Linux系统CH347应用—SPI功能

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Linux系统CH347应用—SPI功能

 Linux/安卓系统使用CH347转接SPI功能有三种应用方式：

1. 使用CH34X_MPHSI_Master总线驱动为系统扩展原生SPI Master，此方式无需进行单独的应用层编程；

2. 使用CH341PAR_LINUX字符设备驱动，此方式需要配合使用厂商提供的库文件，编程访问设备功能；

3. 使用CH341PAR_ANDROID免驱APP，基于安卓原生USB Host API进行二次开发，此方式无需设备驱动；

基于方式一，可参考如下几篇博客：

基于CH347实现USB扩展SPI/I2C/GPIO Master主机应用方案_扩展spi芯片_PC技术小能手的博客-CSDN博客在安卓/Linux主机上经常会遇到CPU原生SPI/I2C/GPIO Master资源通道不够或者功性能不满足实际产品需求的情况，基于USB2.0高速USB转接芯片CH347，配合厂商提供的USB转MPHSI（Multi Peripheral Serial Line）Master总线驱动（CH34X-MSPI-Master）可轻松实现为系统扩展SPI和I2C总线、GPIO Expander、中断信号等。_扩展spi芯片—SPI设备调试_PC技术小能手的博客-CSDN博客本文介绍，基于USB2.0高速USB转接芯片CH347，配合厂商提供的USB转MPHSI（Multi Protocol High-Speed Serial Interface）Master总线驱动（CH34X-MPHSI-Master）为系统扩展SPI总线的用法，除此之外，还可以扩展I2C总线和GPIO等资源。驱动软件正常工作后，会在系统下创建新的SPI Master，拥有独立的bus num，原SPI器件的设备驱动可直接通过DTS配置文件或者sysfs节点挂载到该总线上，原有设备驱动无需任何修改。：

一、应用框图

二、资源列表

demo：应用软件示例

driver：驱动软件

lib：应用库文件，提供大部分CPU架构的动态库和静态库

三、工作原理

驱动软件正常工作时，会自动在系统/dev目录下创建字符设备，名称为：/dev/ch34x_pis*。基于此节点设备，配合 libch347 动态库，ch347demo应用程序实现对 CH347 芯片的硬件资源的访问。

此方式适用于不需要依赖于原有外设驱动工作的应用场景，使用字符设备实现对于外设的读写功能。类似于串口应用，通过访问 /dev/tty* 设备实现相应设备的：打开、关闭、读写等操作。

四、使用步骤

使用HID驱动模式，直接使用系统自带的 hidraw 驱动即可，使用厂商驱动模式，需要编译使用 CH341PAR_LINUX 资料中driver下的驱动文件，链接地址：

CH341PAR_LINUX.ZIP - 南京沁恒微电子股份有限公司USB转JTAG/SPI/I2C/并口/GPIO等接口的Linux设备驱动程序，支持CH341的USB转SPI/I2C/EPP并口/MEM并口等，支持CH347的480Mbps高速USB转JTAG/SPI/I2C/GPIO等，支持32/64位操作系统。.htmlGitHub - WCHSoftGroup/ch341par_linuxContribute to WCHSoftGroup/ch341par_linux development by creating an account on GitHub.：

 （1）驱动加载

1. unzip CH341PAR.ZIP
2. cd driver
3. sudo make install

插入CH347硬件设备，此时会自动在 /dev 目录下创建字符设备：ch34x_pis*，如下所示：

至此，代表驱动程序和芯片工作正常。

（2）拷贝库文件至系统库路径下，此处以X64 CPU的 ch347 动态库为例：

sudo cp lib/x64/dynamic/libch347.so /usr/lib

（3）应用编程—SPI 主机模式 API介绍

/*** CH347OpenDevice - open device* @pathname: device path in /dev directory** The function return positive file descriptor if successful, others if fail.*/
extern int CH347OpenDevice(const char *pathname);/*** CH347CloseDevice - close device* @fd: file descriptor of device** The function return true if successful, false if fail.*/
extern bool CH347CloseDevice(int fd);/*** CH347SPI_SetDataBits - SPI data bits setting* @fd: file descriptor of device* @iDataBits: 0: 8bit, 1: 16bit ** The function return true if successful, false if fail.*/
extern bool CH347SPI_SetDataBits(int fd, uint8_t iDataBits);/*** CH347SPI_Init - SPI interface initialization* @fd: file descriptor of device* @SpiCfg: pointer to SPI configuration, SPI frequency could be set by SpiCfg->iClock or CH347SPI_SetFrequency API, the latter is preferred** The function return true if successful, false if fail.*/
extern bool CH347SPI_Init(int fd, mSpiCfgS *SpiCfg);/*** CH347SPI_SetChipSelect - SPI chip selection initialization* @fd: file descriptor of device* @iEnableSelect: low 8 bits: CS1, high 8 bits: CS2, byte value -> 1: set CS, 0: ignore CS setting* @iChipSelect: low 8 bits: CS1, high 8 bits: CS2, CS output, byte value -> 1: set CS, 0: cancel CS* @iIsAutoDeativeCS: low 16 bits: CS1, high 16 bits: CS2, automatically undo the CS after operation completed* @iActiveDelay: low 16 bits: CS1, high 16 bits: CS2, delay time of read and write operation after setting CS, unit: us* @iDelayDeactive: low 16 bits: CS1, high 16 bits: CS2,, delay time of read and write operation after canceling CS, unit: us** The function return true if successful, false if fail.*/
extern bool CH347SPI_SetChipSelect(int fd, uint16_t iEnableSelect, uint16_t iChipSelect, int iIsAutoDeativeCS, int iActiveDelay, int iDelayDeactive);/*** CH347SPI_ChangeCS - SPI CS setting, must call CH347SPI_Init first* @fd: file descriptor of device* @iStatus: 0: cancel CS, 1: set CS** The function return true if successful, false if fail.*/
extern bool CH347SPI_ChangeCS(int fd, uint8_t iStatus);/*** CH347SPI_Write - write SPI data* @fd: file descriptor of device* @ignoreCS: ignore SPI chip select while true, else auto set CS* @iChipSelect: SPI chip select, ignore while BIT7 is 0, valid while BIT7 is 1* @iLength: length to write* @iWriteStep: per write length* @ioBuffer: pointer to write buffer** The function return true if successful, false if fail.*/
extern bool CH347SPI_Write(int fd, bool ignoreCS, int iChipSelect, int iLength, int iWriteStep, void *ioBuffer);/*** CH347SPI_Read - read SPI data* @fd: file descriptor of device* @ignoreCS: ignore SPI chip select while true, else auto set CS* @iChipSelect: SPI chip select, ignore while BIT7 is 0, valid while BIT7 is 1* @iLength: length to write* @oLength: pointer to read length* @ioBuffer: pointer to buffer, store data to be written from MOSI, and return data to be read from MISO** The function return true if successful, false if fail.*/
extern bool CH347SPI_Read(int fd, bool ignoreCS, int iChipSelect, int iLength, uint32_t *oLength, void *ioBuffer);/*** CH347SPI_WriteRead - write then read SPI data* @fd: file descriptor of device* @ignoreCS: ignore SPI chip select while true, else auto set CS* @iChipSelect: SPI chip select, ignore while BIT7 is 0, valid while BIT7 is 1* @iLength: data length to xfer* @ioBuffer: pointer to buffer, store data to be written from MOSI, and return data to be read from MISO** The function return true if successful, false if fail.*/
extern bool CH347SPI_WriteRead(int fd, bool ignoreCS, int iChipSelect, int iLength, void *ioBuffer);

如上API接口函数，根据不同的业务场景可以选用不同的函数。

CH347SPI_Write： 适用于单次SPI通讯长度固定，或者类似SPI FLASH有固定页/扇区大小的器件，可以提升效率。

CH347SPI_Read：适用于单次SPI通讯长度固定，或者类似SPI FLASH有固定页/扇区大小的器件，可以提升效率。

CH347SPI_WriteRead：适用于所有类型的SPI通讯，交换传输，数据从MOSI输出，同时从MISO上采集数据保存到 ioBuffer 缓冲区中。

CH347 SPI主机模式操作流程：

注：

1、CH347SPI_SetDataBits 用于启用/禁用 SPI 16位读写功能，此API为可选项。

2、CH347SPI_ChangeCS 用于手动控制芯片的 CS 片选引脚，此API为可选项。

CH347SPI_WriteRead 函数说明

ignoreCS：此次xfer传输是否忽略片选设置，true：传输开始和结束不操作片选信号，false：传输开始和结束自动使能和失能片选信号（当 iChipSelect 设定有效时）

iChipSelect：SPI 片选设置，BIT7为1，片选有效，BIT7为0，撤销片选

iLength：此次xfer数据传输的长度

ioBuffer：需要xfer传输的缓冲区，由于SPI是exchange交换传输，因此该缓冲区内容会先经过MOSI信号线对外输出，然后该API成功返回后，其内容是从MISO信号线上采集的数据。

示例：

uint8_t ioBuffer[2] = {0x11, 0x22};CH347SPI_WriteRead(fd, false, 0x80, 2, ioBuffer);

 此时，MOSI输出2个字节数据 0x11 和 0x22，然后返回 MISO数据。

图1：MISO悬空（高电平）

图2：MISO接GND（低电平）

如上为CH347的SPI功能使用说明，其他平台上Linux和Android系统上接口函数均保持类似，可直接参考移植。

 （4）应用编程—SPI 从机模式 API介绍

/*** CH347OpenDevice - open device* @pathname: device path in /dev directory** The function return positive file descriptor if successful, others if fail.*/
extern int CH347OpenDevice(const char *pathname);/*** CH347CloseDevice - close device* @fd: file descriptor of device** The function return true if successful, false if fail.*/
extern bool CH347CloseDevice(int fd);/*** CH347SPI_Init - SPI interface initialization* @fd: file descriptor of device* @SpiCfg: pointer to SPI configuration, SPI frequency could be set by SpiCfg->iClock or CH347SPI_SetFrequency API, the latter is preferred** The function return true if successful, false if fail.*/
extern bool CH347SPI_Init(int fd, mSpiCfgS *SpiCfg);/*** CH347SPI_Slave_Control - switch of reading SPI data from master * @fd: file descriptor of device* @enable: true: start reading continuously, false: stop reading** The function return true if successful, false if fail.*/
extern bool CH347SPI_Slave_Control(int fd, bool enable);/*** CH347SPI_Slave_QweryData - get spi data length* @fd: file descriptor of device* @oLength: pointer to read length** The function return true if successful, false if fail.*/
extern bool CH347SPI_Slave_QweryData(int fd, uint32_t *oLength);/*** CH347SPI_Slave_FIFOReset - reset spi data fifo* @fd: file descriptor of device** The function return true if successful, false if fail.*/
extern bool CH347SPI_Slave_FIFOReset(int fd);/*** CH347SPI_Slave_ReadData - read spi data in slave mode* @fd: file descriptor of device* @oReadBuffer: pointer to read buffer* @oReadLength: pointer to read length** The function return true if successful, false if fail.*/
extern bool CH347SPI_Slave_ReadData(int fd, void *oReadBuffer, uint32_t *oReadLength);

CH347SPI_Slave_Control： 将芯片的SPI接口切换到从机接收模式，并且驱动程序也会进入专用的从机接收模式，此时对于芯片的设置和其他功能均无法使用，直至再次调用此接口关闭从机接收模式。

CH347SPI_Slave_QweryData：查询从机模式SPI接口接收的数据总量。

CH347SPI_Slave_FIFOReset：复位SPI从机FIFO缓冲区

CH347SPI_Slave_ReadData：从SPI从机的FIFO缓冲区取出数据

CH347 SPI从机模式操作流程：

示例：

bool CH347_SPI_Slave_Init()
{bool ret;mSpiCfgS SpiCfg = { 0 };/* set spi interface in spi slave mode, [mode3] & [MSB] & output [0xFF] by default */SpiCfg.iByteOrder = 1;SpiCfg.iSpiOutDefaultData = 0xFF;SpiCfg.iMode = 0x83;/* init spi interface */ret = CH347SPI_Init(ch347device.fd, &SpiCfg);if (!ret) {printf("Failed to init SPI interface.\n");return false;} else {printf("SPI init slave ok.\n");}return true;
}void ch34x_demo_spi_slave_operate(bool enable)
{bool ret = false;uint8_t oBuffer[SPI_SLAVE_MAX_LENGTH];uint32_t oLength;int i;if (enable) {ret = CH347_SPI_Slave_Init();if (ret == false) {printf("Failed to init CH347 SPI interface.\n");return;}printf("CH347 SPI interface init succeed.\n");ret = CH347SPI_Slave_FIFOReset(ch347device.fd);if (ret == false) {printf("Failed to reset SPI slave fifo.\n");return;}printf("CH347 SPI slave fifo reset succeed.\n");ret = CH347SPI_Slave_Control(ch347device.fd, true);if (!ret)return;printf("Begin read data in slave mode.\n");while (1) {ret = CH347SPI_Slave_QweryData(ch347device.fd, &oLength);if (!ret) {printf("CH347SPI_Slave_QweryData failed.\n");goto exit;}if (oLength == 0) {usleep(10 * 1000);continue;}ret = CH347SPI_Slave_ReadData(ch347device.fd, oBuffer, &oLength);if (!ret) {printf("CH347SPI_Slave_ReadData failed.\n");goto exit;}printf("\nRead Slave data, len: %d, contents:\n", oLength);for (i = 0; i < oLength; i++) {printf("%02x ", oBuffer[i]);if (((i + 1) % 20) == 0)putchar(20);}putchar(20);}} elseret = CH347SPI_Slave_Control(ch347device.fd, false);return;exit:CH347SPI_Slave_Control(ch347device.fd, false);
}