gnupic: Re: [gnupic] PIC under Linux developpement Howto
Subject:
Re: [gnupic] PIC under Linux developpement Howto
From:
David McNab ####@####.####
Date:
5 Jul 2005 04:08:47 +0100
Message-Id: <42C9F9B3.90509@rebirthing.co.nz>
Christopher Bergeron wrote:
> I'm going to have to second this one. However, there's a part of me
> that thinks that having choices will be confusing to newbies.
Well. in the light of all this reaction, allow me to amend my original
suggestions:
* C is most useful IMHO - more useful than dumbed-down high-level langs
like BASIC, and less annoying for the newcomer than assembler, and
easy to interface with assembler
* another alternative is PyAstra - a cut-down Python to PIC assembler
compiler - but Python scares many folks because whitespace is
syntactically significant, so should probably stick with C instead
* assembler is menial - justified only when performance or environment
limitations necessitate it - you get way more functionality per litre
of blood/sweat/tears when programming in higher level languages,
because it's way easier to concentrate on the 'what' without being
constantly distracted by the 'how' - basic stuff like parameter
passing, data structures, and (in the 16F case) those damn fragmented
program/data memory segments etc etc - C compilers spare the user of
all that crap
* a howto should take the user, step by manageable and verifiable
step, from a bag of parts and an internet connection through to a
board with a blinking 'hello world' LED, and then through to other
PIC stuff like ADC, PWM, USART etc - without them needing to spend
a cent on anything other than hardware
* I'd suggest sdcc - it's not the prettiest C compiler, but it can
do the simple stuff, and it's speech/beer free, and available on
all decent linux distros
* I'd suggest the 16F876/7 as the main chip, since it can self-program,
it has the on-chip goodies, and it's cheaper than the 18Fs; upgrading
from 16F to 18F is orders of magnitude easier than the other way
round; also it's got less memory scarcity than (say) the 16f873
* for a programmer - probably best to pick one that:
- has minimal parts count
- can work via serial port (PCs usually have 2 serial ports but only
one parallel port, and the parport is often in use with a printer)
- has PCB artwork and parts list, plus working Linux-compatible
on-chip and on-host programming software, freely downloadable from
the net (I bought a great programmer kit from Jaycar, but can't
recommend this because Jaycar only has stores in Aus and NZ, and
this would be a pain for people in other countries)
* for a bootloader - I'm personally using TinyPIC Bootloader on my
18Fs, but haven't got this working on the 16Fs (so I use the PicForth
Serial Monitor on those chips) - need to choose a bootloader which:
- is written in assembler and builds ok on gputils, or is written in
C and builds ok with sdcc
- has a working host client written in a common language, that is
easily built with reliable results without dragging the user
through autocrap/dependency hell (as linux progs can sometimes do)
* tutorial should include a section on gpsim, using .map and .lst files
so user can correlate the high-level code to the raw binary; should
walk user through:
- setting up gpsim config
- single-stepping and use of breakpoints
- inspecting SFRs and user data memory contents
This approach eliminates the complication of multiple
chips/languages/programmers.
--
Cheers
David
