:o Got 3 PBC's made a few months ago and all 3 worked as intended so was very happy. Now going to have a go at something a bit more complex.
I've a lot of libraries I test and develop on my Arduino Due(s) and tbo... they're a pain to keep wiring up.
I've therefore started to design a shield that exposes all the pins but also has slots for some "standard devices".
I have a micro SD card reader off EBAY (CS SCK MOSI MISO VCC GND) along with a RTC unit (GND, VCC, SDA, SCL, SQW 32K) that I've provided slots for. If not using... simple leave the space empty.
Also... if another device has the same pin arrangement... just plug it straight in and make your drivers use it.
Another device provided for onboard is for SPI output device with (VCC, GND, DC, RST, SCK, MOSI, MISO)
Have also included interface to spansion/winbond Flash memory mounted on a DIP package. If need flash memory add a chip with compatible pinouts (8 leg variety seem to have a standard pinout) and use. The io0 - io3 pins are mapped to a pin such that the 4 bits can be get/set easily.
Other thing I've put in the initial bash is parallel port expansion. Basically the Due has pins 33-40 and 51-44 that map to continuous port addresses that have been broken out for easy use.
Have been thinking of even breaking them out to 9 bit to cater for some color displays that cater for 9 bit parallel for data as 33-41 and 51-43 are continuous.
Add header for OV7670 camera module so it can be just plugged in without 100000 wires to connect.
I want to also add a few general purpose SPI expansion headers so if another SPI device needs to be added already pins ready to use. Same goes for SDA and SCL.
ICSP ... I truly hate the ICSP and how it fits in with shields. I have opted to have a cutout around it and for a small jumper to be clipped onto it and the shield.
I'm still in 2 minds about how to connect the ICSP to the shield... as I only need MOSI MISO and SCK which are not (to my knowledge) on any of the other pins.
:o Executive decisions....
The aim of the board was to save wiring when adding a few "standard" devices" so things like SD card have their CS set to pin 4 which allows hardware SPI. SPI display has CS as 11 which allows for hardware SPI if wanted and DC set to 10.
I have another board that can be soldered on easily (top right) and has 2xmcp4921's and a PAM8403 amplifier.
Basically I want to utilise as much of the real estate as possible but making it so if something is not needed then that part of the board is just left.
Any thoughts, ideas, criticism, improvements welcome.