嵌入式开发就业前景seo兼职外包
1、背景介绍
复旦微ZYNQ通过SPI配置国产JEM5396，框图如下：
现在需要在linux下的应用程序内配置JEM5396的寄存器。其中FMQL和进口的XILINX ZYNQ类似，JEM5396和进口的BCM5396兼容。因此可以参考进口ZYNQ在linux下配置BCM5396过程。Zynq-Linux移植学习笔记之41-linux下通过SPI访问broadcom 5396交换芯片_bcm5396-CSDN博客
2、内核配置
内核中将spidev.c编到内核内，同时在spidev.c中添加jem5396设备
3、设备树配置
设备树中在spi节点下添加jem5396设备
4、应用修改
由于复旦微FMQL中采用的SPI控制器不是SPI-CADENCE IP，所以不需要和进口ZYNQ那样改驱动。但是需要在应用APP中修改。参考JEM5396提供的差异说明
我司配套SPI驱动：使用ARM STM32F107VC型芯片内建的SPI IP实现SPI Master与5396 SPI Slave的通信。配置时需注意以下几点：
１．经过测试，5396 spi的CPHA选择必须为2Egde（CPOL可以为High或Low），才能保证与5396正常通信。
2. 由于内部设计原因导致spi接口的cs控制与sck时钟信号，两者可能出现信号对齐或大体重合，继而导致采样数据不准。因此，在时序上需要 cs触发后的第一个时钟沿向后延几个相位。如红框图位置
应用代码如下：
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/spi/spidev.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>#define NREAD (0x60)
#define NWRITE (0x61)#define SIO (0xF0)
#define STS (0xFE)
#define SPG (0xFF)#define SPIF (0x80)
#define RACK (0x20)
#define RXRDY (0x02)
#define TXRDY (0x01)uint8_t mode = SPI_CPHA|SPI_CPOL;
uint8_t bits = 8;
uint32_t speed = 2000000;
uint16_t delay=0;unsigned int readBCM5396Reg(unsigned char page,unsigned char offset,unsigned char regType)
{unsigned char wr_buf[32],rd_buf[32],*bp;int len, status;struct spi_ioc_transfer xfer[2];int file;unsigned int result;int ret=0;file = open("/dev/spidev2.0", O_RDWR);if (file<0) {printf("open 5396 error\n");return 1;}if (ioctl(file, SPI_IOC_WR_MODE, &mode) < 0){printf("SPI_IOC_WR_MODE failed\n");}if (ioctl(file, SPI_IOC_RD_MODE, &mode) < 0){printf("SPI_IOC_RD_MODE failed\n");}memset(wr_buf, 0, sizeof(wr_buf));memset(rd_buf, 0, sizeof(rd_buf));memset(xfer,0,sizeof(xfer));wr_buf[0] = NREAD;wr_buf[1] = STS;xfer[0].tx_buf = (unsigned long) wr_buf;xfer[0].rx_buf = (unsigned long) rd_buf;xfer[0].len = 3;status = ioctl(file, SPI_IOC_MESSAGE(1), xfer);printf("#1 status is %d\n",status);usleep(10000);printf("#1 NREAD response(%d): ", status);for (bp = rd_buf; len; len--)printf("%02x ", *bp++);printf("\n");wr_buf[0] = NWRITE;wr_buf[1] = SPG;wr_buf[2] = page;xfer[0].tx_buf = (unsigned long) wr_buf;xfer[0].rx_buf = (unsigned long) rd_buf;xfer[0].len = 3;status = ioctl(file, SPI_IOC_MESSAGE(1), xfer);//printf("#2 status is %d\n",status);//usleep(10000);printf("#2 NWRITE response(%d): ", status);for (bp = rd_buf; len; len--)printf("%02x ", *bp++);printf("\n");wr_buf[0] = NREAD;wr_buf[1] = offset;xfer[0].tx_buf = (unsigned long) wr_buf;xfer[0].rx_buf = (unsigned long) rd_buf;xfer[0].len = 3;status = ioctl(file, SPI_IOC_MESSAGE(1), xfer);//printf("#3 status is %d\n",status);//usleep(10000);printf("#3 NREAD response(%d): ", status);for (bp = rd_buf; len; len--)printf("%02x ", *bp++);printf("\n");wr_buf[0] = NREAD;wr_buf[1] = STS;xfer[0].tx_buf = (unsigned long) wr_buf;xfer[0].rx_buf = (unsigned long) rd_buf;xfer[0].len = 3;status = ioctl(file, SPI_IOC_MESSAGE(1), xfer);//printf("#4 status is %d\n",status);//usleep(10000);printf("#4 NREAD response(%d): ", status);for (bp = rd_buf; len; len--)printf("%02x ", *bp++);printf("\n");wr_buf[0] = NREAD;wr_buf[1] = SIO;xfer[0].tx_buf = (unsigned long) wr_buf;xfer[0].rx_buf = (unsigned long) rd_buf;xfer[0].len = 2+regType/8;status = ioctl(file, SPI_IOC_MESSAGE(1), xfer);//printf("#5 status is %d\n",status);len=status;if (status < 0) {perror("SPI_IOC_MESSAGE");return -1;}printf("#5 NREAD response(%d): ", status);for (bp = rd_buf; len; len--)printf("%02x ", *bp++);printf("\n");bp = rd_buf;memcpy(&result,bp+2,regType/8);printf("read result is 0x%x\n",result);close(file);return result;
}unsigned int writeBCM5396Reg(unsigned char page,unsigned char offset,unsigned char *pBuffer,unsigned char regType)
{unsigned char wr_buf[32],rd_buf[32],*bp;int len, status;struct spi_ioc_transfer xfer[2];int file,i;unsigned int result;file = open("/dev/spidev2.0", O_RDWR);if (file<0) {printf("open 5396 error\n");return 1;}if (ioctl(file, SPI_IOC_WR_MODE, &mode) < 0){printf("SPI_IOC_WR_MODE failed\n");}if (ioctl(file, SPI_IOC_RD_MODE, &mode) < 0){printf("SPI_IOC_RD_MODE failed\n");}memset(wr_buf, 0, sizeof(wr_buf));memset(rd_buf, 0, sizeof(rd_buf));memset(xfer,0,sizeof(xfer));wr_buf[0] = NREAD;wr_buf[1] = STS;xfer[0].tx_buf = (unsigned long) wr_buf;xfer[0].rx_buf = (unsigned long) rd_buf;xfer[0].len = 3;status = ioctl(file, SPI_IOC_MESSAGE(1), xfer);wr_buf[0] = NWRITE;wr_buf[1] = SPG;wr_buf[2] = page;xfer[0].tx_buf = (unsigned long) wr_buf;xfer[0].rx_buf = (unsigned long) rd_buf;xfer[0].len = 3;status = ioctl(file, SPI_IOC_MESSAGE(1), xfer);wr_buf[0] = NWRITE;wr_buf[1] = offset;for(i=0;i<regType/8;i++){wr_buf[2+i] = pBuffer[i];}xfer[0].tx_buf = (unsigned long) wr_buf;xfer[0].rx_buf = (unsigned long) rd_buf;xfer[0].len = 2+(regType/8);status = ioctl(file, SPI_IOC_MESSAGE(1), xfer);close(file);return status;
}int main()
{unsigned int temp;unsigned char buf[10];int res=0;buf[0]=0x00;buf[1]=0x0f;buf[2]=0x00;temp=readBCM5396Reg(0x2,0x30,32);printf("page 0x2 offset 0x30 is 0x%x\n",temp);sleep(1);//连续读之间需要加时延temp=readBCM5396Reg(0x31,0x00,32);printf("before write page 0x31 offset 0x0 is 0x%x\n",temp);res=writeBCM5396Reg(0x31, 0x00, buf,32);//Port 0 - Slot 10if(res<0){printf("write bcm5396 error\n");}temp=readBCM5396Reg(0x31,0x00,32);printf("after write page 0x31 offset 0x0 is 0x%x\n",temp);return 0;
}
5、测试验证
系统启动后，执行应用，可以看到能够正常读写
注意：国产JEM5396在连续读写寄存器时存在问题，连续两次读之间需要加1s延迟。具体看应用示例。
另外，调试时发现有个小工具很好用spidev_test，这样就不需要自己写代码，直接模拟SPI读写时序
spidev_test -D /dev/spidev2.0 -s 2000000 -H -O -p "\x60\xFE\x00" -v #NREAD,STS,rd_sts_spif(0x00)spidev_test -D /dev/spidev2.0 -s 2000000 -H -O -p "\x61\xFF\x02" -v #NWRITE,SPG,page(0x02)spidev_test -D /dev/spidev2.0 -s 2000000 -H -O -p "\x60\x30\x00" -v #NREAD,reg(0x30),rd_nonespidev_test -D /dev/spidev2.0 -s 2000000 -H -O -p "\x60\xFE\x00" -v #NREAD,STS,rd_sts_rack(0xA0)spidev_test -D /dev/spidev2.0 -s 2000000 -H -O -p "\x60\xF0\x00" -v #NREAD,SIO,rd_5396_id(0x60)
上图为读出JEM5396的ID操作
Spidev_test具体用法如下：
当然，使用这个工具的前提是有个正确的时序，然后通过spidev_test去实现这个时序，比如spidev_test中设置-H（配置CPHA）和-O（配置CPOL），这个与芯片说明中的“经过测试，5396 spi的CPHA选择必须为2Egde（CPOL可以为High或Low），才能保证与5396正常通信 ”描述一致。