Hi I am new to this forum.
I did try my best to find an answer, but if the answer is just there please just tell me.
I CCS5.5, I chose from the one click projects (in TI resource explorer) msp430g2xx3_uscia0_spi_09 and downloaded it to the Launchpad.
here is the code of the project that is generated :
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//******************************************************************************
// MSP430G2xx3 Demo - USCI_A0, SPI 3-Wire Master Incremented Data
//
// Description: SPI master talks to SPI slave using 3-wire mode. Incrementing
// data is sent by the master starting at 0x01. Received data is expected to
// be same as the previous transmission. USCI RX ISR is used to handle
// communication with the CPU, normally in LPM0. If high, P1.0 indicates
// valid data reception.
// ACLK = n/a, MCLK = SMCLK = DCO ~1.2MHz, BRCLK = SMCLK/2
//
// Use with SPI Slave Data Echo code example. If slave is in debug mode, P3.6
// slave reset signal conflicts with slave's JTAG; to work around, use IAR's
// "Release JTAG on Go" on slave device. If breakpoints are set in
// slave RX ISR, master must stopped also to avoid overrunning slave
// RXBUF.
//
// MSP430G2xx3
// -----------------
// /|\| XIN|-
// | | |
// --|RST XOUT|-
// | |
// | P1.2|-> Data Out (UCA0SIMO)
// | |
// LED <-|P1.0 P1.1|<- Data In (UCA0SOMI)
// | |
// Slave reset <-|P1.5 P1.4|-> Serial Clock Out (UCA0CLK)
//
//
// D. Dang
// Texas Instruments Inc.
// February 2011
// Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10
//******************************************************************************
#include <msp430.h>
unsigned char MST_Data, SLV_Data;
int main(void)
{
volatile unsigned int i;
WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer
P1OUT = 0x00; // P1 setup for LED & reset output
P1DIR |= BIT0 + BIT5; //
P1SEL = BIT1 + BIT2 + BIT4;
P1SEL2 = BIT1 + BIT2 + BIT4;
UCA0CTL0 |= UCCKPL + UCMSB + UCMST + UCSYNC; // 3-pin, 8-bit SPI master
UCA0CTL1 |= UCSSEL_2; // SMCLK
UCA0BR0 |= 0x02; // /2
UCA0BR1 = 0; //
UCA0MCTL = 0; // No modulation
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
IE2 |= UCA0RXIE; // Enable USCI0 RX interrupt
P1OUT &= ~BIT5; // Now with SPI signals initialized,
P1OUT |= BIT5; // reset slave
__delay_cycles(75); // Wait for slave to initialize
MST_Data = 0x01; // Initialize data values
SLV_Data = 0x00;
UCA0TXBUF = MST_Data; // Transmit first character
__bis_SR_register(LPM0_bits + GIE); // CPU off, enable interrupts
}
// Test for valid RX and TX character
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCIA0RX_ISR(void)
{
volatile unsigned int i;
while (!(IFG2 & UCA0TXIFG)); // USCI_A0 TX buffer ready?
if (UCA0RXBUF == SLV_Data) // Test for correct character RX'd
P1OUT |= BIT0; // If correct, light LED
else
P1OUT &= ~BIT0; // If incorrect, clear LED
MST_Data++; // Increment master value
SLV_Data++; // Increment expected slave value
UCA0TXBUF = MST_Data; // Send next value
__delay_cycles(50); // Add time between transmissions to
} // make sure slave can keep up
Here is my problem :
Right now the launchpad is not wired to any other device, and still the red LED indicating that a valid response was received is is blinking rapidly. It seems strange that the interrupt is even reached, if nothing is connected.
Morever the red light indicated that a valid echo has been received, how is that possible ?
I'm trying to learn SPI through experimenting with the launchpad can anyone direct me.
Thanks in advance.
