ControlPins.c

#include "Timer32.h"
#include "Common.h"
#include "CortexM.h"
#include "SysTickTimer.h"
#include "ControlPins.h"
#include "ADC14.h"
#include "Camera.h"


extern uint32_t SystemCoreClock;
// default SI integration time is 7.5ms = 133Hz
//
#define INTEGRATION_TIME .0150f
//was 0.075



// default CLK frequency of the camera 180KHz (assume 48MHz clock)
// NOTE: we have to double 50000, because we need a clock for the rising edge and one for the falling edge.
//#define HIGH_CLOCK_SPEED 48000000

#define CLK_PERIOD ((double)SystemCoreClock/180000.0) 

// ADC_In() gets the latest value from the ADC
// ADC will be P4.7 A6
// SI Pin will be P5.5 A0
// CLK Pin will be P5.4 A1

static long pixelCounter = 0;

extern uint16_t line[128];
extern BOOLEAN dataAvaliable;


////////////////////////////////////////////
//
// this is the handler for the SI signal.
//
////////////////////////////////////////////
void SI_Handler(void)
{
	// the clock could stop when its high, so check on that
	if ((P5->OUT & CLK) != 0)
		P5->OUT &= ~CLK; // set the clock low in case it was high.
	// Read the TSL1401 instructions for SI, CLCK to start the data transfer process
	P5->OUT |= SI;
	// OK, Data should be ready to clock out, so start the clock
	P5->OUT |= CLK;

	P5->OUT &= ~SI;
	P5->OUT &= ~CLK;
	// Start the clock after we issues a SI pulse.
	EnableSysTickTimer();                            
}

// ADC_In() gets the latest value from the ADC
// ADC will be P4.7 
// SI Pin will be P5.5 
// CLK Pin will be P5.4 
//////////////////////////////////////////
//
// Init the SI timer
// using the Timer32-1 timer
// going to use pin P5.5
//
//////////////////////////////////////////
void ControlPin_SI_Init()
{
	// frequency of 133 Hz works OK, but could use more light
	// so try 50Hz?
	// Go with 50Hz for now - integration period of 20ms
	unsigned long period = CalcPeriodFromFrequency (1.0/(double)INTEGRATION_TIME);
	// initialize P5.5 and make it output (P5.5 SI Pin)
	P5->SEL0 &= ~BIT5;
	P5->SEL1 &= ~BIT5;
	P5->DIR  |= BIT5;
    // start Timer
	Timer32_1_Init(*SI_Handler, period, T32DIV1);
}

//////////////////////////////////////////
//
// Init the CLK timer
// using the SysTick base ARM timer
// going to use pin P5.4
//
//////////////////////////////////////////
void ControlPin_CLK_Init()
{
	// use 200000 to make a 100K clock, 1 interrupt for each edge
	unsigned long period = CalcPeriodFromFrequency (200000);
	// initialize P5.4 and make it output (P5.4 CLK Pin)
	P5->SEL0 &= ~BIT4;
	P5->SEL1 &= ~BIT4;
	P5->DIR  |= BIT4;
	// if the period is based on a 48MHz clock, each tick would be 20.83 ns
	// i want a 100KHz clock
	SysTickTimer_Init (*CLK_Handler, period);
	// stop the clock for now...
	DisableSysTickTimer();                           


}
// this is the handler for the CLK signal.
// on every clock pulse, we need to:
// 1. Toggle the CLK pin
// 2. If the CLK is high, read the value at the ADC A6
// 3. If I have read 128 pixels, 
//			set the g_sendData flag so the main program can send the data to the computer
//			disable the CLK timer
//
void CLK_Handler(void)
{
	unsigned int ADC_val;
	// toggle the clock
	P5->OUT ^= CLK;
	// check to see if clock is high
	if ((P5->OUT & CLK) != 0)
	{
		// read data from ADC
		ADC_val = ADC_In();
		// save into the line buffer
		line[pixelCounter] = ADC_val;
		// increment the pixelCounter
		pixelCounter = (pixelCounter + 1);
		//are we done??
		if (pixelCounter == 128)
		{
			dataAvaliable = TRUE;
			// stop the clock until the next SI pulse
			DisableSysTickTimer(); 	// stop the clock       
			pixelCounter = 0; 			// reset the counter
		}
	}	
}