其中用到了SPI_IOC_MESSAGE,这是一个非常重要的ioctl()请求,用于执行实际的SPI数据传输。该命令允许应用程序在单个调用中执行一个或多个SPI消息的完整传输。 参数结构:spi_ioc_transfer 该命令通常与一个或多个spi_ioc_transfer结构体一同使用。每个spi_ioc_transfer结构体都描述了一个独立的SPI传输消息,包括以下几...
if ((tmp %sizeof(struct spi_ioc_transfer)) != 0) {//判断是否为spi_ioc_transfer对齐 retval = -EINVAL; break; } n_ioc = tmp /sizeof(struct spi_ioc_transfer);//计算出spi_ioc_transfer数据的个数 if (n_ioc == 0) break; ioc = kmalloc(tmp, GFP_KERNEL);//分配spi_ioc_transfer指针...
//使用到的宏SPI_IOC_RD_MAX_SPEED_HZ SPI_IOC_WR_MAX_SPEED_HZ//伪代码/*读取字长*/u8 bits; fd =open("/dev/spidevx.y",O_RDWR);if(ioctl(fd, SPI_IOC_RD_LSB_FIRST, &bits) <0) { perror("SPI rd_lsb_fist");return; }/*设置字长*/if(ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &b...
transfer.delay_usecs = 0; transfer.speed_hz = configuration.speed; transfer.bits_per_word = configuration.bits; transfer.cs_change = flags & SPI_Flag_CSChange; // Execute transfers status = ioctl(handle, SPI_IOC_MESSAGE(1), &transfer); ...
SPI_IOC_MESSAGE(N)を使う。Nは一度に転送するspi_ioc_transferの個数。 読み書きの例 #define HOGE_SPI_SPEED_HZ 1000000 #define HOGE_SPI_DELAY_USECS 0 #define HOGE_SPI_BITS 8uint8_ttx[3]={1,2,3};uint8_trx[3]={0,};structspi_ioc_transfertr[1];tr[0].tx_buf=(unsignedlong)tx;...
因为采用的ioctl的SPI_IOC_MESSAGE(1)是全双工,read和write是半双工,如果要让read为全双工,read出来才是,回环的数据,即需要修改内核里面spidev.c里面的spidev_sync_read函数,spi_transfer结构体需加上.tx_buf = spidev->tx_buffer,即可。 2022-7-19 15:44:13 评论 举报 siyugege 提交评论 撰写答案...
m_spi_transfer[0].bits_per_word = 16; ... rv = ioctl(spidev_fd, SPI_IOC_MESSAGE(1), m_spi_transfer); Here is my SPI configuration: SPI Dev Configuration SPI Dev Path: /dev/spid 32-bit Read Mode: 3 LSB First: no Bits Per Word: 16 ...
spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc, unsigned *n_ioc) { u32 tmp; /* Check type, command number and direction */ if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0)) ...
{ close(fd); return -4; } return fd; } int spiClose(int fd) { return close(fd); } int spiRead(int fd, unsigned speed, char *buf, unsigned count) { int err; struct spi_ioc_transfer spi; memset(&spi, 0, sizeof(spi)); spi.tx_buf = (unsigned) NULL; spi.rx_buf = (unsign...
I have been debugging strange interactions between a Xavier NX and a SPI-controlled IMU. When I transfer a single word, such as 16-bits at a time the IMU behaves normally: The IMU has a feature that allows the user …