Re: PLC software
- From: Peter Bennett <peterbb@xxxxxxxxxxxxxxxxx>
- Date: Fri, 08 Sep 2006 19:30:45 -0700
On Fri, 08 Sep 2006 01:13:33 GMT, "sjb" <sjb@xxxxxxxxxxxxxx> wrote:
Hi all,
Well, I'm on my way to making a career change back into electronics. Been
out for a while, but I'm currently brushing back up on my digital
fundamentals, with the intent on learning PIC's, MPU's, etc. in the near
future. What I've been seeing out there is confusing the heck out of me.
While I have a vague idea about what's going on with PIC's, my question is
this:
The term "PIC" as used in this newsgroup refers to a family of
microcontrollers manufactured by Microchip.
An MPU is, to me, a microprocessor - the heart of any computing system
- built on a single integrated circuit. (When I started in this
business, a CPU or MPU would occupy a 15" x 15" printed circuit
board.) An MPU or CPU requires program and data memory and I/O
devices to make a useful computer.
A microcontroller is a single integrated circuit that contains a CPU,
program and data memory, and I/O devices.
When programming PIC's (VHDL, CPLD, FPGA's, or for that matter MPU's...) is
VHDL is a programming language used in preparing configuration files
for CPLDs (Complex Programmable Logic Devices) or FPGAs (Field
Programmable Gate Arrays). CPLDs and FPGAs are ICs that contain logic
gates, flip-flops, etc, that the user can interconnect in various ways
- the interconnection may be specified using VHDL, AHDL (Altera's
version of VHDL), or by drawing schematic diagrams.
there a "standard" software that one can use on all of them? Or, is each
chip manufacturer specific as to what software you have to use to accomplish
the tasks?
For CPLDs and FPGAs, you usually have to use the manufacturer's tools.
For example, could I use my old Borland C (Ver 3.21) to write
code, compile, and then assemble it using the Turbo Assembler (TC), then
load it onto a chip? Or, for that matter, just write assembly code with the
TC and expect to be able to load it to a chip?
No. Borland C will produce machine language code that will run on
8086-compatible processors. Each microprocessor or microcontroller
family will use its own machine language, so you will have to use a
cross-compiler or cross-assembler that will produce code for the
processor you wish to use. (A cross-compiler runs on one processor,
such as your PC, and produces code for some other processor, such as
your 68HC11.)
The C language is often described as "portable", meaning that the C
source for a program can be compiled to run on many different
processors - unfortunately any useful program will have many things
that are dependent on a particular operating system (or, particularly
with microcontrollers) the specific hardware, so the program probably
won't run on another system without a significant re-write.
I have an M68HC11 MPU that looks like there are several options for
generating code. They mention "resident language support" for Forth?, Basic
interpreter on EPROM, Small C compiler, and Assembler. I thought these would
be programs that one would use to write code. What do they mean resident on
the chip? I'm hearing talk of Boot Loaders, etc.
I just thought that one would be able to write a program, assemble it, and
then load it.
Arrrrghhhh~!
If anyone can set me straight, and put it in a nutshell, it'd be much
appreciated.
Scott
--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
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