Part Number: TMS320F28379D
Hello everyone,
I am working with the SPI module on the F28379D board. On my master end, I currently have my character length set to 16 bits. However, I wish to change this to 8 bits. When I attempt to do this by setting the SPI character control bits to 8 as follows: SpiaRegs.SPICCR.bit.SPICHAR = 0x7, I stop getting any data written altogether on my MOSI line.
I've tested this by transmitting 0xAA and 0xAAAA, when the SPICHAR bits are set to 8 and 16 bits respectively. When they are set to 16 bits, I get the correct transmission show up on my oscilloscope. However, when they are set to 8 bits, I get nothing on my SDI line.
I wanted to figure out why this is happening and how I can fix it.
Below are my oscilloscope plots:
Scope when SPICHAR = 16 bits (data transmitted on SDI 0xAAAA)
Scope when SPICHAR = 8 bits (data transmitted on SDI 0xAA)
Below is my code listing
// Included Files
#include "preprocessor.h"
#include "F28x_Project.h"
#include "spi_globals.h"
#include "spi_defines.h"
#include "function_defs.h"
void scan_test(void);
void main(void)
{
/*INITIALISATION----------------------*/
// SETUP CLOCK FREQUENCY
EALLOW;
// ClkCfgRegs.LOSPCP.bit.LSPCLKDIV = 0b100;
EDIS;
/* SETUP CODE */
// PRELIMINARY STEPS
InitSysCtrl(); // Step 1. Initialize System Control:
InitSpiaGpio(); // Step 2. Initialize GPIO:
DINT; // Step 3. Clear all interrupts:
InitPieCtrl(); // Initialize PIE control registers to their default state.
// Disable CPU __interrupts and clear all CPU __interrupt flags:
IER = 0x0000;
IFR = 0x0000;
// Initialize the PIE vector table with pointers to the shell Interrupt Service Routines (ISR).
InitPieVectTable();
// Step 4. Initialize the Device Peripherals:
spi_fifo_init(); // Initialize the Spi FIFO
spi_init(); // init SPI
/*COMMAND SECTION----------------------*/
// TRANSMIT ON SDI
// SpiaRegs.SPITXBUF = 0xAA;
SpiaRegs.SPITXBUF = 0xAAAA;
}
Below is my setup for the SPI registers (also note, I am not using FIFO enhancements):
void spi_init()
{
// BIT FIELD SETUP
//---------------------------------------------------------------------------------------------------------------------
EALLOW;
// SPI CONFIFURATION CONTROL REGISTER // Reset on, rising edge, 16-bit char bits
SpiaRegs.SPICCR.bit.SPISWRESET = 0; // BIT 7 // SPI Software Reset
SpiaRegs.SPICCR.bit.CLKPOLARITY = 0; // BIT 6 // Shift Clock Polarity
SpiaRegs.SPICCR.bit.HS_MODE = 0; // BIT 5 // High Speed Mode Enable Bits
SpiaRegs.SPICCR.bit.SPILBK = 0; // BIT 4 // SPI Loopback Mode Select
// SpiaRegs.SPICCR.bit.SPICHAR = 0xF;
SpiaRegs.SPICCR.bit.SPICHAR = 0x7;
// BIT 0-3 // Character Length Control Bits
// SPI OPERATION CONTROL REGISTER // Enable master mode, normal phase,
// ------------------------------ // enable talk, and SPI int disabled.
SpiaRegs.SPICTL.bit.OVERRUNINTENA = 0; // BIT 4 // Overrun Interrupt Enable
SpiaRegs.SPICTL.bit.CLK_PHASE = 1; // BIT 3 // SPI Clock Phase Select
SpiaRegs.SPICTL.bit.MASTER_SLAVE = 1; // BIT 2 // SPI Network Mode Control
SpiaRegs.SPICTL.bit.TALK = 1; // BIT 1 // Transmit Enable
SpiaRegs.SPICTL.bit.SPIINTENA = 0; // BIT 0 // SPI Interrupt Enable
// SPI BAUD RATE REGISTER
SpiaRegs.SPIBRR.bit.SPI_BIT_RATE = 29;
// SPI CONFIFURATION CONTROL REGISTER // Relinquish SPI from Reset
SpiaRegs.SPICCR.bit.SPISWRESET = 1; // BIT 7
// SpiaRegs.SPICCR.bit.CLKPOLARITY = 0; // BIT 6
// SpiaRegs.SPICCR.bit.HS_MODE = 0; // BIT 5
// SpiaRegs.SPICCR.bit.SPILBK = 0; // BIT 4
// SpiaRegs.SPICCR.bit.SPICHAR = 15; // BIT 0-3
// SPI PRIORITY CONTROL REGISTER
SpiaRegs.SPIPRI.bit.FREE = 1; // Set so breakpoints don't disturb xmission
EDIS;
}
