I am trying to create working SPI code for the MSP430G2121. I am referencing the example code provided by TI and using a logic analyzer to read the values on the MOSI and MISO lines. However, when I flash the code, the MOSI and MISO values are constantly 0x00 and 0xFF respectively.
Is there something I am missing in the setup?
/* --COPYRIGHT--,BSD_EX * Copyright (c) 2012, Texas Instruments Incorporated * All rights reserved. * * 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. * ******************************************************************************* * * MSP430 CODE EXAMPLE DISCLAIMER * * MSP430 code examples are self-contained low-level programs that typically * demonstrate a single peripheral function or device feature in a highly * concise manner. For this the code may rely on the device's power-on default * register values and settings such as the clock configuration and care must * be taken when combining code from several examples to avoid potential side * effects. Also see www.ti.com/grace for a GUI- and www.ti.com/msp430ware * for an API functional library-approach to peripheral configuration. * * --/COPYRIGHT--*/ //****************************************************************************** // MSP430G2x21/G2x31 Demo - SPI full-Duplex 3-wire Master // // Description: SPI Master communicates full-duplex with SPI Slave using // 3-wire mode. The level on P1.4 is TX'ed and RX'ed to P1.0. // Master will pulse slave reset for synch start. // ACLK = n/a, MCLK = SMCLK = Default DCO // // **** used with "msp430g2x21_usi_03.c" **** // // Slave Master // MSP430G2x21/G2x31 MSP430G2x21/G2x31 // ----------------- ----------------- // | XIN|- /|\| XIN|- // | | | | | // | XOUT|- --|RST XOUT|- // | | /|\ | | // | RST/NMI|--+<----|P1.2 | // LED <-|P1.0 | | P1.4|<- // ->|P1.4 | | P1.0|-> LED // | SDI/P1.7|<-------|P1.6/SDO | // | SDO/P1.6|------->|P1.7/SDI | // | SCLK/P1.5|<-------|P1.5/SCLK | // // D. Dang // Texas Instruments Inc. // October 2010 // Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10 //****************************************************************************** #include <msp430.h> int main(void) { volatile unsigned int i; WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer P1OUT = 0x10; // P1.4 set, else reset P1REN |= 0x10; // P1.4 pullup P1DIR = 0x01; // P1.0 output, else input USICTL0 |= USIPE7 + USIPE6 + USIPE5 + USIMST + USIOE; // Port, SPI master USICTL1 |= USIIE; // Counter interrupt, flag remains set USICKCTL = USIDIV_4 + USISSEL_2; // /16 SMCLK USICTL0 &= ~USISWRST; // USI released for operation USISRL = P1IN; // init-load data P1DIR |= 0x04; // Reset Slave P1DIR &= ~0x04; for (i = 0xFFF; i > 0; i--); // Time for slave to ready USICNT = 8; // init-load counter __bis_SR_register(LPM0_bits + GIE); // Enter LPM0 w/ interrupt } // USI interrupt service routine #if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__) #pragma vector=USI_VECTOR __interrupt void universal_serial_interface(void) #elif defined(__GNUC__) void __attribute__ ((interrupt(USI_VECTOR))) universal_serial_interface (void) #else #error Compiler not supported! #endif { if (0x10 & USISRL) P1OUT |= 0x01; else P1OUT &= ~0x01; USISRL = P1IN; USICNT = 8; // re-load counter }