TI中文支持网SPI主机信号是这样的：Fss引脚会在CLK前一位拉低，会在CLK结束后几位前变为高电平，CLK会在DATA结束后持续一段时间（不满8位）
我用TM4C作为SPI的从机，用SSI中断的方式接收数据，进入中断后，通过判断BSY位，反复SSIDataGetNonBlocking，知道BSY复位后退出中断
感觉CLK信号最后有个小尾巴的时候，中断总是两帧数据才会退出一次。
像这种情况，信号长度（数据帧的长度）未知的情况下，用SPI从机中断的方式怎么接收数据啊？
有没有类似的，谢谢了！
Aiqing Wang：
回复 xyz549040622:
能否提供一份TM4C129X 的 SPI从设备模式（slave spi mode）的代码，谢谢！
xyz549040622：
回复 Aiqing Wang:
开的是主从的回环模式
//***************************************************************************** // // master_slave_loopback.c - Example demonstrating a simple I2C message //transmission and reception. // // Copyright (c) 2010-2014 Texas Instruments Incorporated.All rights reserved. // Software License Agreement ////Redistribution and use in source and binary forms, with or without //modification, are permitted provided that the following conditions //are met: ////Redistributions of source code must retain the above copyright //notice, this list of conditions and the following disclaimer. ////Redistributions in binary form must reproduce the above copyright //notice, this list of conditions and the following disclaimer in the //documentation and/or other materials provided with the//distribution. ////Neither the name of Texas Instruments Incorporated nor the names of //its contributors may be used to endorse or promote products derived //from this software without specific prior written permission. //// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. //// This is part of revision 2.1.0.12573 of the Tiva Firmware Development Package. // //*****************************************************************************#include <stdbool.h> #include <stdint.h> #include "inc/hw_i2c.h" #include "inc/hw_memmap.h" #include "inc/hw_types.h" #include "driverlib/gpio.h" #include "driverlib/i2c.h" #include "driverlib/pin_map.h" #include "driverlib/sysctl.h" #include "driverlib/uart.h" #include "utils/uartstdio.h"//***************************************************************************** // //! \addtogroup i2c_examples_list //! <h1>I2C Master Loopback (i2c_master_slave_loopback)</h1> //! //! This example shows how to configure the I2C0 module for loopback mode. //! This includes setting up the master and slave module.Loopback mode //! internally connects the master and slave data and clock lines together. //! The address of the slave module is set in order to read data from the //! master.Then the data is checked to make sure the received data matches //! the data that was transmitted.This example uses a polling method for //! sending and receiving data. //! //! This example uses the following peripherals and I/O signals.You must //! review these and change as needed for your own board: //! - I2C0 peripheral //! - GPIO Port B peripheral (for I2C0 pins) //! - I2C0SCL - PB2 //! - I2C0SDA - PB3 //! //! The following UART signals are configured only for displaying console //! messages for this example.These are not required for operation of I2C. //! - UART0 peripheral //! - GPIO Port A peripheral (for UART0 pins) //! - UART0RX - PA0 //! - UART0TX - PA1 //! //! This example uses the following interrupt handlers.To use this example //! in your own application you must add these interrupt handlers to your //! vector table. //! - None. // //*****************************************************************************//***************************************************************************** // // Number of I2C data packets to send. // //***************************************************************************** #define NUM_I2C_DATA 3//***************************************************************************** // // Set the address for slave module. This is a 7-bit address sent in the // following format: //[A6:A5:A4:A3:A2:A1:A0:RS] // // A zero in the "RS" position of the first byte means that the master // transmits (sends) data to the selected slave, and a one in this position // means that the master receives data from the slave. // //***************************************************************************** #define SLAVE_ADDRESS 0x3C//***************************************************************************** // // This function sets up UART0 to be used for a console to display information // as the example is running. // //***************************************************************************** void InitConsole(void) {//// Enable GPIO port A which is used for UART0 pins.// TODO: change this to whichever GPIO port you are using.//SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);//// Configure the pin muxing for UART0 functions on port A0 and A1.// This step is not necessary if your part does not support pin muxing.// TODO: change this to select the port/pin you are using.//GPIOPinConfigure(GPIO_PA0_U0RX);GPIOPinConfigure(GPIO_PA1_U0TX);//// Enable UART0 so that we can configure the clock.//SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);//// Use the internal 16MHz oscillator as the UART clock source.//UARTClockSourceSet(UART0_BASE, UART_CLOCK_PIOSC);//// Select the alternate (UART) function for these pins.// TODO: change this to select the port/pin you are using.//GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);//// Initialize the UART for console I/O.//UARTStdioConfig(0, 115200, 16000000); }//***************************************************************************** // // Configure the I2C0 master and slave and connect them using loopback mode. // //***************************************************************************** int main(void) {uint32_t pui32DataTx[NUM_I2C_DATA];uint32_t pui32DataRx[NUM_I2C_DATA];uint32_t ui32Index;//// Set the clocking to run directly from the external crystal/oscillator.// TODO: The SYSCTL_XTAL_ value must be changed to match the value of the// crystal on your board.//SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |SYSCTL_XTAL_16MHZ);//// The I2C0 peripheral must be enabled before use.//SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C0);//// For this example I2C0 is used with PortB[3:2].The actual port and// pins used may be different on your part, consult the data sheet for// more information.GPIO port B needs to be enabled so these pins can// be used.// TODO: change this to whichever GPIO port you are using.//SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);//// Configure the pin muxing for I2C0 functions on port B2 and B3.// This step is not necessary if your part does not support pin muxing.// TODO: change this to select the port/pin you are using.//GPIOPinConfigure(GPIO_PB2_I2C0SCL);GPIOPinConfigure(GPIO_PB3_I2C0SDA);//// Select the I2C function for these pins.This function will also// configure the GPIO pins pins for I2C operation, setting them to// open-drain operation with weak pull-ups.Consult the data sheet// to see which functions are allocated per pin.// TODO: change this to select the port/pin you are using.//GPIOPinTypeI2CSCL(GPIO_PORTB_BASE, GPIO_PIN_2);GPIOPinTypeI2C(GPIO_PORTB_BASE, GPIO_PIN_3);//// Enable loopback mode.Loopback mode is a built in feature that is// useful for debugging I2C operations.It internally connects the I2C// master and slave terminals, which effectively let's you send data as// a master and receive data as a slave.// NOTE: For external I2C operation you will need to use external pullups// that are stronger than the internal pullups.Refer to the datasheet for// more information.//HWREG(I2C0_BASE + I2C_O_MCR) |= 0x01;//// Enable and initialize the I2C0 master module.Use the system clock for// the I2C0 module.The last parameter sets the I2C data transfer rate.// If false the data rate is set to 100kbps and if true the data rate will// be set to 400kbps.For this example we will use a data rate of 100kbps.//I2CMasterInitExpClk(I2C0_BASE, SysCtlClockGet(), false);//// Enable the I2C0 slave module. This module is enabled only for testing// purposes.It does not need to be enabled for proper operation of the// I2Cx master module.//I2CSlaveEnable(I2C0_BASE);//// Set the slave address to SLAVE_ADDRESS.In loopback mode, it's an// arbitrary 7-bit number (set in a macro above) that is sent to the// I2CMasterSlaveAddrSet function.//I2CSlaveInit(I2C0_BASE, SLAVE_ADDRESS);//// Tell the master module what address it will place on the bus when// communicating with the slave.Set the address to SLAVE_ADDRESS// (as set in the slave module).The receive parameter is set to false// which indicates the I2C Master is initiating a writes to the slave.If// true, that would indicate that the I2C Master is initiating reads from// the slave.//I2CMasterSlaveAddrSet(I2C0_BASE, SLAVE_ADDRESS, false);//// Set up the serial console to use for displaying messages.This is// just for this example program and is not needed for I2C operation.//InitConsole();//// Display the example setup on the console.//UARTprintf("I2C Loopback Example ->");UARTprintf("\nModule = I2C0");UARTprintf("\nMode = Single Send/Receive");UARTprintf("\nRate = 100kbps\n\n");//// Initalize the data to send.//pui32DataTx[0] = 'I';pui32DataTx[1] = '2';pui32DataTx[2] = 'C';//// Initalize the receive buffer.//for(ui32Index = 0; ui32Index < NUM_I2C_DATA; ui32Index++){pui32DataRx[ui32Index] = 0;}//// Indicate the direction of the data.//UARTprintf("Tranferring from: Master -> Slave\n");//// Send 3 peices of I2C data from the master to the slave.//for(ui32Index = 0; ui32Index < NUM_I2C_DATA; ui32Index++){//// Display the data that the I2C0 master is transferring.//UARTprintf("Sending: '%c'. . .", pui32DataTx[ui32Index]);//// Place the data to be sent in the data register//I2CMasterDataPut(I2C0_BASE, pui32DataTx[ui32Index]);//// Initiate send of data from the master.Since the loopback// mode is enabled, the master and slave units are connected// allowing us to receive the same data that we sent out.//I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_SEND);//// Wait until the slave has received and acknowledged the data.//while(!(I2CSlaveStatus(I2C0_BASE) & I2C_SLAVE_ACT_RREQ)){}//// Read the data from the slave.//pui32DataRx[ui32Index] = I2CSlaveDataGet(I2C0_BASE);//// Wait until master module is done transferring.//while(I2CMasterBusy(I2C0_BASE)){}//// Display the data that the slave has received.//UARTprintf("Received: '%c'\n", pui32DataRx[ui32Index]);}//// Reset receive buffer.//for(ui32Index = 0; ui32Index < NUM_I2C_DATA; ui32Index++){pui32DataRx[ui32Index] = 0;}//// Indicate the direction of the data.//UARTprintf("\n\nTranferring from: Slave -> Master\n");//// Modifiy the data direction to true, so that seeing the address will// indicate that the I2C Master is initiating a read from the slave.//I2CMasterSlaveAddrSet(I2C0_BASE, SLAVE_ADDRESS, true);//// Do a dummy receive to make sure you don't get junk on the first receive.//I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_RECEIVE);//// Dummy acknowledge and wait for the receive request from the master.// This is done to clear any flags that should not be set.//while(!(I2CSlaveStatus(I2C0_BASE) & I2C_SLAVE_ACT_TREQ)){}for(ui32Index = 0; ui32Index < NUM_I2C_DATA; ui32Index++){//// Display the data that I2C0 slave module is transferring.//UARTprintf("Sending: '%c'. . .", pui32DataTx[ui32Index]);//// Place the data to be sent in the data register//I2CSlaveDataPut(I2C0_BASE, pui32DataTx[ui32Index]);//// Tell the master to read data.//I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_SINGLE_RECEIVE);//// Wait until the slave is done sending data.//while(!(I2CSlaveStatus(I2C0_BASE) & I2C_SLAVE_ACT_TREQ)){}//// Read the data from the master.//pui32DataRx[ui32Index] = I2CMasterDataGet(I2C0_BASE);//// Display the data that the slave has received.//UARTprintf("Received: '%c'\n", pui32DataRx[ui32Index]);}//// Tell the user that the test is done.//UARTprintf("\nDone.\n\n");//// Return no errors//return(0); }
