tiva SPI slave mode interrupt and RX FIFO

/*
 * main.c
 */

#include <stdint.h>
#include <stdbool.h>
#include "driverlib/sysctl.h"
//#include "inc/tm4c123gh6pm.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "inc/hw_memmap.h"
#include "driverlib/ssi.h"
#include "driverlib/adc.h"
#include "driverlib/interrupt.h"
#include "driverlib/pin_map.h"
#include "driverlib/uart.h"
#include "inc/hw_ints.h"
#include "utils/uartstdio.h"
#include "driverlib/systick.h"

#define SSI0_CR1_R              (*((volatile uint32_t *)0x40008004))
#define SSI_CR1_SOD				0x00000008
#define NVIC_ST_CURRENT_R       (*((volatile uint32_t *)0xE000E018))
#define NVIC_ST_CTRL_R      	(*((volatile unsigned long *)0xE000E010))
#define dataLength				4
uint32_t returnData[dataLength] = {0};
uint32_t receiveData[dataLength] = {0};
uint32_t dataSent = 1;

//returns current system frequency which may not match requested frequency
void Clock_Init(){
	uint32_t ui32Config; //provides divisor of one the fixed PLL VCO settings
	//PLL is 400MHz: (400MHz/2)/4 = 50MHz
	ui32Config = (SYSCTL_SYSDIV_4 | SYSCTL_XTAL_16MHZ | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN);
	SysCtlClockSet(ui32Config);
}

void SysTick_Init(){
	//15e6/50e6 = 300ms period
	SysTickDisable();
	SysTickPeriodSet(15000000);
	SysTickEnable();
	NVIC_ST_CURRENT_R = 0;
}
//configure GPIO to use SSI0 on Port A, SSI1 on Port D
//and AIN0 from slide pot on pin PE3
//Nokia5110 DC
void GPIO_Init(){

	//SSI0 is for slave, SSI1 is for LCD

	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA); //for slave
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD); //for LCD
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE); //for ADC channels

	SysCtlDelay(100);

	SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI0);
	SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI1);
	SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);
	SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
	SysCtlDelay(3);
	GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);

	//PA2-5:
	GPIOPinTypeSSI(GPIO_PORTA_BASE, GPIO_PIN_2 | GPIO_PIN_3 | GPIO_PIN_4 | GPIO_PIN_5);
	//PD0-3:
	GPIOPinTypeSSI(GPIO_PORTD_BASE, GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_2 | GPIO_PIN_3);
	/*
	 * x axis: PE0 AIN3
	 * z axis: PE1 AIN2
	 * offloader force: PE2 AIN1
	 * temperature: PE3 AIN0
	 */
	GPIOPinTypeADC(GPIO_PORTE_BASE, GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_2 | GPIO_PIN_3);

	GPIOPinTypeGPIOOutput(GPIO_PORTD_BASE, GPIO_PIN_7);//for Data/Command to LCD
	GPIOPinTypeGPIOOutput(GPIO_PORTD_BASE, GPIO_PIN_6); //for reset to LCD
	GPIOPinTypeGPIOOutput(GPIO_PORTA_BASE, GPIO_PIN_6); //for SSI0 ISR signaling
	GPIOPinConfigure(GPIO_PA0_U0RX);
	GPIOPinConfigure(GPIO_PA1_U0TX);
	GPIOPinConfigure(GPIO_PA2_SSI0CLK);
	GPIOPinConfigure(GPIO_PA3_SSI0FSS);
	GPIOPinConfigure(GPIO_PA4_SSI0RX);
	GPIOPinConfigure(GPIO_PA5_SSI0TX);
	GPIOPinConfigure(GPIO_PD0_SSI1CLK);
	GPIOPinConfigure(GPIO_PD1_SSI1FSS);
	GPIOPinConfigure(GPIO_PD2_SSI1RX);//not used because LCD doesn't transmit back
	GPIOPinConfigure(GPIO_PD3_SSI1TX);
}

void UART_Init(){
	UARTClockSourceSet(UART0_BASE, UART_CLOCK_PIOSC);
	UARTStdioConfig(0, 9600, 16000000);
}

void SSI0_Handler() {
	GPIOPinWrite(GPIO_PORTA_BASE, GPIO_PIN_6, GPIO_PIN_6);
	//SSI0_CR1_R &= ~SSI_CR1_SOD; //0 in slave output disable bit in order to drive line
	SSIIntClear(SSI0_BASE, SSI_RXFF);
	//UARTprintf("");
	int i = 0;
	for(i = 0; i < dataLength; i++){
		//wait until a value is in the RX FIFO if there isn't one.
		SSIDataGet(SSI0_BASE, &receiveData[i]);
	}
	for(i = 0; i < dataLength; i++){
		UARTprintf("receiveData[%1d] = %08x\n", i, receiveData[i]);
	}
	dataSent = 1;
	UARTprintf("\n");
	//disable slave output
	//SSI0_CR1_R |= SSI_CR1_SOD;
	GPIOPinWrite(GPIO_PORTA_BASE, GPIO_PIN_6, 0x00);
}
//configure and enable the SSI peripheral. Slave mode requires CLK < 12 x system clock (master uC runs SPI at 1.17MHz)
//Using the same polarity and phase as F28M335x: Polarity 0, Phase 1
// means clock idle state is zero, sample takes place on 2nd clock edge
void SSI_Init(){

	SSIClockSourceSet(SSI1_BASE, SSI_CLOCK_SYSTEM); //Nokia5110 max f_sclk(ext) is 4.0MHz
	SSIConfigSetExpClk(SSI0_BASE, SysCtlClockGet(), SSI_FRF_MOTO_MODE_0, SSI_MODE_SLAVE, 3330000, 8);
	//Nokia5110 samples SDIN at positive edge of clock: phase bit should be 1, set idle clock high
	SSIConfigSetExpClk(SSI1_BASE, SysCtlClockGet(), SSI_FRF_MOTO_MODE_0, SSI_MODE_MASTER, 3330000, 8);
	SSIIntEnable(SSI0_BASE, SSI_RXFF); //SSI0_Handler() will be called when RXFF is half full or more
	//For SLAVE
	SSIEnable(SSI0_BASE);
	//For Nokia5110
	SSIEnable(SSI1_BASE);
}

//Configure Interrupts
void NVIC_Init(){
	IntEnable(INT_SSI0_TM4C123);
	IntPrioritySet(INT_SSI0_TM4C123, 0);
	IntMasterEnable();
}

void SysTick_Wait3sec(){
	int i;
	for (i = 0; i < 10; i++){
		while((NVIC_ST_CTRL_R & 0x00010000)==0){
		}
	}
}

int main(void) {
	Clock_Init();
	GPIO_Init();
	UART_Init();
	SSI_Init();
	SysTick_Init();
	int i;
	for (i = 0; i < 4; i++){
		returnData[i]=i;
	}
	NVIC_Init();
	while(1){
		//get data ready for master initiation
		//only put data in return FIFO if the last packet was sent
		if (dataSent){
			UARTprintf("loading return data\n");
			for (i = 0; i < dataLength; i++){
				SSIDataPut(SSI0_BASE, returnData[i]);
				UARTprintf("returnData[%d]: %08x\n", i, returnData[i]);
			}

			dataSent = 0;
		}

		//clear recieveData
		for (i = 0; i < dataLength; i++){
			receiveData[i] = 0;
		}
		UARTprintf("Main loop\n");
		SysTick_Wait3sec();
	}

	return 0;

}