Desire for small Pic32 board for Robots...

Created Fri, 16 Mar 2012 15:21:10 +0000 by KurtE

KurtE

Fri, 16 Mar 2012 15:21:10 +0000

Over the last year or so, I have been playing around with different processors to use to control some of my robots, which use the Lynxmotion servo erector set...

I have a Chipkit UNO32, which is a great little board and I have the Phoenix Hexapod code ported over to this and it works fine. I am still using an SSC-32 board to handle the servos, as it was on the robot and the UNO32 is not setup to handle the servos. I would very much like a chipkit like board that was setup to handle servos. In addition, I can never get enough USARTS :lol: So it would be great if it used one of the Pic32mx series that had more than 2. So for the fun of it I started designing my own... [attachment=1]DipTrace-PCB---BBPic.jpg[/attachment]

But, I decided that this is beyond my soldering skills, so I backed off a bit for now, and designed a shield, that has the Arduino Mega form factor, which I will try out, with Arduino Mega and Chipkit Max32. I am having a couple of these fabricated and should get them next week. Will take me awhile to solder them, but should be fun. [attachment=0]DipTrace-PCB---Arduino-Mega.jpg[/attachment] There is more details about the shield up on the Lynxmotion forum thread: http://www.lynxmotion.net/viewtopic.php?f=26&t=8021

But, I still wish someone would build a one board solution, that is small and compact.

Kurt

Ryan K

Tue, 20 Mar 2012 21:41:38 +0000

Hello Kurt,

This is probably too big but I decided to just let you know about it anyways. :) Digilent has the Cerebot MX4ck that has 2 UARTs and 8 servo connectors. It is approx. the size of the two chipkit Max32 next to each other.

http://digilentinc.com/Products/Detail.cfm?NavPath=2,396,985&Prod=CEREBOT-MX4CK

Best Regards, Ryan K

KurtE

Tue, 20 Mar 2012 23:43:47 +0000

Thanks Ryan, But my Hexapods have 18 or 24 servos on them, so the 8 servos won't quite do :)

My boards from PCBFabexpress for a shield for either Arduino Max or or the Max32, should arrive tomorrow. The parts to populate a few of them have already arrived from Sparkfun and Digikey, so I am looking forward to being busy with a soldering iron for several hours.

If it all works out, the Shield will give me: 48 Servo like connections (including the 16 analog pins). You can choose the voltages (either the input voltage or +5v) for each group of 4 pins.

In addition it has connectors for the 4 USARTs, They are in the order that I can simply take a servo extension wire and connect it directly to a Lynxmotion SSC-32 board...

Also has a small speaker (like the Lynxmotion Bot Board 2) 3 buttons 4 LEDS including the standard one on 13. And connectors to plug in an XBEE which I have hard wired to USART3.

Should be fun. But I still wish some one would build a single board with type of functionality (maybe something like a Basic Micro Arc32), with a small foot print. Compatibility with shields would not be a high priority.

MY number of IO pins is probably overkill, but this way I probably won't run out.

Kurt

KurtE

Sat, 24 Mar 2012 23:00:35 +0000

FYI - I received the 5 boards back from PCBFabexpress for my Shield and I have assembled one of them:

[attachment=0]Mega-Shield.jpg[/attachment]

So far my testing is going well. I have verified that the buttons, LEDs and speaker are working. Likewise the PS2 is working and I can talk to my I2c EEPRom.

I have also verified the grounds are connected properly and I can choose the proper voltages for each 4 IO pins.

A few differences I noticed versus some previous testing the Analog pins on an Arduino. The reference voltage is 3.3v vs 5v. For me that is not an issue for testing the VS and VIN voltages as I use a 4 to 1 voltage divider, however this could be an issue if I go more than 12v... Also noticed that when I am running the Max32 off of USB and had no other external power connected, VIN was 0, whereas on some Arduino Megas I have tested with, it was the voltage of the USB.

Next up is to test the XBee or write my oven version of the Servo library.

Kurt