PIC18F2550-I/SP programming issues

[Firelord]

Wired like this:

Pin 1 --> 10k resistor --> Pin 20 VDD
Pin 20 --> 5V
Pin 19 --> GND --> DB9 Pin 5
Pin 26--> 10k --> DB9 Pin 3
Pin 27 --> 10k --> DB9 Pin 7
Pin 28 --> 10k --> DB9 Pin 4
Pin 28 --> DB9 Pin 8

+5v and GND from USB

Pin 8 of PIC should be connected to ground.

[The_JinJ]

Wired like this:

Pin 1 --> 10k resistor --> Pin 20 VDD
Pin 20 --> 5V
Pin 19 --> GND --> DB9 Pin 5
Pin 26--> 10k --> DB9 Pin 3
Pin 27 --> 10k --> DB9 Pin 7
Pin 28 --> 10k --> DB9 Pin 4
Pin 28 --> DB9 Pin 8

+5v and GND from USB

Pin 8 of PIC should be connected to ground.

Yes sorry Pin 8 is to GND as well - can't figure out if this is a comms port issue or not (seems to read PIC ok, reads 00ffff)

[Firelord]

Yes sorry Pin 8 is to GND as well - can't figure out if this is a comms port issue or not (seems to read PIC ok, reads 00ffff)

It will read 0xffff words regardless (even if you physically remove the PIC from its socket).

[The_JinJ]

Yes sorry Pin 8 is to GND as well - can't figure out if this is a comms port issue or not (seems to read PIC ok, reads 00ffff)

It will read 0xffff words regardless (even if you physically remove the PIC from its socket).

If not connected or no power always seems to read all 0's for me - so I assume reading 00ffff it can at least see the chip (WinPic)

[Firelord]

Are you using WinPic800? I cannot tell whether it will make any difference or not, but try it. Choose JDM programmer from the options and also your COM port number.

[The_JinJ]

Are you using WinPic800? I cannot tell whether it will make any difference or not, but try it. Choose JDM programmer from the options and also your COM port number.

Thanks Firelord - tried them both - now tried low and high voltage (com84) programming with no joy - at a loss and this is with 2 seperate chips so doubt both are fried......

[The_JinJ]

Here is the breadboarded circuit - anyone any ideas why it doesn't work??



R1 - 10k
R2 - 10k
R3 - 10k
R4 - 10k
R5 - 100
C1 - 22uf
C1 - 22uf

USB holds a steady 5v even when programming
Pin 1 of PIC rises to 10.5v (which should be enough to enter HV programming mode)

[dmitri]

How did you come up with this schematic?
What are C1 and C2 (22uF!) doing on clock and data lines?


The ICSP cable and my programming instructions are based (carbon copied) on this simplified LVP programming cable: http://home.vrweb.de/~lotharstolz/stolz ... index.html

[The_JinJ]

How did you come up with this schematic?
What are C1 and C2 (22uF!) doing on clock and data lines?


The ICSP cable and my programming instructions are based (carbon copied) on this simplified LVP programming cable: http://home.vrweb.de/~lotharstolz/stolz ... index.html

The caps were suggestions from Microchip forums - I initially never had them

[dmitri]

The caps were suggestions from Microchip forums - I initially never had them

22uF?
to +5?
for PIC18F2550?