *********************************/

 

 

#include "xparameters.h"

#include "xstatus.h"

#include "xuartlite_l.h"

#include "xil_printf.h"

/************************** Constant Definitions *****************************/

 

 

/*

 * The following constants map to the XPAR parameters created in the

 * xparameters.h file. They are defined here such that a user can easily

 * change all the needed parameters in one place.

 */

#define UARTLITE_BASEADDR   XPAR_UARTLITE_0_BASEADDR

 

/*

 * The following constant controls the length of the buffers to be sent

 * and received with the UartLite, this constant must be 16 bytes or less so the

 * entire buffer will fit into the transmit and receive FIFOs of the UartLite.

 */

#define TEST_BUFFER_SIZE 16

 

 

/**************************** Type Definitions *******************************/

 

 

/***************** Macros (Inline Functions) Definitions *********************/

 

 

/************************** Function Prototypes ******************************/

 

int UartLiteLowLevelExample(u32 UartliteBaseAddress);

void Wait(int num);

 

/************************** Variable Definitions *****************************/

 

/*

 * The following buffers are used in this example to send and receive data

 * with the UartLite.

 */

u8 SendBuffer[TEST_BUFFER_SIZE]; /* Buffer for Transmitting Data */

u8 RecvBuffer[TEST_BUFFER_SIZE]; /* Buffer for Receiving Data */

 

 

/*****************************************************************************/

/**

*

* Main function to call the example.

*

* @param None.

*

* @return XST_SUCCESS if successful, XST_FAILURE if unsuccessful.

*

* @note None.

*

******************************************************************************/

int main(void)

{

int Status;

xil_printf("hello world\r\n");

 

 

 

XUartLite_SetControlReg(UARTLITE_BASEADDR, 0x3);

 

 

 

/*

* Run the UartLite Low level example, specify the BaseAddress that is

* generated in xparameters.h.

*/

 

 

Status = UartLiteLowLevelExample(UARTLITE_BASEADDR);

if (Status != XST_SUCCESS) {

return XST_FAILURE;

}

 

 

return XST_SUCCESS;

}

 

 

/*****************************************************************************/

/**

*

* This function does a minimal test on the UartLite device using the low-level

* driver macros and functions. This function sends data and expects to receive

* the data through the UartLite. A physical loopback must be done by the user

* with the transmit and receive signals of the UartLite.

*

* @param UartliteBaseAddress is the base address of the UartLite device

* and is the XPAR_<UARTLITE_instance>_BASEADDR value from

* xparameters.h.

*

* @return XST_SUCCESS if successful, XST_FAILURE if unsuccessful.

*

* @note None.

*

******************************************************************************/

int UartLiteLowLevelExample(u32 UartliteBaseAddress)

{

int Index;

 

/*

* Initialize the send buffer bytes with a pattern to send and the

* the receive buffer bytes to zero.

*/

for (Index = 0; Index < TEST_BUFFER_SIZE; Index++) {

//SendBuffer[Index] = Index + 'B';

SendBuffer[Index] = Index+1;

RecvBuffer[Index] = 0;

}

 

 

/*

* Send the entire transmit buffer.

*/

for (Index = 0; Index < TEST_BUFFER_SIZE; Index++) {

XUartLite_SendByte(UartliteBaseAddress, SendBuffer[Index]);

// Wait(10000);

 

}

 

/*

* Receive the entire buffer's worth. Note that the RecvByte function

* blocks waiting for a character.

*/

for (Index = 0; Index < TEST_BUFFER_SIZE; Index++) {

RecvBuffer[Index] = XUartLite_RecvByte(UartliteBaseAddress);

xil_printf("RecvBuffer[%d] is %d\r\n",Index,RecvBuffer[Index]);

}

 

/*

* Check the receive buffer data against the send buffer and verify the

* data was correctly received.

*/

for (Index = 0; Index < TEST_BUFFER_SIZE; Index++) {

 

if (SendBuffer[Index] != RecvBuffer[Index]) {

return XST_FAILURE;

}

}

 

 

return XST_SUCCESS;

}

 

void Wait(int num)

{

int i;

for(i=0;i<num;i++)

{}

 

}

 

四、實驗現象及分析

    咱們發送的是1~16共16個數，從圖2中SDK Console窗口看的打印信息，只有1,3,5,7,9,11,13,15，圖3爲HW Debug中觀察PS發送給PL的數據，可見的確是發送了16個數據，分析多是uart_loop模塊收發串口數據耽誤了時間，增長一個延時函數，PS向PL發送一個數據後，延時一段時間，問題獲得解決，如圖4。

   

圖2 SDK Console窗口打印信息

圖3 HW Debug窗口

圖4 添加延時函數後SDK Console窗口打印信息

轉載鏈接：http://www.eefocus.com/mastershifu2015/blog/16-08/389822_f4618.html