Problem Programming PIC18LF8720

[Juansta12]

Im trying to program a bootloader into a PIC18LF8720 with no luck.

I have built a JDM programmer and a SCHAER+ programmer and both fail.

My PC Sees the programmer with no problem, but does not recognise the PIC.

Currently as this is the 3.3V version, the PIC is the only device on the circuit, with the following lines tied into the programmer;
1. MCLR
2. Prog Data
3. Prog Clk
4. +5V
5. GND

I have not tied PGM to anything, should I? Or is this only to carry out LVP?

As there is nothing else on the board at the moment I dont know what else could be causing this?



Any help would be greatly appreciated!

 

[tunedwolf]

I suspect a timing issue with your programmer software is to blame....but could also be a sagging voltage somewhere, or not resetting the device properly prior to entering programming mode.

 

[Juansta12]

I have tried using;
1. IC-Prog
2. PICPgm
3. PP18

and the voltages Im getting are;
MCLR - 12.3V
Vcc - 5.1V
Clk/Data - 5.1V

 

[tunedwolf]

the mclr/vpp is a smidge low, but only a smidge...it may not be the cause of your problems though...

have you checked the errata sheets for the chip ?
perhaps microchip have altered something in the later silicon...

I have just looked at a circuit of the schaer+ programmer...what a dissappointing power supply

I have attached here a copy of a programmer I have built and used successfully with loads of PIC's using the IC-Prog software. Maybe if you modify the power supply of your programmer, you will have better luck...

 

[Pommie]

PGM should be tied low.

Mike.