PIC proto/breakout board

[Mosaic]

Hi all:
I've decided to make my own proto/breakout board that plugs into a breadboard for prototyping pics from 6 pin thru 40 pin DIPs

I figure that a crystal isn't that necessary anymore as most modern pics have flexible units built in which permits s'ware controlled clocking.
I expect to provide both 5V and 3.3V as well as a 0.1% precision Vref (adjustable), a 4 digit 7 segment display and a few buttons & LEDS and a beeper.
All 40 pins (via a bottom hdr) will connect to the breadboard and a matching top mounted hdr will connect to my Rigol Logic scope for debugging.
The board will permit up to 3 independent pics (totaling <40 pins) to be operating simultaneously. Optionally Opamps can be used side by side with smaller than 40pin PICS.
The board will have inbuilt jumpering for all pins to permit reordering the way the pins come out to the headers for simpler breadboarding.
A jumpered ICSP header is present as well.

I am hoping for any comments b4 I commit to build.
Most proto boards I have seen cater for crystals (I've never had to use one) and just a few PIC sizes, with only one in action at a time.
If it goes well I can post it as a project here on ETO.

thx.

 

[pixman]

Instead of 7 segment display why not use an LCD.

 

[Mosaic]

LCD is a bit easier to attach to the breadboard, not needing CC driver transistors or dropping resistors. Less pins as well in 4 bit mode.

edit: pcb LAYOUT DONE , DBLSIDED 4"X6"

 

[dr pepper]

A jumpered icsp is usefull.

 

[Mosaic]

I'm implementing the pin jumpering using tooled IC sockets and CAT5e solid #24AWG wiring. The opposing jumper IC socket pins have a PCB 'solder jumper' feature to enable permanent one to one (wire free) jumpering, which will be the most common method.
The solder jumpers can be left open to permit inserting a through hole component 'into' the GPIO lines or to permit rerouting the GPIO, via the jumper IC sockets.

I decided to implement the PCB routing for a crystal&caps and bypass/decoupling caps for 40Pin PICS as protoboard pin jumpering is limited with this wide PIC as it 'bridges' half of the adjacent IC socket jumper pins. These parts are optional, but the enhanced protoboard jumpering capability for the narrow PICs pins can configure the protoboard to use these components with those PICs as well.
This will take advantage of the 4x PLL clock of the more modern PIC chips. It adds flexibility, although attention must be paid to the jumpering for all to work, but then that applies to any breadboard anyway.

I attach a PCB layout. The top layer is a ground layer that is left out for visibility.
There are 6 x 20 pin IC sockets ganged to permit any size PIC as well as offer the mentioned pin jumpering capability. This allows for 100% PIC pin isolation. Thus several PICS can be used at once with several jumpered power lines and GPIO being brought out to the twin 40 pin edge headers for breadboard connection AND simultaneous multichannel logic monitoring. No more tiny pin grabbing logic probe rat nest. The 20 pin socket in the lower left offers 3 x gnd & 3 x 5V and 2 x 3.3V pins for jumpering to the PIC jumper sockets. The top 8 pin jumper socket passes any 7 segment patterns to the anodes via a 220 ohm DIL array.
3 LEDs and 3 tactile buttons with weak pull ups are implemented as shown. I'll fully comment the PCB for user clarity later on.

 

[Mosaic]

I added a microSD socket and jumpers. I see these still factor as optional MCU breakout boards etc. and I have a few 1 gigs laying about.

 

[ClydeCrashKop]

These 40 Pin ZIF Sockets are still available at $1.95 each in quantities of 10 or more.
https://www.mpja.com/40-Pin-ZIF-Socket-6-Wide-ICs/productinfo/31451%20IS
(No connection, I just like this store and its in my neighborhood)

 

[Mosaic]

Good price but unsuitable for .3" wide DIL.
I have a couple ZIF but I find tooled sockets seem less noisy.

Since a breakout for prototyping means you'd not be swapping ICs too often I expect the tooled sockets to work ok, worst case is you replace a low cost socket a year or two down the road. An IC tester or curve tracer etc definitely requires a ZIF.

Anyway i added an I2C 24C512 chip into the design and the board is populated enough now.
I'll prob make it tonite.