I am using the PIC18f46k42 microcontroller, XC8 2.3, with MPLABX/ MCC. My goal is to use the single SPI hardware peripheral to interface with multiple devices using various GPIO pins as chip selects. I have an LCD and an SD card that both need to talk to the MCU (obv not at the same time). My issue is when I try to change the SPI hardware configuration registers to switch between devices. So I tried reducing the problem and have come to this:
If I only use one spi configuration to drive the screen, it works. However if I try to close that spi connection and then reopen the same spi connection, the screen doesnt work. I believe the issue then lies in the SPI1_Open() generated by mcc.
spi1.h:
#ifndef SPI1_MASTER_H
#define SPI1_MASTER_H
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
/* SPI interfaces */
typedef enum {
SPI1_DEFAULT
} spi1_modes_t;
void SPI1_Initialize(void);
bool SPI1_Open(spi1_modes_t spi1UniqueConfiguration);
void SPI1_Close(void);
uint8_t SPI1_ExchangeByte(uint8_t data);
void SPI1_ExchangeBlock(void *block, size_t blockSize);
void SPI1_WriteBlock(void *block, size_t blockSize);
void SPI1_ReadBlock(void *block, size_t blockSize);
void SPI1_WriteByte(uint8_t byte);
uint8_t SPI1_ReadByte(void);
#endif //SPI1_H
spi1.c:
#include "spi1.h"
#include <xc.h>
typedef struct {
uint8_t con0;
uint8_t con1;
uint8_t con2;
uint8_t baud;
uint8_t operation;
} spi1_configuration_t;
//con0 == SPIxCON0, con1 == SPIxCON1, con2 == SPIxCON2, baud == SPIxBAUD, operation == Master/Slave
static const spi1_configuration_t spi1_configuration[] = {
{ 0x3, 0x60, 0x2, 0x3, 0 }
};
void SPI1_Initialize(void)
{
//EN disabled; LSBF MSb first; MST bus master; BMODE every byte;
SPI1CON0 = 0x03;
//SMP Middle; CKE Active to idle; CKP Idle:High, Active:Low; FST disabled; SSP active high; SDIP active high; SDOP active high;
SPI1CON1 = 0x60;
//SSET disabled; TXR required for a transfer; RXR data is not stored in the FIFO;
SPI1CON2 = 0x02;
//CLKSEL FOSC;
SPI1CLK = 0x00;
//BAUD 3;
SPI1BAUD = 0x03;
TRISCbits.TRISC1 = 0;
}
bool SPI1_Open(spi1_modes_t spi1UniqueConfiguration)
{
if(!SPI1CON0bits.EN)
{
SPI1CON0 = spi1_configuration[spi1UniqueConfiguration].con0;
SPI1CON1 = spi1_configuration[spi1UniqueConfiguration].con1;
SPI1CON2 = spi1_configuration[spi1UniqueConfiguration].con2 | (_SPI1CON2_SPI1RXR_MASK | _SPI1CON2_SPI1TXR_MASK);
SPI1CLK = 0x00;
SPI1BAUD = spi1_configuration[spi1UniqueConfiguration].baud;
TRISCbits.TRISC1 = spi1_configuration[spi1UniqueConfiguration].operation;
SPI1CON0bits.EN = 1;
return true;
}
return false;
}
void SPI1_Close(void)
{
SPI1CON0bits.EN = 0;
}
uint8_t SPI1_ExchangeByte(uint8_t data)
{
SPI1TCNTL = 1;
SPI1TXB = data;
while(!PIR2bits.SPI1RXIF);
return SPI1RXB;
}
void SPI1_ExchangeBlock(void *block, size_t blockSize)
{
uint8_t *data = block;
while(blockSize--)
{
SPI1TCNTL = 1;
SPI1TXB = *data;
while(!PIR2bits.SPI1RXIF);
*data++ = SPI1RXB;
}
}
// Half Duplex SPI Functions
void SPI1_WriteBlock(void *block, size_t blockSize)
{
uint8_t *data = block;
while(blockSize--)
{
SPI1_ExchangeByte(*data++);
}
}
void SPI1_ReadBlock(void *block, size_t blockSize)
{
uint8_t *data = block;
while(blockSize--)
{
*data++ = SPI1_ExchangeByte(0);
}
}
void SPI1_WriteByte(uint8_t byte)
{
SPI1TXB = byte;
}
uint8_t SPI1_ReadByte(void)
{
return SPI1RXB;
}
main.c:
#include "mcc_generated_files/mcc.h"
#include "ST7735.h"
#define led0 PORTAbits.RA7
#define led1 PORTAbits.RA6
#define led2 PORTAbits.RA5
#define led3 PORTAbits.RA4
void main(void)
{
// Initialize the device
SYSTEM_Initialize();
led0 = SPI1_Open(SPI1_DEFAULT);
led0 = SPI1CON0bits.EN;
LCD_RESET = 1;
delay_us(500);
LCD_RESET = 0;
delay_us(500);
LCD_RESET = 1;
delay_us(500);
__delay_ms(1000);
ST7735_initR();
ST7735_fillScreen(ST7735_BLACK);
while (1)
{
// Add your application code
}
}
I can include as well what's in ST7735.h/ST7735.c but I'm certain they are fine because they work just fine when spi1 is configured normally. The poor behavior only starts when I try to toggle the spi configuration which I must do in order to inevitably toggle between multiple devices. In the above code, SPI is defaulted to EN=0. I can include the version where SPI is defaulted EN=1 and uses SPI1_Close() to toggle it off. However both behave the same and this version is slightly simpler. I greatly appreciate any input you might have.
