PIC16f690, initialisation of ports, LEDS,reading from a pin

[be80be]

A pic 16f690 can do 16 bit math the compiler handles it for you
How long do you you have to get this to work fanta?
The 18f1320 is 8 bit to lol
16 bit chips are pic24f pic24h dspic30 dspic33
and the pic32 it's 32 bit

 

[fantabulous68]

lol OK,, uhmmmm im new with the programming guys-sorry for asking alot of silly questions...just want to make sure i do it right this time. I have like a month and 1week left be80be.

 

[ericgibbs]

lol OK,, uhmmmm im new with the programming guys-sorry for asking alot of silly questions...just want to make sure i do it right this time. I have like a month and 1week left be80be.

hi,
I would recommend that you try the Sharp GP2 opto to check that it will work from the water surface over the range you require.

A clear water surface is a very poor reflector for IR or visible light, just look into a bowl of water and you see how little it reflects at 90deg.

 

[fantabulous68]

Yeah i will do that when the GP2 arrives, Im not constrained to using water. I just have to test which liquids it works best with, and add those to my final specifications and use those to demonstrate with.

 

[fantabulous68]

Programming the Sharp GP2 sensor PIC16f690

This is for the PIC 18F1320 BUT i want to modify this code to suit the PIC16f690. I am trying but not sure about a few things. I attached a word document with the relevent datasheets from the 18F and 16F.

void main()
{
	// setup the [B]PIC 18F1320[/B]
	OSCCON = 0x72;      	// internal osc, 8MHz

	PORTA = 0;
	[COLOR="Red"]TRISA = 0b10000010;[/COLOR] 	// RA7 high imp, RA3 is serial out,
							// RA1 is ADC input measuring VR1
	PORTB = 0;
	INTCON2 = 0;            // PORTB pullups ON
	TRISB = 0b00000000; 	// PORTB not used

[COLOR="Indigo"]	ADCON0 = 0b00000101;	// ADC ON, RA1 is ADC input
	ADCON1 = 0b01111101;	// AN1 is ADC input
	ADCON2 = 0b10100010;	// right justify, [B][I]8Tad[/I][/B], 32Tosc[/COLOR]

	T1CON = 0b00010001;     // TMR1 is ON, 1:2 prescale, =1MHz

	T3CON = 0b00010001;     // TMR3 is ON, 1:2 prescale, =1MHz

	// main loop here;
	while(1)
	{
		// wait for 2 seconds, uses TMR1 free running at 1Mhz
		while(!PIR1.TMR1IF);    // wait for TMR1 overflow
        PIR1.TMR1IF = 0;		// clear overflow flag
		LATA = 0;				// all LEDs off
		
		bres += 65536;			// add 65536uS to bres value
		if(bres >= 2000000)		// if reached 2 seconds!
		{
			bres -= 2000000;	// subtract 2 seconds, keep error
		
			// flash Junebug LED1,  RA0=1 RA6=0 RA7=hiimpedance
			LATA.F0 = 1;			// LED on

		    // read the ADC voltage RA1 (Sharp GP2 sensor)
		    ADCON0.F1 = 1;		// set GO bit, start doing ADC
		    while(ADCON0.F1);	// wait until ADC done
			calc_distance();		// convert ADC value to distance
			send_serial_message();	// send message back to PC!
		}

	}
}

My code to suit pic 16f690:

	[COLOR="Red"]TRISA = 0b10000010;[/COLOR] 	// RA7 high imp, RA3 is serial out,
				// RA1 is ADC input measuring VR1

Question1:The 16f690 doesnt have a RA7. What does makin the pin a high impedance mean? Im assuming imp is impedance. I know TRIS sets pins as inputs and outputs.

*********************************************************
Im sure this part is rightEasy part
//18F

PORTB = 0;
INTCON2 = 0;            // PORTB pullups ON
TRISB = 0b00000000; 	// PORTB not used

//16F

PORTB = 0;          
WPUB = 1;
RABPU = 0;

*********************************************************

//18F

[COLOR="Indigo"]ADCON0 = 0b00000101;	// ADC ON, RA1 is ADC input
ADCON1 = 0b01111101;	// AN1 is ADC input
ADCON2 = 0b10100010;	// right justify, 8Tad, 32Tosc[/COLOR]

//16F

ADCON0 = 0b10000101;	// bit 7 right justify,analogue channel select bits bits5-2  0001=AN1,ADC ON, RA1 is ADC input
ADCON1 = 0b00100000;	//bits6-4  fosc/32

Question2:
I dont know how to set 8Tad on the 16f690. Could someone please tell me how to do that?

Question3:
Does analogue channel select bits bits5-2 0001=AN1 mean that AN1 is ADC input?


Im going to collect the sharp GP2 today

 

[fantabulous68]

Any comments on the quote below? I already stopped with my TOF approach to this design.

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Join Date: Jun 2009
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Your not at programming yet, as the hardware isn't proven.

Here's a contemplation;

If you issue the IR radiation, and at the same time start an RC charge ramp. The detector then would cease and hold the charge, for the micro to AD convert, or drain the charge at a different rate that is complatable with the micro.

You will need a high power emitter and a sensitive reciever.

Another approach could be to charge a capacitive gate for the TOF duration, then inspect the gate effect.

Your problem is not in the pics timers, as you would only use them to time the sampling rate, but in the gating of your signals used to capture the TOF.