[参考译文] TM4C123GH6PM：SPI 从器件的 SSIDataGet 阻塞

https://e2e.ti.com/support/microcontrollers/arm-based-microcontrollers-group/arm-based-microcontrollers/f/arm-based-microcontrollers-forum/1216291/tm4c123gh6pm-ssidataget-blocking-for-spi-slave

大家好、我正在使用一对 TM4C123G 评估板尝试使 SSI 通道正常工作。 这些电路板具有 TM4C123GH6PM 微控制器。 我正在使用最新版本的 Code Composer Studio 和 TivaWare 2.2.0.295。

在板之间、我们连接了 SSI1时钟、SSI1 RX/TX 交叉-板上1的 RX 连接到板上2的 TX、反之亦然。 我有两个 CCS 项目、一个是 SPI 主设备、另一个是 SPI 从设备。 我只是尝试以每秒两次的频率将"1234"从主设备传输到从设备。 我们看了示波器上的这些行、我们看到了一个1MHz 时钟和2Hz 数据。 从这一点来看、主侧似乎按预期工作。 我遇到的这个问题是在从器件上。 设置完成后、我进入了尝试读取数据的循环、并且对 SSIDataGet 的第一次调用从不返回。 两侧都有源代码。 "我怎么了?"

// SPI master
#include <stdint.h>
#include "inc/hw_memmap.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "driverlib/ssi.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"

/////////////////////////////////////////////////////////////////////////////
void InitializeSystem()
{
    // Set the clocking to run directly from the crystal.
    SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ);

    // Initialize UART1 to 115200 baud, N-8-1
    // UART1 : GPIO Port B : UART1RX = PB0 : UART1TX = PB1
    SysCtlPeripheralEnable(SYSCTL_PERIPH_UART1);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);

    GPIOPinConfigure(GPIO_PB0_U1RX);
    GPIOPinConfigure(GPIO_PB1_U1TX);

    GPIOPinTypeUART(GPIO_PORTB_BASE, GPIO_PIN_0 | GPIO_PIN_1);

    UARTConfigSetExpClk(UART1_BASE, SysCtlClockGet(), 115200,
                        UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE | UART_CONFIG_PAR_NONE);
}

/////////////////////////////////////////////////////////////////////////////
void InitializeSSI1()
{
    // Enable the SSI1 peripheral for use.
    SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI1);

    // We have PD0 (SSI1 Clk), PD2 (SSI1 Rx), and PD3 (SSI1 Tx) connected.
    // (Odd thing, pins/ports for SSI1 are the same as SSI3 ?!)
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);

    // Configure the pin muxing for SSI functions
    GPIOPinConfigure(GPIO_PD0_SSI1CLK);
    GPIOPinConfigure(GPIO_PD1_SSI1FSS);
    GPIOPinConfigure(GPIO_PD2_SSI1RX);
    GPIOPinConfigure(GPIO_PD3_SSI1TX);

    // Configure the GPIO settings for the SSI pins.  This function also gives
    // control of these pins to the SSI hardware.
    GPIOPinTypeSSI(GPIO_PORTD_BASE, GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_2 | GPIO_PIN_3);

    // Configure and enable the SSI port for SPI master mode.
    SSIDisable(SSI1_BASE);
    SSIConfigSetExpClk(SSI1_BASE, SysCtlClockGet(), SSI_FRF_MOTO_MODE_0, SSI_MODE_MASTER, 1000000, 8);

    // Advance mode settings. Legacy is default. I've seen several mentions
    // in technical forum discussions that when writing as SSI master, you
    // need "dummy" reads (in legacy mode)?
    //SSIAdvModeSet(SSI1_BASE, SSI_ADV_MODE_WRITE);

    // Enable the SSI module.
    SSIEnable(SSI1_BASE);

    // Read residual data from the SSI port so we don't read any junk.
    uint32_t RxData;
    while (SSIDataGetNonBlocking(SSI1_BASE, &RxData))
    {
    }
}

/////////////////////////////////////////////////////////////////////////////
int main(void)
{
    InitializeSystem();
    InitializeSSI1();

    // A call to SysCtlDelay with a delay count of 1 takes 3 clock cycles
    unsigned int nDelayOneMillisecond = (SysCtlClockGet() / 3) / 1000;
    const unsigned int nDelayCount = 500 /* milliseconds */ * nDelayOneMillisecond;

    const unsigned int Message[4] = { '1', '2', '3', '4' };
    uint32_t RxData = 0;
    while (true)
    {
        // Transmit on SPI and UART every <n> milliseconds.
        SysCtlDelay(nDelayCount);

        for (unsigned int nByte = 0 ; nByte < 4 ; nByte++)
        {
            while (SSIDataGetNonBlocking(SSI1_BASE, &RxData)) {}
            SSIDataPut(SSI1_BASE, Message[nByte]);
//            SSIDataGetNonBlocking(SSI1_BASE, &RxData);
            UARTCharPut(UART1_BASE, (unsigned char)Message[nByte]);
        }
    }
}

// SPI slave
#include <stdint.h>
#include "inc/hw_memmap.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "driverlib/ssi.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"

/////////////////////////////////////////////////////////////////////////////
void InitializeSystem()
{
    // Set the clocking to run directly from the crystal.
    SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ);

    // Initialize UART1 to 115200 baud, N-8-1
    // UART1 : GPIO Port B : UART1RX = PB0 : UART1TX = PB1
    SysCtlPeripheralEnable(SYSCTL_PERIPH_UART1);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);

    GPIOPinConfigure(GPIO_PB0_U1RX);
    GPIOPinConfigure(GPIO_PB1_U1TX);

    GPIOPinTypeUART(GPIO_PORTB_BASE, GPIO_PIN_0 | GPIO_PIN_1);

    UARTConfigSetExpClk(UART1_BASE, SysCtlClockGet(), 115200,
                        UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE | UART_CONFIG_PAR_NONE);
}

/////////////////////////////////////////////////////////////////////////////
void InitializeSSI1()
{
    // Enable the SSI1 peripheral for use.
    SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI1);

    // We have PD0 (SSI1 Clk), PD2 (SSI1 Rx), and PD3 (SSI1 Tx) connected.
    // (Odd thing, pins/ports for SSI1 are the same as SSI3 ?!)
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);

    // Configure the pin muxing for SSI functions
    GPIOPinConfigure(GPIO_PD0_SSI1CLK);
    GPIOPinConfigure(GPIO_PD1_SSI1FSS);
    GPIOPinConfigure(GPIO_PD2_SSI1RX);
    GPIOPinConfigure(GPIO_PD3_SSI1TX);

    // Configure the GPIO settings for the SSI pins.  This function also gives
    // control of these pins to the SSI hardware.
    GPIOPinTypeSSI(GPIO_PORTD_BASE, GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_2 | GPIO_PIN_3);

    // Configure and enable the SSI port for SPI slave mode.
    SSIDisable(SSI1_BASE);
    SSIConfigSetExpClk(SSI1_BASE, SysCtlClockGet(), SSI_FRF_MOTO_MODE_0, SSI_MODE_SLAVE, 1000000, 8);
    //SSIConfigSetExpClk(SSI1_BASE, SysCtlClockGet(), SSI_FRF_MOTO_MODE_0, SSI_MODE_SLAVE_OD, 1000000, 8);

    // Advance mode settings. Legacy is default.
    //SSIAdvModeSet(SSI1_BASE, SSI_ADV_MODE_LEGACY);

    // Enable the SSI module.
    SSIEnable(SSI1_BASE);

    // Read residual data from the SSI port so we don't read any junk.
    uint32_t RxData;
    while (SSIDataGetNonBlocking(SSI1_BASE, &RxData))
    {
    }
}

/////////////////////////////////////////////////////////////////////////////
int main(void)
{
    // Initialize the system
    InitializeSystem();
    InitializeSSI1();

    unsigned int nByte = 0;
    while (true)
    {
        // Get next charater on SPI and forward to UART
        SSIDataPut(SSI1_BASE, 0); // dummy write?
        SSIDataGet(SSI1_BASE, &nByte);
        UARTCharPut(UART1_BASE, (unsigned char)nByte);
    }
}