ez430-RF2500 SPI

Nikolai Kolev

Other Parts Discussed in Thread: CC2500, MSP430F1121

Hi,

I want to use SPI on ez430-rf2500 in "end device software configuration". It seems that P3.0,P3.1,P3.2,P3.3 /UCB0/ are used for serial communication with CC2500. But UCA0 - P3.4 - UCA0SIMO, P3.5 - UCAOSOMI are free on the battery board - "end device" is not communicating with PC. Is it possible to emulate clock signal for SPI or UCA0CLK with other different digital pin without polling clock output on P3.0 ant thus affecting CC2500 communication?

Regards.

N. Kolev

over 17 years ago

0 SRIHK over 17 years ago

Intellectual 975 points

I think the code below should be a help for ur requirement

//******************************************************************************
//   MSP430F22x4 Demo - USCI_A0, Ultra-Low Pwr UART 9600 String, 32kHz ACLK
//
//   Description: This program demonstrates a full-duplex 9600-baud UART using
//   USCI_A0 and a 32kHz crystal. The program will wait in LPM3, and will
//   respond to a received 'u' character using 8N1 protocol. The response will
//   be the string 'Hello World'.
//   ACLK = BRCLK = LFXT1 = 32768Hz, MCLK = SMCLK = DCO ~1.2MHz
//   Baud rate divider with 32768Hz XTAL @9600 = 32768Hz/9600 = 3.41
//   //* An external watch crystal is required on XIN XOUT for ACLK *//
//
//                MSP430F22x4
//             -----------------
//         /|\|              XIN|-
//          | |                 | 32kHz
//          --|RST          XOUT|-
//            |                 |
//            |     P3.4/UCA0TXD|------------> RX of USB emulator
//            |                 | 9600 - 8N1
//            |     P3.5/UCA0RXD|<------------ TX of USB emulator
//
//   A. Dannenberg
//   Texas Instruments Inc.
//   October 2006
//   Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.41A
//******************************************************************************
#include "msp430x22x4.h"

const char string1[] = { "Hello World\r\n" };
unsigned int i;

void main(void)
{
WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
BCSCTL1 = CALBC1_8MHZ;                    // Set DCO after random function
DCOCTL = CALDCO_8MHZ;

                    // LFXT1 = VLO

P1DIR = 0xFF;                             // All P1.x outputs
P1OUT = 0;                                // All P1.x reset
P2DIR = 0xFF;                             // All P2.x outputs
P2OUT = 0;                                // All P2.x reset
P3SEL = 0x30;                             // P3.4,5 = USCI_A0 TXD/RXD
P3DIR = 0xFF;                             // All P3.x outputs
P3OUT = 0;                                // All P3.x reset
P4DIR = 0xFF;                             // All P4.x outputs
P4OUT = 0;                                // All P4.x reset
UCA0CTL1 |= UCSSEL_2;                     // CLK = SMCLK if u want 32khz xtal then select UCSSEL_1 in UCA0CTL1 with br0=3, br1=0 decimal values
UCA0BR0 = 0x41;                           // 32kHz/9600 = 3.41 //for 32khz    3;
UCA0BR1 = 0x03;                           //                                      //    0;
UCA0MCTL = UCBRS1 + UCBRS0;               // Modulation UCBRSx = 3
UCA0CTL1 &= ~UCSWRST;                     // **Initialize USCI state machine**
TACCTL0 = CCIE;                            // TACCR0 interrupt enabled
IE2 |= UCA0RXIE;                          // Enable USCI_A0 RX interrupt
BCSCTL3 |= LFXT1S_2;

TACCR0=12000;
TACTL = TASSEL_1 + MC_1;
__bis_SR_register(LPM3_bits + GIE);       // Enter LPM3 w/ int until Byte RXed
}

#pragma vector=USCIAB0TX_VECTOR
__interrupt void USCI0TX_ISR(void)
{
UCA0TXBUF = string1[i++];                 // TX next character

if (i == sizeof string1 - 1)              // TX over?
    IE2 &= ~UCA0TXIE;                       // Disable USCI_A0 TX interrupt
}

#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCI0RX_ISR(void)
{
if (UCA0RXBUF == 'u')                     // 'u' received?
{
    i = 0;
    IE2 |= UCA0TXIE;                        // Enable USCI_A0 TX interrupt
    UCA0TXBUF = string1[i++];
}
}

0 Nikolai Kolev over 17 years ago in reply to SRIHK

Prodigy 110 points

Thanks SRIHK,

This is mainly UART example. For SPI may be I can use in addition clock on P2.1 - SMCLK.

Regards,

Nick.

0 Nikolai Kolev over 17 years ago in reply to Nikolai Kolev

Prodigy 110 points

I am not shure if it is possible to substitute P3.0 UCA0 CLK with another digital pin for SPI on A channel?

Nick

0 Brandon08 over 17 years ago in reply to Nikolai Kolev

TI__Mastermind 24490 points

levkolai said:

I am not shure if it is possible to substitute P3.0 UCA0 CLK with another digital pin for SPI on A channel?

Unfortunately, you cannot replace the USCI's chanel A SPI clock line because it is a hardware peripheral. This pin is available on the actual target board (pin 17, see page 8 of the User's Guide).

If you are unable to use the channel A clock pin you could implement a software SPI implementation. See the below code:

//******************************************************************************
// MSP430x11x1 Demo - Software SPI Interface TLC549, Set P1.0 if > 0.5*Vcc
//
// Description: Read a TLC549 ADC with reference to Vcc using software SPI and
// store the 8-bit digital code in ADCData. The TLC549 is sampled in a
// continous loop. If ADCData > 0.5*Vcc, P1.0 set, else reset.
// ACLK = n/a. MCLK = SMCLK = default DCO ~800k
// //* VCC must be at least 3v for TLC549 *//
//
//                       MSP430F1121
//                    -----------------
//                /|\|              XIN|-
//                 | |                 |
//                 --|RST          XOUT|-
//      TLC549       |                 |
//    ----------     |                 |
//   |        CS|<---|P2.0         P1.0|-->LED
// ~>| AIN+ CLK|<---|P2.1             |
//   |        DO|--->|P2.3             |
//
//
// M. Buccini
// Texas Instruments Inc.
// Feb 2005
// Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.21A
//******************************************************************************

#include <msp430x11x1.h>

#define CS              0x01                // P2.0 - Chip Select
#define CLK             0x02                // P2.1 - Clock
#define DO              0x08                // P2.3 - Data Out

void main (void)
{
unsigned char ADCData;
unsigned char Counter;
WDTCTL = WDTPW + WDTHOLD;                 // Stop watchdog timer
P2OUT = CS;                               // /CS set, - P2.x reset
P2DIR |= CLK + CS;                        // /CS and CLK outputs
P1DIR |= 0x01;                            // Set P1.0 to output direction

for (;;)                                  // Infinite loop
{
P2OUT &= ~CS;                             // /CS reset, enable ADC
for (Counter = 8; Counter > 0;)
    {
    ADCData = ADCData << 1;
      if ((P2IN & DO) == DO)
      {
      ADCData |= 0x01;
      }
    Counter --;
    P2OUT |= CLK;                           // Clock high
    P2OUT &= ~CLK;                          // Clock low
    }
P2OUT |= CS;                              // /CS set, disable ADC
    if (ADCData < 0x7F)
    {
    P1OUT &= ~0x01;                         // Clear P1.0 LED off
    }
    else
    {
    P1OUT |= 0x01;                          // Set P1.0 LED on
    }
}
}

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ez430-RF2500 SPI