CCS/MSP430G2553: USCI(SPI) Interrupt and Timer interrupt

Hello Qibin,

It sounds like you are displaying your data via a command terminal on PC after sending it over. If that is the case, then you need to translate your data to ASCII characters before being displayed. the program to do this could be on either device, it just needs to be done before you send it to your PC.

Hi Jace,
Thank you for replying. Yes, I have translated the float value to strings and the values like RATE: 004.3000 VALUE: 000.1554 are the data exactly what I need, but late it turns out like disaster. I was wondering how can I make the communication correctly with each single character right, and I have no idea about how long delay time should be, the delay time between transmitting of two single byte.
And if there is someone came up with such kind of problems before, could you please share me.

best regards,
Qibin

And also, I have try out SPI communication between MSP430g2553 and CC430f6137(master), both side I used USCI ISR, without time interrupt

and the communcation runs very good with nice string infomation transmission.

Here are some code of slave MSP430g2553, in main() just initialized the setting, the USCI(SPI) ISR do part of tranmission FSM, and I think the conflict between USCI ISR and timer ISR is the key of the problem, I have not so much experience with that, and I am still searching a solution.

int main(void)
{
    WDTCTL = WDTPW | WDTHOLD;	// Stop watchdog timer

    init_SMS50();  // init clk,comparator, coresponding PINs
    init_clk();
    initSPI();

    __bis_SR_register(GIE);

    while(1)
	{
    	__no_operation();
	}
}

// cycle counter
#pragma vector=TIMER0_A0_VECTOR
__interrupt void Timer0_A0_Compare(void)
{	TA0CCTL0 &= ~CCIFG; //clear interrupt flag

	 comp_out = BIT0 & CACTL2;  // catch comparator output
	 P2OUT = BIT0 & (~comp_out);  // inverte P2.0 as ~Q
	 NOC ++;  // increment NOC
	 if(comp_out)	NO1++;  //incrment NO1 if Q:HIGH

	 if( NOC == MEASURE_CYCLES)
	 {
		ratio = (float) 100*NO1/NOC;  // save ratio in buffer [%]
		NOC = 0;
		NO1 = 0;
	 }
}


#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCIA0RX_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCIAB0RX_VECTOR))) USCI0RX_ISR (void)
#else
#error Compiler not supported!
#endif
{
	uca0_rx_val = UCA0RXBUF;
	switch(SlaveMode)
	{
		case RX_REG_ADDRESS_MODE:		//prapare for tranmission
			TransmitIndex = 0;
			if(uca0_rx_val == MOISTURE_RATE)
			{
				TXByteCtr  = RATE_LENGTH;
				CopyArray(RATE,TransmitBuffer,RATE_LENGTH);
			}
			else if(uca0_rx_val == MOISTURE_VALUE)
			{
				TXByteCtr  = VALUE_LENGTH;
				CopyArray(VALUE,TransmitBuffer,VALUE_LENGTH);
			}
			SendUCA0Data(TransmitBuffer[TransmitIndex++]);	//transmit first byte
			TXByteCtr--;
			SlaveMode = TX_DATA_MODE;
			break;
		case TX_DATA_MODE:
			if(TXByteCtr > 0)
			{
				SendUCA0Data(TransmitBuffer[TransmitIndex++]);
				TXByteCtr--;
			}
			if(TXByteCtr == 0)
			{
				SlaveMode = IDLE_MODE;
			}
			break;
		case IDLE_MODE:
			SlaveMode = RX_REG_ADDRESS_MODE;
			break;
		default:break;
	}

}

Hi Bruce,
I took you advice, added "else break;" after if()/elseif(), and now the strange strings never showed up.
As you mentioned of " P2OUT = BIT0& (~comp_out);", I need the first byte of register CACTL2, which is the output of comparator, and I need to PIN2.0 be convetered of comparator output and use this a feed back of the circuit.
Thank you for your advice, very helpful.