In circuit flash programming

[GJB]

There comes a time when it is quicker to upgrade your application software without removing the PIC from the target hardware, or it may be you have chosen a surface mount PIC.

You can flash program your target device whilst it is in circuit using your Matrix Multimedia development board as a programming agent.

In your [b]application[/b] circuit you will need to bring RB6, RB7, MCLR, Ground & +5v to a strip connector.

On the strip connector, link the 5 pins of the strip connector to the ports named above to your application PIC, and also link the +5V via a 10K resistor and diode (cathode to MCLR) to the MCLR pin.

So in your pcb layout you have your application circuit with a strip connector and diode resistor as described above added.

On your Matrix development board, make sure there are no PICs mounted and plug in a header into one of the PIC sockets, (I used the 18 way socket) and make an extension lead with +5V, Ground, RB6, RB7, and MCLR wired to a suitable connector to connect with your strip connector on your application circuit.

To use, without applying power to your application board, connect the Matrix board via the extension lead you have made into the strip connector. The application PIC will draw its power from the Matrix board. Now follow the normal “Compile to Chip” procedure to program the application PIC.

Please note this will not work if RB6 or RB7 are connected and pulled down/up by your other application components in your application circuit, and if there is a PIC device plugged into the Matrix board.

[Benj]

Thanks for the info GJB, a great way to do ICSP from the Dev and Multiprogrammer boards.

[Mark]

This topic has been gone through in detail in the E-Blocks forum, dated 7 January 2007 ('Flying leads').

There are issues that arise from having MCLR pull ups on both the PCB and the programmer board and the technique can give rise to some obscure problems, so proceed with caution.

Mark