I'm trying to control a RTC M41T94 via SPI with a MSP430F2274 microcontroller, but I cannot set the internal registers of this component. I've made a more complete code, but, for testing, I'm using the code below:
#include "msp430f2274.h"
void Iniciar();
void SetRTC(char byte, int endereco);
char GetRTC(int endereco);
void main(){
WDTCTL = WDTPW + WDTHOLD;
unsigned char valor = 0;
P1DIR = 0x30; //LEDs
P1OUT = 0x30;
Iniciar();
__delay_cycles(250);
SetRTC(0x11,0x09);
while(1){
__delay_cycles(250);
valor = GetRTC(0x09);
}
}
void Iniciar(){
P4SEL &= ~(0x02);
P4OUT |= 0x02;//Seta o SS de forma que passe a estar em low.
P4DIR |= 0x02;
UCB0CTL1 |= UCSWRST; //Desativa SPI
UCB0CTL0 = UCCKPL + UCMSB + UCMST + UCSYNC + UCMODE_0; //sincronizado, master mode, MSB como primeiro bit
UCB0CTL1 = UCSWRST + UCSSEL_2; // Use SMCLK, keep RESET
UCB0BR0 = 0x03; // Initial SPI clock must be <400kHz
UCB0BR1 = 0x00; // f_UCxCLK = 1MHz/3 = 333kHz
P3SEL |= 0x0E;//sel clk, somi, simo
P3DIR |= 0x0A;//dir clk, simo
P3REN |= 0x04;//ren somi
P3OUT |= 0x04;//out somi
UC0IFG &= ~UCB0RXIFG;
UC0IE |= UCB0TXIE+UCB0RXIE;
UCB0CTL1 &= ~UCSWRST; //Reativa SPI
}
void SetRTC(char byte, int endereco){
int gie = __get_SR_register() & GIE; //backup das interrupções atuais
__disable_interrupt();
P4OUT &= ~(0x02);//Habilita o CS
while (!(UC0IFG & UCB0TXIFG)); //delay pro TX ficar operacional
UCB0TXBUF = endereco; //Transferência do byte inicial
while (!(UC0IFG & UCB0TXIFG)); //delay pro TX ficar operacional
UCB0TXBUF = byte; //Transferência do byte
while (UCB0STAT & UCBUSY);
P4OUT |= 0x02;//desabilita o CS
__bis_SR_register(gie); //recover das interrupções
}
char GetRTC(int endereco){
char retorno;
int gie = __get_SR_register() & GIE;
__disable_interrupt();
P4OUT &= ~(0x02);//Habilita o CS
while (!(IFG2 & UCB0TXIFG));
UCB0TXBUF = (0x80 | endereco);//Para o MSB ser 1, ou seja, para a operação ser de leitura
UC0IFG &= ~UCB0RXIFG; //certeza de que o buffer de recebimento está limpo
while (!(IFG2 & UCB0RXIFG));
retorno = UCB0RXBUF;
while (UCB0STAT & UCBUSY);
P4OUT |= 0x02;//desabilita o CS
__bis_SR_register(gie); // Restore original GIE state
return retorno;
}
In my IAR workbench, there is a breakpoint in the "__delay_cycles" inside the "while". When I use the "Locals" window to watch the "valor" variable, it seems to be always 0x00 or 0xFF, never 0x11. I flash the LEDs because sometimes is hard to fix bad connections in the USB development stick. It's possible that the problem is in hardware, not in software, but I want to be sure about the software before trying something in the board.
Thank you
