AXI Uartlite学习（二）UART LOOP
硬件平台：Zedboard
软件环境：Vivado 2015.2
参考例程：xuartlite_low_level_example.c
//*****************************************************************
1、UART LOOP工程介绍
本节要在PL中使用AXI Uartlite这个串口IP。这个工程需要物理上有一个UART LOOP，也就是说Uartlite的TX管脚发出去数据，还要有一个外设接收数据并回传到RX管脚，形成一个回路。然而Zedboard只在PS的管脚上拓展一个串口外设，PL管脚是没有的。因此首先要做一个IP，实现串口数据环路。工程Block Design如图1。
图1 Block Design
2、uart_loop
这个自己做的IP的功能就是接收Uartlite TX管脚发送的数，转发到RX管脚。代码如下：
`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
//***********************************************************************************
3、SDK源码
/******************************************************************************
*
* (c) Copyright 2002-2013 Xilinx, Inc. All rights reserved.
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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:
*
* 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.
*
******************************************************************************/
/***************************** 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__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
{}
}
4、实验现象及分析
我们发送的是1~16共16个数，从图2中SDK Console窗口看的打印信息，只有1,3,5,7,9,11,13,15，图3为HW Debug中观察PS发送给PL的数据，可见的确是发送了16个数据，分析可能是uart_loop模块收发串口数据耽误了时间，增加一个延时函数，PS向PL发送一个数据后，延时一段时间，问题得到解决，如图4。
图2 SDK Console窗口打印信息
图3 HW Debug窗口
图4 添加延时函数后SDK Console窗口打印信息
转载连接：http://www.eefocus.com/mastershifu2015/blog/16-08/389822_f4618.html