平台 | 内核版本 | 安卓版本 |
---|---|---|
RK3399 | Linux4.4 | Android7.1 |
文章目录
SPI初始化
首先定义spi
工作模式、传输位数、传输速度等:
static const char *device = "/dev/spidev32766.0";
static uint8_t mode = 3; /* SPI通信使用全双工,设置CPOL=1,CPHA=1。 */
static uint8_t bits = 8; /* 8bits读写,MSB first。*/
static uint32_t speed = 24 * 1000 * 1000;/* 设置12M传输速度 */
static uint16_t delay = 0;
接下来就开始操作总线将其初始化,其中重要的IOCTL
命令如下:
命令 | 解析 |
---|---|
SPI_IOC_WR_MODE |
SPI模式设置可写 |
SPI_IOC_RD_MODE |
SPI模式设置可读 |
SPI_IOC_WR_BITS_PER_WORD |
SPI的bit/word设置可写 |
SPI_IOC_RD_BITS_PER_WORD |
SPI的bit/word设置可读 |
SPI_IOC_WR_MAX_SPEED_HZ |
SPI的波特率设置可写 |
SPI_IOC_RD_MAX_SPEED_HZ |
SPI的波特率设置可读 |
/**
* 功 能:打开设备 并初始化设备
* 入口参数 :
* 出口参数:
* 返回值:0 表示已打开 0XF1 表示SPI已打开 其它出错
*/
int SPI_Init(void)
{
int fd;
int ret = 0;
//mode=SPI_MODE_0;
if (g_SPI_Fd != 0) /* 设备已打开 */
return 0xF1;
fd = open(device, O_RDWR);
if (fd < 0)
pabort("can't open device");
else
printf("SPI - Open Succeed. Start Init SPI...\n");
g_SPI_Fd = fd;
/*
* spi mode
*/
ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);
if (ret == -1)
pabort("can't set spi mode");
ret = ioctl(fd, SPI_IOC_RD_MODE, &mode);
if (ret == -1)
pabort("can't get spi mode");
/*
* bits per word
*/
ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
if (ret == -1)
pabort("can't set bits per word");
ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);
if (ret == -1)
pabort("can't get bits per word");
/*
* max speed hz
*/
ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
if (ret == -1)
pabort("can't set max speed hz");
ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);
if (ret == -1)
pabort("can't get max speed hz");
printf("spi mode: %d\n", mode);
printf("bits per word: %d\n", bits);
printf("max speed: %d KHz (%d MHz)\n", speed / 1000, speed / 1000 / 1000);
return ret;
}
SPI 自发自收测试程序
/**
* 功 能:自发自收测试程序
* 接收到的数据与发送的数据如果不一样 ,则失败
* 说明:
* 在硬件上需要把输入与输出引脚短跑
*/
int SPI_LookBackTest(void)
{
int ret, i;
const int BufSize = 16;
uint8_t tx[BufSize], rx[BufSize];
bzero(rx, sizeof(rx));
for (i = 0; i < BufSize; i++)
tx[i] = i;
printf("\nSPI - LookBack Mode Test...\n");
ret = SPI_Transfer(tx, rx, BufSize);
if (ret > 1)
{
ret = memcmp(tx, rx, BufSize);
if (ret != 0)
{
printf("LookBack Mode Test error\n");
//pabort("error");
}
else
printf("SPI - LookBack Mode OK\n");
}
return ret;
}
spi_ioc_transfer
(用户层对一些属性消息的封装,和内核中spi_transfer
基本一样,少了一些成员)
/**
* 功 能:同步数据传输
* 入口参数 :
* TxBuf -> 发送数据首地址
* len -> 交换数据的长度
* 出口参数:
* RxBuf -> 接收数据缓冲区
* 返回值:0 成功
*/
int SPI_Transfer(const uint8_t *TxBuf, uint8_t *RxBuf, uint32_t len)
{
int ret;
int fd = g_SPI_Fd;
struct spi_ioc_transfer tr ={
.tx_buf = (unsigned long) TxBuf,
.rx_buf = (unsigned long) RxBuf,
.len = len,
.speed_hz = speed,
.delay_usecs = delay,
.bits_per_word = bits,
.cs_change = 0,
.tx_nbits = 8,
.rx_nbits = 8,
.pad = 0,
};
ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
if (ret < 1)
printf("can't send spi message");
else
{
#if SPI_DEBUG
int i;
printf("nsend spi message Succeed");
printf("nSPI Send [Len:%d]: ", len);
for (i = 0; i < len; i++)
{
if (i % 8 == 0)
printf("nt");
printf("0x%02X ", TxBuf[i]);
}
printf("n");
printf("SPI Receive [len:%d]:", len);
for (i = 0; i < len; i++)
{
if (i % 8 == 0)
printf("nt");
printf("0x%02X ", RxBuf[i]);
}
printf("n");
#endif
}
return ret;
}
SPI读写
/**
* 功 能:发送数据
* 入口参数 :
* TxBuf -> 发送数据首地址
*len -> 发送与长度
*返回值:0 成功
*/
int SPI_Write(uint8_t *TxBuf, int len)
{
int ret;
ret = write(g_SPI_Fd, TxBuf, len);
if (ret < 0)
printf("SPI Write error\n");
#if SPI_DEBUG
else
{
int i;
printf("nSPI Write [Len:%d]: ", len);
for (i = 0; i < len; i++)
{
if (i % 8 == 0)
printf("nt");
printf("0x%02X ", TxBuf[i]);
}
printf("\n");
}
#endif
return ret;
}
/**
* 功 能:接收数据
* 出口参数:
* RxBuf -> 接收数据缓冲区
* rtn -> 接收到的长度
* 返回值:>=0 成功
*/
int SPI_Read(uint8_t *RxBuf, int len)
{
int ret;
int fd = g_SPI_Fd;
ret = read(fd, RxBuf, len);
if (ret < 0)
printf("SPI Read errorn\n");
else
{
#if SPI_DEBUG
int i;
printf("SPI Read [len:%d]:", len);
for (i = 0; i < len; i++)
{
if (i % 8 == 0)
printf("nt");
printf("0x%02X ", RxBuf[i]);
}
printf("\n");
#endif
}
return ret;
}