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MSP430G2553: I2C USCI Example code to add serial output

Part Number: MSP430G2553
Other Parts Discussed in Thread: ENERGIA, MSP430WARE

I am using a MSP-430G2553 as a master to read values from a sensor, programming in Energia. The data on my scope looks good but I want to output it to a Serial.println. 

When i add the Serial.begin(9600) I get the following error.  "core.a(usci_isr_handler.c.o): In function `__isr_6':"

Could someone tell me how to implement a serial monitor in this example?

  • Hi Patrick,

    Are you using the following example code "master_reader"?

    // Wire Master Reader
    // by Nicholas Zambetti <http://www.zambetti.com>
    
    // Demonstrates use of the Wire library
    // Reads data from an I2C/TWI slave device
    // Refer to the "Wire Slave Sender" example for use with this
    
    // Created 29 March 2006
    
    // This example code is in the public domain.
    
    
    #include <Wire.h>
    
    void setup()
    {
      Wire.begin();        // join i2c bus (address optional for master)
      Serial.begin(9600);  // start serial for output
    }
    
    void loop()
    {
      Wire.requestFrom(2, 6);    // request 6 bytes from slave device #2
    
      while(Wire.available())    // slave may send less than requested
      { 
        char c = Wire.read(); // receive a byte as character
        Serial.print(c);         // print the character
      }
    
      delay(500);
    }

    Regards,

    James

    MSP Customer Applications

  • Hello,

    This is the code I am referring too. Appreciate the help.

    /* --COPYRIGHT--,BSD_EX
    * Copyright (c) 2012, Texas Instruments Incorporated
    * All rights reserved.
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    *
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    * 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--*/
    //******************************************************************************
    // MSP430G2xx3 Demo - USCI_B0 I2C Master TX/RX multiple bytes from MSP430 Slave
    // with a repeated start in between TX and RX operations.
    //
    // Description: This demo connects two MSP430's via the I2C bus. The master
    // transmits to the slave, then a repeated start is generated followed by a
    // receive operation. This is the master code. This code demonstrates how to
    // implement an I2C repeated start with the USCI module using the USCI_B0 TX
    // interrupt.
    // ACLK = n/a, MCLK = SMCLK = BRCLK = default DCO = ~1.2MHz
    //
    // ***to be used with msp430x22x4_uscib0_i2c_13.c***
    //
    // /|\ /|\
    // MSP430F24x 10k 10k MSP430G2xx3
    // slave | | master
    // ----------------- | | -----------------
    // -|XIN P3.1/UCB0SDA|<-|---+->|P3.1/UCB0SDA XIN|-
    // | | | | |
    // -|XOUT | | | XOUT|-
    // | P3.2/UCB0SCL|<-+----->|P3.2/UCB0SCL |
    // | | | |
    //
    // D. Dang
    // Texas Instruments Inc.
    // February 2011
    // Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10
    //******************************************************************************
    #include <msp430.h>

    #define NUM_BYTES_TX 3 // How many bytes?
    #define NUM_BYTES_RX 2

    int RXByteCtr, RPT_Flag = 0; // enables repeated start when 1
    volatile unsigned char RxBuffer[128]; // Allocate 128 byte of RAM
    unsigned char *PTxData; // Pointer to TX data
    unsigned char *PRxData; // Pointer to RX data
    unsigned char TXByteCtr, RX = 0;
    unsigned char MSData = 0x00;

    void Setup_TX(void);
    void Setup_RX(void);
    void Transmit(void);
    void Receive(void);
    void Debug(void);
    int main(void)
    {
    WDTCTL = WDTPW + WDTHOLD; // Stop WDT
    P1SEL |= BIT6 + BIT7; // Assign I2C pins to USCI_B0
    P1SEL2|= BIT6 + BIT7; // Assign I2C pins to USCI_B0

    while(1){

    //Transmit process
    Setup_TX();
    RPT_Flag = 1;
    Transmit();
    while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent

    //Receive process
    Setup_RX();
    Receive();

    while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
    }
    }

    //-------------------------------------------------------------------------------
    // The USCI_B0 data ISR is used to move received data from the I2C slave
    // to the MSP430 memory. It is structured such that it can be used to receive
    // any 2+ number of bytes by pre-loading RXByteCtr with the byte count.
    //-------------------------------------------------------------------------------
    #if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
    #pragma vector = USCIAB0TX_VECTOR
    __interrupt void USCIAB0TX_ISR(void)
    #elif defined(__GNUC__)
    void __attribute__ ((interrupt(USCIAB0TX_VECTOR))) USCIAB0TX_ISR (void)
    #else
    #error Compiler not supported!
    #endif
    {
    if(RX == 1){ // Master Recieve?
    RXByteCtr--; // Decrement RX byte counter
    if (RXByteCtr)
    {
    *PRxData++ = UCB0RXBUF; // Move RX data to address PRxData
    }
    else
    {
    if(RPT_Flag == 0)
    UCB0CTL1 |= UCTXSTP; // No Repeated Start: stop condition
    if(RPT_Flag == 1){ // if Repeated Start: do nothing
    RPT_Flag = 0;
    }
    *PRxData = UCB0RXBUF; // Move final RX data to PRxData
    __bic_SR_register_on_exit(CPUOFF); // Exit LPM0
    }
    }

    else{ // Master Transmit
    if (TXByteCtr) // Check TX byte counter
    {
    UCB0TXBUF = MSData++; // Load TX buffer
    TXByteCtr--; // Decrement TX byte counter
    }
    else
    {
    if(RPT_Flag == 1){
    RPT_Flag = 0;
    PTxData = &MSData; // TX array start address
    TXByteCtr = NUM_BYTES_TX; // Load TX byte counter
    __bic_SR_register_on_exit(CPUOFF);
    }
    else{
    UCB0CTL1 |= UCTXSTP; // I2C stop condition
    IFG2 &= ~UCB0TXIFG; // Clear USCI_B0 TX int flag
    __bic_SR_register_on_exit(CPUOFF); // Exit LPM0
    }
    }
    }

    }

    void Setup_TX(void){
    __disable_interrupt();
    RX = 0;
    IE2 &= ~UCB0RXIE;
    while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent// Disable RX interrupt
    UCB0CTL1 |= UCSWRST; // Enable SW reset
    UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
    UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
    UCB0BR0 = 12; // fSCL = SMCLK/12 = ~100kHz
    UCB0BR1 = 0;
    UCB0I2CSA = 0x48; // Slave Address is 048h
    UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
    IE2 |= UCB0TXIE; // Enable TX interrupt
    }
    void Setup_RX(void){
    __disable_interrupt();
    RX = 1;
    IE2 &= ~UCB0TXIE;
    UCB0CTL1 |= UCSWRST; // Enable SW reset
    UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
    UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
    UCB0BR0 = 12; // fSCL = SMCLK/12 = ~100kHz
    UCB0BR1 = 0;
    UCB0I2CSA = 0x48; // Slave Address is 048h
    UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
    IE2 |= UCB0RXIE; // Enable RX interrupt
    }
    void Transmit(void){
    PTxData = &MSData; // TX array start address
    TXByteCtr = NUM_BYTES_TX; // Load TX byte counter
    while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
    UCB0CTL1 |= UCTR + UCTXSTT; // I2C TX, start condition
    //__bis_SR_register(CPUOFF + GIE); // Enter LPM0 w/ interrupts
    }
    void Receive(void){
    PRxData = (unsigned char *)RxBuffer; // Start of RX buffer
    RXByteCtr = NUM_BYTES_RX-1; // Load RX byte counter
    while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
    Debug(); // Enable RX interrupt
    UCB0CTL1 |= UCTXSTT; // I2C start condition
    //__bis_SR_register(CPUOFF + GIE); // Enter LPM0 w/ interrupts
    }
    void Debug(void){
    __disable_interrupt();
    //Serial.print(*PRxData);
    IE2 |= UCB0RXIE;
    }

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