[SOLVED] oops ! programmed pic RB6 and RB7 pins as outputs and now I can't program it any more

[techristian]

oops ! programmed pic RB6 and RB7 pins as outputs and now I can't program the PIC any more.

Anyway, that is the way it seems. It seemed like I was able to program with the PICKIT 3 even after this but the program never seemed to run right. Now the PICKIT3 won't even recognize the DEVICE ID.

Dan

 

[tpetar]

What PIC, what code, and what circuit ?

Maybe you fry µC or you just activate configuration bit for self destruction. :smile:

 

[techristian]

I'm still working with 16F1787 ....or was. Those 2 pins are connected to ICSP for programming. This is just to light led segments.

#include <p16f1787.inc>

;CONFIG1
; __config 0x3FE4
__CONFIG _CONFIG1, _FOSC_INTOSC & _WDTE_OFF & _PWRTE_OFF & _MCLRE_ON & _CP_OFF & _CPD_OFF & _BOREN_ON & _CLKOUTEN_OFF & _IESO_ON & _FCMEN_ON
; CONFIG2
; __config 0x3FFF
__CONFIG _CONFIG2, _WRT_OFF & _VCAPEN_OFF & _PLLEN_ON & _STVREN_ON & _BORV_LO & _LPBOR_OFF & _LVP_ON


org 0x0000

movlw LFIOFR ;LOW FREQUENCY
movwf OSCSTAT
delay equ 0x0c ;first general purpose register
digit equ 0x0d
digmask equ 0x0e
value equ 0x0f



goto start
org 0x004
goto isrv

start
movlw SCS0
iorwf IRCF0
movwf OSCCON
movlw b'00000000' ;MOVE ZERO TO ACC "W"orking register


TRIS 5 ;set PortA all outputs
TRIS 6 ;set PortB all outputs

 

[tpetar]

Did you check all connections with PICKit 3 ?

If PICKit dont see uC, maybe uC have general problem.

I have several times situations where one or two pins refuse to work. uC was new, intact and original, never used before by me.

 

[123jack]

TIP
I've had a couple of pics that didnt work "out of the tube" but after blanking a couple of times started to work.
None of them have failed subsequently.
I wish I could explain this but I can't.

 

[ard]

I dont know if the Pickit3 has it, but Pickit2 has an option for 'Use Vpp First Program Entry' under 'Tools'; I'd check that and see if that helps.

Regards,

Anand

 

[techristian]

TIP
I've had a couple of pics that didnt work "out of the tube" but after blanking a couple of times started to work.
None of them have failed subsequently.
I wish I could explain this but I can't.

I can't even erase the chip now. Here is the output that I get when I try to program or erase.

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

Connecting to MPLAB PICkit 3...
Firmware Suite Version.....01.28.57
Firmware type..............Enhanced Midrange

Target detected
Failed to get Device ID

 

[tpetar]

Some wires for programming are not connected or you have pic as french fries.

 

[techristian]

I'm thinking now that my test circuit didn't have proper voltage and fried the chip.

Dan

 

[techristian]

Just to clarify what actually happened...............

The problem had nothing to do with the programming. When I measured the voltage it seemed like there was exactly 4.8V between the 2 outside pins of my regulator so I thought that pin 1 was GND and pin 3 was OUTPUT. However in reality pin 1 was INPUT and pin 2 was ground. There were no markings on the regulator, but now I know it was a 7805 type. When I tried to pull power off of this , for my test circuit, I fried the PIC ..so I'm using a PIC16F1784 now...and have 2 more on order from MICROCHIP.

BUT I DIDN'T FRY MY PICKIT3 ! WHEWWWWWW !

(I WAS BORROWING POWER OFF OF MY VELLEMAN FOR THE BREADBOARD) There is no longer power to the Velleman. I now program the chips with power from the PICKIT3 plugged into the ISCP on the Velleman. I'll be modifying an old AT power supply to get a 5V DC supply for my breadboards, from now on.

Dan

 

[tpetar]

French fries is popular these days on EDAboard.


For AT psu maybe is better to use 12V rail and with 7805 with adequate capacitors make stable and ripple free 5V supply.

You can use 7805, 7812, regulator for 3,3V, all in SMD, also with SMD capacitors, all on small PCB on unvisible bottom side of breadboard. Take some mains wall adapter with around 15V for supply. On upper side make supply connectors for each stabilized voltage rails.

I implement small Li-Po battery on that way with voltage boosters for testing on field. LiPo can be rechargerd, and small charger is also on bottom side. Even small solar cell can recharge battery.

You can even implement small multichannel ampermeter with voltmeter on single 2x16 LCD, and low current led signalization.

All in one.

Usually breadboard - protoboard is piece of PVC with conductor rails for connections, but with this additional components can be very fast, reliable and usefull tool. Without thinking what power supply to use and where is it now.

;-)

 

[techristian]

Thanks tpetar !!

I was just going to use the 5V directly from the RED wire of the ATX power supply, but if you think putting
+12V through the 7805 is a good idea?...then I'll try that as well. I labelled all of the wires voltage from the ATX (after shorting green to black to turn it on) I found 3.3v coming from the orange wire and -11 volts from the blue wire. The grey and purple wire also were +5V but I'm not sure if they are regulated and what current capacity they have.

A tutorial I have been reading also recommends a 100nf cap across the +5 power to get rid of noise and spikes.

Thanks again

Dan

 

[tpetar]

Yes, freely use 7805 on 12V, you should use smaller currents on breadboard. Also all parts can be in SMD soldered on PCB copper as heatsink.

Yes there is 3,3V from ATX, and negative also.

Use always 100nF near supply pins of IC or uC.

 

[techristian]

I tried to get 100nf but they are sending me 82nf which is very close.

Dan

 

[tpetar]

Where they found 82nF I never use that value. Should be 100nF, I dont know for 82nF its close but its not 100nF.

Maybe they send used parts.