// E85 Lab 8: Digital Level
// Cherie Ho and David Money Harris
// Based on Bryce's SPI + GPIO STM32F0 CMSIS example

#include "stm32f0xx.h"
#include "EasyNucleoIO.h"

/////////////////////////////////////////////////////////////////////
// SPI Functions
/////////////////////////////////////////////////////////////////////

#define ALT 2

void spiInit() {
	//set ALT function for SPI pins
	pinMode(17, ALT); // PA4/SPI1_NSS (A3)
	pinMode(18, ALT); // PA5/SPI1_SCK (A4)
	pinMode(19, ALT); // PA6/SPI1_MISO (A5)
	pinMode(20, ALT); // PA7/SPI1_MOSI (A6)

	//configure SPI:		
	//SPI enabled -> SPE; BAUD rate -> BR; Master -> MSTR;
	//BR = fclk/8, master mode
	SPI1->CR1 |= SPI_CR1_BR_1 | SPI_CR1_MSTR;
	// Enable NSS select signal, pulse NSS between transfers, 16-bit data, 
	SPI1->CR2 |= SPI_CR2_SSOE | SPI_CR2_NSSP | (0xF) << 8;
	//enable SPI
	SPI1->CR1 |= SPI_CR1_SPE;
}

//send a 16-bits (short) on SPI1 
unsigned short SPI1SendReceive16(unsigned short outDat) {
		SPI1->DR = outDat;
		while(!(SPI1->SR & SPI_SR_RXNE)); // wait for response
		return SPI1->DR; 
}

void spiWrite(unsigned char address, unsigned char value) {
	SPI1SendReceive16(address << 8 | value);
}

unsigned char spiRead(unsigned char address) {
	return SPI1SendReceive16(address << 8 | (1 << 15)); 
}

/////////////////////////////////////////////////////////////////////
// Digital Level logic
/////////////////////////////////////////////////////////////////////

int main(void)
{		
	volatile unsigned char debug;
	volatile short x,y, disx,disy;

	//setup clocks and hardware
	EasyNucleoIOInit();
	spiInit(); // Initialize SPI pins and clocks
	
	//Setup the LIS3DH for use
	spiWrite(0x20, 0x77); // highest conversion rate, all axis on
	spiWrite(0x23, 0x88); // block update, and high resolution
	
	// Check WHO_AM_I register. should return 0x33
	debug = spiRead(0x0F);
	
	while(1)
	{
		// Collect the X and Y values from the LIS3DH 	
		x = spiRead(0x28) | (spiRead(0x29) << 8);
		y = spiRead(0x2A) | (spiRead(0x2B) << 8);
		
		// Small delay to reduce flicker
		delayLoop(100);
	}	
}