通过Avalon总线读取sdram数据
时间: 2023-05-23 08:02:41 浏览: 83
可以使用如下的代码:
```
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <linux/types.h>
#include <linux/spi/spidev.h>
#define ARRAY_SIZE(array) sizeof(array)/sizeof(array[0])
#define SPI_PATH "/dev/spidev0.0"
#define SPI_MODE SPI_MODE_0
#define SPI_SPEED_HZ 1000000
#define SPI_BITS_PER_WORD 8
#define AVALON_READ_COMMAND 0xC0
#define SDRAM_SIZE 0x01000000
int main(int argc, char **argv) {
int spi_fd;
uint8_t tx_buffer[4] = { AVALON_READ_COMMAND, 0x00, 0x00, 0x00 };
uint8_t rx_buffer[SDRAM_SIZE];
struct spi_ioc_transfer spi_transfer = {
.tx_buf = (unsigned long)tx_buffer,
.rx_buf = (unsigned long)rx_buffer,
.len = ARRAY_SIZE(tx_buffer),
.delay_usecs = 0,
.speed_hz = SPI_SPEED_HZ,
.bits_per_word = SPI_BITS_PER_WORD,
.cs_change = 0,
.tx_nbits = 0,
.rx_nbits = 0,
.pad = 0,
};
spi_fd = open(SPI_PATH, O_RDWR);
if (spi_fd < 0) {
printf("Failed to open SPI device %s\n", SPI_PATH);
return -1;
}
if (ioctl(spi_fd, SPI_IOC_WR_MODE, &SPI_MODE) < 0) {
printf("Failed to set SPI mode\n");
return -1;
}
if (ioctl(spi_fd, SPI_IOC_WR_BITS_PER_WORD, &SPI_BITS_PER_WORD) < 0) {
printf("Failed to set SPI bits per word\n");
return -1;
}
if (ioctl(spi_fd, SPI_IOC_WR_MAX_SPEED_HZ, &SPI_SPEED_HZ) < 0) {
printf("Failed to set SPI speed\n");
return -1;
}
if (ioctl(spi_fd, SPI_IOC_MESSAGE(1), &spi_transfer) < 1) {
printf("Failed to transfer SPI message\n");
return -1;
}
close(spi_fd);
return 0;
}
```
这个代码是使用C语言编写的,通过 SPI 协议进行通信,读取 SDRAM 的数据。注意,这个代码只是展示了如何使用Avalon总线读取sdram数据,实际使用要根据具体的情况进行修改和调试。