Hi,
Can I use the following example demo code to transmit/receive a 16-bit SPI Frame using MSP430G2553?
This Demo code is from the TI CCS cloud resource for register level - MSP430G2553 device.
//******************************************************************************
// MSP430G2xx3 Demo - USCI_A0, SPI 3-Wire Master multiple byte RX/TX
//
// Description: SPI master communicates to SPI slave sending and receiving
// 3 different messages of different length. SPI master will enter LPM0 mode
// while waiting for the messages to be sent/receiving using SPI interrupt.
// SPI Master will initially wait for a port interrupt in LPM0 mode before
// starting the SPI communication.
// ACLK = NA, MCLK = SMCLK = DCO 16MHz.
//
//
// MSP430G2553
// -----------------
// /|\ | P2.0|-> Slave Chip Select (GPIO)
// | | |
// ---|RST P1.5|-> Slave Reset (GPIO)
// | |
// | P1.2|-> Data Out (UCA0SIMO)
// | |
// Button ->|P1.3 P1.1|<- Data In (UCA0SOMI)
// | |
// | P1.4|-> Serial Clock Out (UCA0CLK)
//
// Nima Eskandari
// Texas Instruments Inc.
// April 2017
// Built with CCS V7.0
//******************************************************************************
#include <msp430.h>
#include <stdint.h>
//******************************************************************************
// Example Commands ************************************************************
//******************************************************************************
#define DUMMY 0xFF
#define SLAVE_CS_OUT P2OUT
#define SLAVE_CS_DIR P2DIR
#define SLAVE_CS_PIN BIT0
/* CMD_TYPE_X_SLAVE are example commands the master sends to the slave.
* The slave will send example SlaveTypeX buffers in response.
*
* CMD_TYPE_X_MASTER are example commands the master sends to the slave.
* The slave will initialize itself to receive MasterTypeX example buffers.
* */
#define CMD_TYPE_0_SLAVE 0
#define CMD_TYPE_1_SLAVE 1
#define CMD_TYPE_2_SLAVE 2
#define CMD_TYPE_0_MASTER 3
#define CMD_TYPE_1_MASTER 4
#define CMD_TYPE_2_MASTER 5
#define TYPE_0_LENGTH 1
#define TYPE_1_LENGTH 2
#define TYPE_2_LENGTH 6
#define MAX_BUFFER_SIZE 20
/* MasterTypeX are example buffers initialized in the master, they will be
* sent by the master to the slave.
* SlaveTypeX are example buffers initialized in the slave, they will be
* sent by the slave to the master.
* */
uint8_t MasterType0 [TYPE_0_LENGTH] = {0x11};
uint8_t MasterType1 [TYPE_1_LENGTH] = {8, 9};
uint8_t MasterType2 [TYPE_2_LENGTH] = {'F', '4' , '1' , '9', '2', 'B'};
uint8_t SlaveType2 [TYPE_2_LENGTH] = {0};
uint8_t SlaveType1 [TYPE_1_LENGTH] = {0};
uint8_t SlaveType0 [TYPE_0_LENGTH] = {0};
//******************************************************************************
// General SPI State Machine ***************************************************
//******************************************************************************
typedef enum SPI_ModeEnum{
IDLE_MODE,
TX_REG_ADDRESS_MODE,
RX_REG_ADDRESS_MODE,
TX_DATA_MODE,
RX_DATA_MODE,
TIMEOUT_MODE
} SPI_Mode;
/* Used to track the state of the software state machine*/
SPI_Mode MasterMode = IDLE_MODE;
/* The Register Address/Command to use*/
uint8_t TransmitRegAddr = 0;
/* ReceiveBuffer: Buffer used to receive data in the ISR
* RXByteCtr: Number of bytes left to receive
* ReceiveIndex: The index of the next byte to be received in ReceiveBuffer
* TransmitBuffer: Buffer used to transmit data in the ISR
* TXByteCtr: Number of bytes left to transfer
* TransmitIndex: The index of the next byte to be transmitted in TransmitBuffer
* */
uint8_t ReceiveBuffer[MAX_BUFFER_SIZE] = {0};
uint8_t RXByteCtr = 0;
uint8_t ReceiveIndex = 0;
uint8_t TransmitBuffer[MAX_BUFFER_SIZE] = {0};
uint8_t TXByteCtr = 0;
uint8_t TransmitIndex = 0;
/* SPI Write and Read Functions */
/* For slave device, writes the data specified in *reg_data
*
* reg_addr: The register or command to send to the slave.
* Example: CMD_TYPE_0_MASTER
* *reg_data: The buffer to write
* Example: MasterType0
* count: The length of *reg_data
* Example: TYPE_0_LENGTH
* */
SPI_Mode SPI_Master_WriteReg(uint8_t reg_addr, uint8_t *reg_data, uint8_t count);
/* For slave device, read the data specified in slaves reg_addr.
* The received data is available in ReceiveBuffer
*
* reg_addr: The register or command to send to the slave.
* Example: CMD_TYPE_0_SLAVE
* count: The length of data to read
* Example: TYPE_0_LENGTH
* */
SPI_Mode SPI_Master_ReadReg(uint8_t reg_addr, uint8_t count);
void CopyArray(uint8_t *source, uint8_t *dest, uint8_t count);
void SendUCA0Data(uint8_t val);
void CopyArray(uint8_t *source, uint8_t *dest, uint8_t count)
{
uint8_t copyIndex = 0;
for (copyIndex = 0; copyIndex < count; copyIndex++)
{
dest[copyIndex] = source[copyIndex];
}
}
SPI_Mode SPI_Master_WriteReg(uint8_t reg_addr, uint8_t *reg_data, uint8_t count)
{
MasterMode = TX_REG_ADDRESS_MODE;
TransmitRegAddr = reg_addr;
//Copy register data to TransmitBuffer
CopyArray(reg_data, TransmitBuffer, count);
TXByteCtr = count;
RXByteCtr = 0;
ReceiveIndex = 0;
TransmitIndex = 0;
SLAVE_CS_OUT &= ~(SLAVE_CS_PIN);
SendUCA0Data(TransmitRegAddr);
__bis_SR_register(CPUOFF + GIE); // Enter LPM0 w/ interrupts
SLAVE_CS_OUT |= SLAVE_CS_PIN;
return MasterMode;
}
SPI_Mode SPI_Master_ReadReg(uint8_t reg_addr, uint8_t count)
{
MasterMode = TX_REG_ADDRESS_MODE;
TransmitRegAddr = reg_addr;
RXByteCtr = count;
TXByteCtr = 0;
ReceiveIndex = 0;
TransmitIndex = 0;
SLAVE_CS_OUT &= ~(SLAVE_CS_PIN);
SendUCA0Data(TransmitRegAddr);
__bis_SR_register(CPUOFF + GIE); // Enter LPM0 w/ interrupts
SLAVE_CS_OUT |= SLAVE_CS_PIN;
return MasterMode;
}
void SendUCA0Data(uint8_t val)
{
while (!(IFG2 & UCA0TXIFG)); // USCI_A0 TX buffer ready?
UCA0TXBUF = val;
}
//******************************************************************************
// Device Initialization *******************************************************
//******************************************************************************
void initClockTo16MHz()
{
if (CALBC1_16MHZ==0xFF) // If calibration constant erased
{
while(1); // do not load, trap CPU!!
}
DCOCTL = 0; // Select lowest DCOx and MODx settings
BCSCTL1 = CALBC1_16MHZ; // Set DCO
DCOCTL = CALDCO_16MHZ;
}
void initGPIO()
{
//LEDs
P1OUT = 0x00; // P1 setup for LED & reset output
P1DIR |= BIT0 + BIT5 + BIT6;
//SPI Pins
P1SEL = BIT1 + BIT2 + BIT4;
P1SEL2 = BIT1 + BIT2 + BIT4;
//Button to initiate transfer
P1DIR &= ~(BIT3);
P1OUT |= BIT3; // P1.3 pull up
P1REN |= BIT3; // P1.3 pull up/down resistor enable
P1IE |= BIT3; // P1.3 interrupt enabled
P1IES |= BIT3; // P1.3 Hi/lo edge
P1IFG &= ~BIT3; // P1.3 IFG cleared
}
void initSPI()
{
//Clock Polarity: The inactive state is high
//MSB First, 8-bit, Master, 3-pin mode, Synchronous
UCA0CTL0 |= UCCKPL + UCMSB + UCMST + UCSYNC;
UCA0CTL1 |= UCSSEL_2; // SMCLK
UCA0BR0 |= 0x20; // /2
UCA0BR1 = 0; //
UCA0MCTL = 0; // No modulation must be cleared for SPI
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
IE2 |= UCA0RXIE; // Enable USCI0 RX interrupt
SLAVE_CS_DIR |= SLAVE_CS_PIN;
SLAVE_CS_OUT |= SLAVE_CS_PIN;
}
//******************************************************************************
// Main ************************************************************************
// Send and receive three messages containing the example commands *************
//******************************************************************************
int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer
initClockTo16MHz();
initGPIO();
initSPI();
P1OUT &= ~BIT5; // Now with SPI signals initialized,
__delay_cycles(100000);
P1OUT |= BIT5; // reset slave
__delay_cycles(100000); // Wait for slave to initialize
P1OUT |= BIT0;
__bis_SR_register(LPM0_bits + GIE); // CPU off, enable interrupts
SPI_Master_ReadReg(CMD_TYPE_2_SLAVE, TYPE_2_LENGTH);
CopyArray(ReceiveBuffer, SlaveType2, TYPE_2_LENGTH);
SPI_Master_ReadReg(CMD_TYPE_1_SLAVE, TYPE_1_LENGTH);
CopyArray(ReceiveBuffer, SlaveType1, TYPE_1_LENGTH);
SPI_Master_ReadReg(CMD_TYPE_0_SLAVE, TYPE_0_LENGTH);
CopyArray(ReceiveBuffer, SlaveType0, TYPE_0_LENGTH);
SPI_Master_WriteReg(CMD_TYPE_2_MASTER, MasterType2, TYPE_2_LENGTH);
SPI_Master_WriteReg(CMD_TYPE_1_MASTER, MasterType1, TYPE_1_LENGTH);
SPI_Master_WriteReg(CMD_TYPE_0_MASTER, MasterType0, TYPE_0_LENGTH);
__bis_SR_register(LPM0_bits + GIE);
}
//******************************************************************************
// SPI Interrupt ***************************************************************
//******************************************************************************
#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))) USCIA0RX_ISR (void)
#else
#error Compiler not supported!
#endif
{
if (IFG2 & UCA0RXIFG)
{
uint8_t uca0_rx_val = UCA0RXBUF;
switch (MasterMode)
{
case TX_REG_ADDRESS_MODE:
if (RXByteCtr)
{
MasterMode = RX_DATA_MODE; // Need to start receiving now
//Send Dummy To Start
__delay_cycles(2000);
SendUCA0Data(DUMMY);
}
else
{
MasterMode = TX_DATA_MODE; // Continue to transmision with the data in Transmit Buffer
//Send First
SendUCA0Data(TransmitBuffer[TransmitIndex++]);
TXByteCtr--;
}
break;
case TX_DATA_MODE:
if (TXByteCtr)
{
SendUCA0Data(TransmitBuffer[TransmitIndex++]);
TXByteCtr--;
}
else
{
//Done with transmission
MasterMode = IDLE_MODE;
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}
break;
case RX_DATA_MODE:
if (RXByteCtr)
{
ReceiveBuffer[ReceiveIndex++] = uca0_rx_val;
//Transmit a dummy
RXByteCtr--;
}
if (RXByteCtr == 0)
{
MasterMode = IDLE_MODE;
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}
else
{
SendUCA0Data(DUMMY);
}
break;
default:
__no_operation();
break;
}
__delay_cycles(50);
}
}
//******************************************************************************
// PORT1 Interrupt *************************************************************
// Interrupt occurs on button press and initiates the SPI data transfer ********
//******************************************************************************
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=PORT1_VECTOR
__interrupt void Port_1(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(PORT1_VECTOR))) Port_1 (void)
#else
#error Compiler not supported!
#endif
{
P1OUT |= BIT6;
P1IFG &= ~BIT3; // P1.3 IFG cleared
P1IE &= ~BIT3;
//Initiate
__bic_SR_register_on_exit(LPM0_bits); // Exit LPM0
}
