Build or Buy?

[n.mulvana]

On Tue, 15 Aug 1995, Danny Wallace wrote:

> Hi all,
> Please excuse if this has been discussed - just point me to the
> archives.
> I'm in the early stages of my EFI project and am trying to decide
> whether to start completely from scratch with cct design and
> board layout OR buy a commercial microController card - probably
> using a 8051.
Hi,
I have been involved in a EFI related project using the 8051 family of 
microcontrollers which I started from scratch so I thought I would just put 
my two pennyworth in.
my project was actually a fuel computer but some points are relevant!
It all depends on how 'deep' you are prepared to go with the project as 
to whether you buy commercial units or not, there is agreat sense of 
achievement to be had in designing from the ground upwards, but if most 
of your experience is in software programming with little hardware design 
you will probably be better buying a commercial unit.
 > Does anybody have any suggestions or warnings about 
trying to
> build from scratch.  Is it a waste of time?  I've never layed out
> a micro processor/controller board so am not sure if the layout
> will be so critical that timings etc will be a nightmare?  If
in my opinion it is not a waste of time but if you have not done it 
before,it is quite task to produce a board for a large project, you could 
cut quite a lot of the hard work out by using a chip with built-in A to D
such as the philips 80C552 or the one I used was the siemens 80C537,
the layout should not be too critical - try to keep the crystal and 
associated capacitors close to the microcontroller and use plenty of 
decoupling on addressing chips etc.,
 > anybody has done their own PC board - 
what method did you 
use - > photographic, just provide the layout to a commercial firm (this
> seems expensive for prototypes or one offs).  Any thoughts most
> appreciated..
I made my own PC board using a CAD package and some photgraphic 
equipment but I am in the
fortunate position that we make PCB's at work - the only thing I can 
suggest is to talk to local schools/colleges/universitys and ask if the 
have the equipment to produce a one-off PCB (for a small fee that is)
as you are correct in stating a commercial firm would be very expensive 
for a one off.
hope this helps in some way if you need any more info regarding the above 
points feel free to email me. 


> Danny
> Perth, Western Australia
> wallad at devetwa.edu.au
> 
>