[参考译文] MSP430F5638：让 MSP430 SPI 4引脚运行、3引脚100%解码

// setup MSP430F5638 P8 UCB1 SPI
// 4 pin master tx mode
//      nothing works, no decode at all
// 3 pin master tx mode
//      tried with & without STE used as GPIO CS
//      properly decodes about 2 out of 10 attempts
//      the 2 that work each capture up to 3500 characters correctly for 10 ms @ 500 MHz LA
//      8 fails get ASCII gibberish for all characters
// uses polling, according to TI tech support, for high speed SPI, ISR's are slower, don't use them
// P8 Tx string = "ABCDEFGH" to scope or LA, same results for both instruments
void SPI_2_M_init(void)
{
    UCB1CTL1 = 0x01;         // disable UCB1 during configuration

    // 4 pin SPI synch - no pulses at all
    // MSP430 does not work in 4 pin mode to LA's anyway
    // set all SPI-2 serial parameters
    // high nibble 1110 = clock phase = 1, polarity = 1, MSB first = 1, 8-bit = 0
    // low nibble 1101 = Master = 1, 4 pin STE low = 10, Synch Mode = 1
    // 7654 3210
    // 1110 1101 = 0xED
//    UCB1CTL0 = 0xED;

    // 4 pin SPI asynch - no pulses at all
    // try asynchronous - still not triggering LA1010
    // 7654 3210
    // 1110 1100 = 0xEC
//    UCB1CTL0 = 0xEC;

    // 3 pin SPI mode - trigger on Ch1 CLK - decodes 2 of 10 attempts
    // trigger on CS low does nothing, no decode at all
    // works 3 pin mode - CLK, MOSI pulses, MISO high, but no STE pulses
    // MSP430 only seems to like 3 pin mode
    // try 3 pin, sync - this triggers the LA1010 & U3Pro16
    // 1110
    // clock phase = 1, polarity = 1, MSB first = 1, 8-bit = 0
    // 1001
    // Master = 1, 3-pin SPI = 00, synchronous mode = 1
    // 7654 3210
    // 1110 1001 = 0xE9
    UCB1CTL0 = 0xE9;        // tried asynch 0xE8, no difference
    // try CPHA = 0
    // 7654 3210
    // 0110 1001 = 0x69
//    UCB1CTL0 = 0x69;        // never gets ABCD...

    // 7654 3210
    // 1000 0001 = 0x81
    // SMCLK = 10, Don't care xxxxx, software reset = 1
    UCB1CTL1 = 0x81;

    // BRW = divisor
    // tested BRW = 2 to 64, must be >= 6 when using X2 @ 24 MHz MSP430 clock
    UCB1BRW = 7;                      // X2 = 20 MHz / 7 = ~3 MHz (must be >= 6 to work)

    UCB1CTL1 &= ~0x01;       // enable UCB1 for use after configuration
}

// 8/27/24 - M Tx 3 pin, use GPIO to set / clear CS
// Master Tx
// uses polling
// SPI-2 uses P8 UCB1
// str = transmitted string
void setup_430_P8_SPI_2_M_TX(unsigned char *str)
{
    int i=0, length;
    length = strlen(str);

    // set alternate function for P8.4, P8.5, P8.6 - UCB1 SPI-2
    // leave P8.1 UCB1STE as GPIO to set / clear CS
    // 7654 3210
    // 0111 0000 = 0x70
    P8SEL |= 0x70;          // set for 3 pin mode
    // 7654 3210
    // 0111 0010 = 0x72
//    P8SEL |= 0x72;        // set for 4 pin mode

    // set UCB1STE P8.1 for GPIO CS
    P8DIR |= BIT1;      // set UCB1STE to out, don't need, default
    P8OUT |= BIT1;      // set UCB1STE high

    // loop continuously
    // STE CS set high by default
    while(1)
    {
        P8OUT |= BIT1;      // set UCB1STE CS high
        // Tx the string
        for (i = 0; i < length; i++)
        {
            P8OUT &= ~BIT1;     // clear UCB1STE CS low to trigger on
            while(!(UCB1IFG & UCTXIFG))     // wait for transmit buffer empty
                ;
            UCB1TXBUF = str[i];       // transmit a character
            //delayMs(10);
        }
        P8OUT |= BIT1;      // set UCB1STE CS high
    }
}