El Cheapo prog + PIC16F628 + IC-Prog Help!

[HRioux]

Hello all,
I've build the homebuild version of the El Cheapo programmer from here. This circuit is build on a breadboard and should work with every parallel port available on a PC. I'm running WIN98 and the prog is cabled with a 3' "Straight Through" parallel cable. I'm using an external power source of 14VDC/360mA.

IC-Prog settings are:
PIC 16F628 (without ending "A" since the PIC is 16F628-20/P);
El Cheapo programmer;
Ports = LPT1;
Interface = Direct I/O;
I/O delay = 10;
Communication = nothing tick.

Reading the PIC gives "Address - Program Code" 3FFF and "Address - Eeprom Data" FF.

I started troubleshooting the PIC as describe by eblc1388:
With no PIC in the socket,
1. pin 14 and tick the box "Enable Vcc", you should be able to control the +5V ON/OFF

2. pin 4, tick box "Enable MCLR", +13V On with tick, OFF without tick

3. pin 12, tick box "Enable Clock", +5V with tick, OFF without

4. pin 13, tick box "Enable Data Out", +5V and a tick will automatically appears in the "Singal In" box. Tick the box again and the condition returns to normal

Only test 1 fail. Reading all the time +5V. It look like I cannot control +5V ON/OFF.

When I'm trying to program the pic I get: verified failed at address 0000h.

Anyone familiar with this problem and could help me with a solution? I surely appreciate it.

Regards,
Hugo

 

[eng1]

With that programmer Vcc is not controlled by the signal coming from the parallel port. It is tied to 5.1 V

 

[HRioux]

Thanks eng1 for your reply.
Should I understand that because Vcc is tied to 5.1V, and that IC-Prog can read the PIC, the code is faulty.
Hugo

 

[Pommie]

I would suggest a pull down resistor on Mclr - a 10k resistor between pins 4 & 5 will do it. This stops pics that are programmed to use the internal RC oscillator from executing the code when Vdd is applied. Another possible explanation is that you have code protect on, change the settings to "verify during programming" under settings/options/programming.

Mike.

 

[HRioux]

Thank you Pommie for your suggestion. I have tried 10k resistor between pins 4 & 5 and have changed the settings to "verify during programming" without luck.

I am realy lost!

Any other suggestions are welcome. Thank you.

Regards,
Hugo

 

[Pommie]

Try downloading WinPic and reading the Help File and FAQ.

I find the above software more usable and the supporting documentation very useful.

Mike.

 

[HRioux]

Pommie, thanks for the tips.

One thing, I have tick "Invert Data In" in settings/hardware. I have no more error Verify failed at address 0000h ! with programming options "Verify during programming" ticked but error persist when I use "verify after programming".

I think I'm done. It is working well.

Thank you so much for your input.

Best regards,
Hugo