gnupic: PIC16F877
Subject:
Re: PIC16F877
From:
Ulrich Dziergwa ####@####.####
Date:
6 Jan 2003 19:27:02 -0000
Message-Id: <3E19D68A.701@web.de>
Philip Balister wrote:
> I am thinking about doing a project using a SMT 16F877 part. This means
> I need to program it in circuit. From a quick read, I believe it is
> possible to program this part after it is installed in the final
> circuit by correctly setting up four pins or so. And that there is
> Linux software available for this.
>
> Am I thinking correctly? Any gotchas to this approach?
>
> Philip
Hi Philip
I have done this with a 16F876, should be the same with the 877(a). For
programming and debugging with an ICD you need RB6 and RB7, a connection
to MCLR, to GND and to VCC. There are some app. notes how to use the two
port pins for both programming and as ports, but I used them only for
programming. To make the handling easier, I put an RJ11 socket on my
board and use a short strait thru cable to connect it with the ICD. If I
want to debug with MPLAB, I enable debugging and the debugging code is
automatically inserted by the programmer. When I'm finished with that (I
know, debugging is never finished) I program all the boards without
debugging support.
I have seen a design, where the two programm pins RB6 and RB7 share the
pins of a connector, which is used by an I2C bus. During programming the
I2C bus is never used and vice versa.
I would not recommend to put a PLCC device very often in and out of a
normal socket because leads are easy bent. The programming sockets for
PLCCs are realy expensive. If you must use the programming pins in your
design and the tricks for using for both don't work for you, you can use
a small double pole switch to isolate your application from the
programmer, but you will loose the debugging support, which is realy
similar to an ICE.
Regards Ulrich
