Oilmex PIC-MT-USB and PIC16F877A

[taitny]

I picked up PIC-MT-USB from Olmex, and have been totally unable to write a PICBASIC program that runs on it.

For starters all I want to do light up the LED.

To add to my embarassment, Olimex even publishes C code and the associated HEX. The hex code runs just fine. I have not been able to figure out how to .. Convert .. the C, or create my own code that can turn on the light.

I am a newbie to MCUs (most of my programming skills are discrete TTL or CMOS), and have one simple project under my belt. This was the next step, but I am stuck.

This is the link to the board: http://www.olimex.com/dev/pic-mt-usb.html

Any experience or help welcome.

Thanks!

[DaveC3]

Be sure to set the configuration to HS, the standard 877A.inc file is set to XT.

;****************************************************************
;*  16F877A.INC                                                 *
;*                                                              *
;*  By        : Leonard Zerman, Jeff Schmoyer                   *
;*  Notice    : Copyright (c) 2003 microEngineering Labs, Inc.  *
;*              All Rights Reserved                             *
;*  Date      : 11/06/03                                        *
;*  Version   : 2.45                                            *
;*  Notes     :                                                 *
;****************************************************************
        NOLIST
    ifdef PM_USED
        LIST
        include 'M16F87xA.INC'  ; PM header
        device  pic16F877A, HS_osc, wdt_on, lvp_off, protect_off
        XALL
        NOLIST
    else
        LIST
        LIST p = 16F877A, r = dec, w = -302
        INCLUDE "P16F877A.INC"  ; MPASM  Header
        __config _HS_OSC & _WDT_ON & _LVP_OFF & _CP_OFF
        NOLIST
    endif
        LIST

Here is the C code to blink the leds

#include <pic.h> 

__CONFIG(UNPROTECT & PWRTEN & HS & BORDIS & WDTDIS & LVPDIS);

#define		LED1		RB2
#define		LED2		RB1

//Just simple delay
void Delay(unsigned long cntr) {
	while (--cntr != 0);
}

int main(void) {

	INTCON 	= 0x0;			// Disable inerupt
	TRISB1 	= 0;			// Led1 pin as output
	TRISB2 	= 0;			// Led2 pin as output


	while(1) {
		// led 1 on
		LED1 = 1;
		// led 2 off
		LED2 = 0;
		// Simple delay
		Delay(50000);
		// led 1 off
		LED1 = 0;
		// led 2 on
		LED2 = 1;
		// Simple delay
		Delay(50000);
	}

}

Here is a Picbasic translation

LED1   VAR PORTB.2
LED2   VAR PORTB.1

TRISB = %00000000

Main:

HIGH LED1
LOW LED2
Pause 500
LOW LED1
HIGH LED2
Pause 500

GOTO Main
end

Should work

Good luck

[taitny]

"Be sure to set the configuration to HS, the standard 877A.inc file is set to XT."

So I tired to compile the .inc file. THAT met with failure. Finally removed program(s) and reinstalled. the .inc file I found first was someting completely different.

Finaly, with subborness that is only matched by my ignorance, I stumbled across the .inc file in the PBP directory, and replaced it with the code that was posted in the previous post, and then compiled and ran the code.

Works great.

So, my next quesiton has to do with how do I know when to change configuration from HS to XT?

Clearly my education is lacking.. Pointers to where I can gain wisdom on the configuration files and need to change them would be welcom.

Thanks again!

Robert

[DaveC3]

Robert

HS is 20 Mhz crystal or resonator
XT is 4 Mhz crystal or resonator

Take a look at your chips data sheet, it will become your best friend. The section under oscillator configurations will tell all.

Have fun

[taitny]

I don't think I spend more than two hours going over 232 pages of 16F87X informaion, and still not not come back with a clue. It's a little overwhelming, but, now with the pointer to the XT, LP or HS modes, I can spend a couple of hours understanding that little bit.

Then there is the thought that even if I knew I had to change to HS mode, I would not have a clue how to do that without the first post. Maybe that's in the manual for the compiler, but I have not come across it yet.

With the help of this group, I am sure to gain wistom quicly.

I was even able to talk to the LC display, so yep, I AM having fun!

[Archangel]

Hi taitny,
OSC works sort of this way, remember the old axiom "speed costs money, how fast do you want to go" ? Sort the same here, "Speed costs energy, how fast do you want to go"?
setting the OSC to XT gives the OSC less power to play with than HS does. and the settings that allow 32KC OCS give even less, generally you want HS if you go over 4mhz.