William Chops Westfield wrote:

>
> On May 14, 2005, at 2:18 PM, David P Harris wrote:
>
> Zonker?  Or some other David Harris?
>
>> I am nearly out of PIC based the 24 OmniPort PCB boards I had made (I
>> have a few left for me). However, this represents a great opportunity
>> for me to correct the mistakes on the board, and perhaps do some
>> redesign, before I order some more.
>>
> You sure have a lot crammed onto that board...

Ahh, yeah :-) :-) ;-)

>
> What are the mistakes that you hope to correct?

Oh, nothing too major.  Some of the pin choices might have been better.  
Some of the parts' holes could be slightly bigger.  I have put on places 
for RS232 and RS245 drivers, but you can't use them both at once (well 
not with the USART).  I should not have connected them the PIC (a small 
jumper cable would have been more flexible), or at least made it easier 
to disconnect the traces.  The model railroading community would 
probably like RJ45 connectors on board as they are standard for one of 
the bigger manufacturers, and there are third party PD projects that are 
compatible with my board. 

I am generally happy with it.  I am quite proud of the output/driver end 
of things, it allows a multitude of connectors/output options.  You can 
directly connect servos, LEDs, pull-ups or pull-downs.  The PIC pins are 
protected with 330 ohm resistors.  Easy to put in pin headers with pin 
jumpers for option selection.  You can have moderate current outputs via 
ULN2803 or ULN2981, or high current outputs with Darlingtons or 
Mosfets.  I like to use mini screw 0.1" terminals from Phoenix 
Terminals, but you can also use pin headers, sockets, SIL or DIL. 

Of interest, the opamp layout is very general, but the components all 
mount vertically, and its cramped. 

Still for building little projects quickly, its great :-)

David
PS- the AVR one is almost identical but it uses a Atmel ATMega8, I 
screwed up the eeprom wiring on it, so its less flexible (the PIC one 
allows I2C or SPI).


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