Over the last many months, I have had the fun of experimenting with several different Micro-controllers and having a lot of fun. This included the fun with experimenting with a shield for the Arduino Mega, that was built to plug into the Seeeduino Mega. I like this board as it is compact and not that different in size to the normal Lynxmotion boards. I have also experimented with the Chipkit boards which are based on an 80mhz 32 bit Pic32MX processor. The boards and IDE make them reasonably compatible with the Arduinos. Also hopefully soon Arduino will release the Arduino Due, which is a 96mhz 32 bit ARM processor. Both of these platforms are based on the Arduino Mega footprint... I think it would be a lot of fun to try out several of my robots on these newer platforms, so I thought it would be nice to have a shield that had all of the things I needed and that I could plug into these boards. Note: personally I am not that big into shields, and wish there were boards that had the basic functionality that I want, but when in Rome...
So I started to play around with some of the different CAD programs out there. I tried both Eagle and Diptrace and found that I personally prefer Diptrace. What I came up with was a board that had 3 out of 4 mounting holes that match up with the Standard Lynxmotion boards. The fourth one ran into IO pins. Also have standard Arduiono Mega holes. The board is larger than standard Lynxmotion boards, but for the majority of my robots that should not be an issue.
The current Schematic looks like:
Kurts-Arduino-Mega-Shield-w.jpg [ 69.91 KiB | Viewed 2641 times ]
My current layout looks like:
DipTrace-PCB---Arduino-Mega.jpg [ 129.96 KiB | Viewed 2641 times ]
As you can probably see, I have this board pretty full of stuff. The biggest challenge was to leave enough room free to allow for an XBee.
I believe this design gives me:
32 Digital IO pins with 3 pin headers- that you can choose VS/+5V on groups of 4 pins. 1 group has PU resistors for PS2
16 Analog pins with 3 pin headers - Again can choose vs/+5V on each 4 pin group. (Pins can be used for digital as well)
4 leds (D13 + 3 others)
XBee: Setup to do voltage conversions - Need to verify I did this correct. I have this default through shunts to use USART 3
I2C EEPROM - Added the eeprom plus PU resistors.
I probably need to make another pass through and verify that I got all of the locations of things correct and then I will probably have a few of these boards fabricated for me. Will try the first one out with an older Arduino Mega I have sitting around, then I will try it out with the Chipkit Max32.