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Want Help with Your chipKIT™︎ Pi? I’m a Microchip design partner!  I’m here to help Nov. 1 - 15th!

kmansfie
Hi, I’m Kim Mansfield.
 
I have been working with microcontrollers for over 30 years. I hold degrees in computer engineering from the University of Utah and Utah State University. I have gone through the typical corporate jobs working for Sperry Univac (Unisys), Novell, and other company's you probably haven't heard of.  I'm now a contract engineer and work on a lot of different things.
 
I have been watching the Arduino grow and develop.  I have done a little work with the Arduino and have found that the development environment is easy to learn especially for me.  I program almost exclusively in C.  The Arduino IDE's language is very close C.  As you know I'm a Microchip Design partner and know a fair amount about the processors Microchip produces.  I thought it would be great to have a similar ease of development for the Microchip product line.  I then found the chipKIT boards.  I really liked the idea.  I jumped in very early in the development of the chipKIT IDE.  There were problems and some incompatibility between the Arduino and the chipKIT.  Software written on an Arduino come close to running on the chipKIT without modification but usually there needs to be some changes.  The biggest difference between the Arduino and the chipKIT boards is the chipKIT boards are 3.3 volt based and the Arduino is 5 volt based.  But, the people at Digilent have done an excellent job with the chipKIT IDE.
 
I have designed several products using chipKIT boards.  I designed a system that interfaced to a WiFi network to report status on a remote irrigation pump.  This included a screen to show the status locally.  With my introduction to the Raspberry Pi, I might have used that instead of the chipKIT.  The Linux operating system has a little better support for the network portion.
 
When I was contacted by Lauren at element14 about helping out here I had never heard of the chipKITTm Pi.  I knew what a Raspberry Pi was and what a chipKIT was but the combination?  I found out that they have designed a board that plugs right into a Raspberry Pi.  It sounded interesting.  I received my Raspberry Pi and chipKIT Pi about a month ago and have found it to be a great combination.  I received a case for the Raspberry Pi as I wanted to protect the board.  But, I found that I couldn't use the case that was sent as it didn't expose the I/O connector of the Raspberry Pi.  I went online and found a case called a Pi Tin.  It comes in many colors including clear which is the one I opted for.  The Pi Tin has a cut out for the I/O connector allowing the chipKIT Pi to be plugged into the Raspberry Pi and still protects the Raspberry Pi.  It works well.
 
image
This is a picture of the Pi Tin with a Raspberry Pi in it.  You can see the I/O connector in the upper left which is exposed.
image
This picture shows the chipKITTm Pi plugged into the Raspberry Pi.
 
I went through the getting started document on Element 14.  After I finished with that my Raspberry Pi booted and had the chipKIT IDE on the desktop.  I opened the IDE and wrote an LED blink program, programmed the chipKITTm Pi and it worked.  I was impressed at how easy the chipKITTm Pi was to get to work.  The board seems to be well made and integrates with the Raspberry Pi well.  The 28 pin Microchip chosen is nice as it allows you to take the part out of the board and plug it into a bread board to experiment with the chipKITTm Pi without the Raspberry Pi.  This 28 pin part also has a down side.  The lack of I/O pins.  It is very limited in the number of pins you have access to.
 
I suggest that if you are interested in interfacing to your Raspberry Pi this is a great way to do it.  Buy a board and dive in.
 
You can find some of my other projects at http://www.theengineertutor.com/
 
I welcome hearing any questions, comments or experiences you have about working with the chipKITTm Pi and its technology. Ask (or tell) away!
 
Kim
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  • in reply to bad_boy_y

    Hi,

     

    I reviewed the schematics and I believe the chipKIT Pi could be used for an RTC for the Raspberry Pi.  You would have to stuff the battery as you mentioned and I would also recommend stuffing the 32khz crystal which can be used to drive the RTC inside the chipKIT Pi for more accuracy.

     

    Kim

    http://www.theengineertutor.com/

  • in reply to kmansfie

    I have been working with the chipKIT Pi for a little while now and thought I would give you a little tour of this great device and mention a few things I think it would be good for.  The chipKIT Pi is based on the chipKIT boards made by Digilent.  These boards are Arduino compatible.  That is to say they use a similar IDE as the Arduino which is called MPIDE.  You can down load this software free from Digilent.

     

    If you aren't familiar with the Arduino IDE there are lots of places where you can get help with the environment.  Here on Element 14 the The specified item was not found. area would be a good place to start.  Another resource would be the Digilent site that contains a lot of interesting code examples and tutorials as well as the MPIDE software.

     

    The chipKIT Pi communicates with the Raspberry Pi over a serial link.  The chipKIT Pi uses pins P11 and P12 for the serial link from the Raspberry Pi as well as 5 volts, ground, and reset.  The rest of the pins on the Raspberry Pi connector are routed to the Raspberry Pi connector on the chipKIT Pi.  This gives you external access to most of the pins on the Raspberry Pi even if the chipKIT Pi is plugged in.

     

    On top of the chipKIT Pi you have standard Arduino connectors.  Not all the pins on the Arduino connector are active.  The pins AREF, D7, D6, D5, D4, A2, and A3 are not connected on the chipKIT Pi.  The rest of the pins are connected and function similarly to the Arduino.

     

    You maybe saying but, what is it good for?  That is a very good question.  I have worked with Unix/Linux for many years and I know that sometimes the interrupt response times of these systems can be a little on the slow side.  The chipKIT Pi would work very well in a situation where interrupts need quick response.

     

    Another good use for this board would be in assisting the Raspberry Pi in a hardware intense situation like controlling the brightness of an LED or the speed of a motor.  The chipKIT has two dedicated hardware PWM channels as well as RS232, I2C and SPI buses.  Any of these peripherals could help your Raspberry Pi out.

     

    There is another bonus to the chipKIT Pi.  It has 3 5V tolerant pins (D12, D10, and D2) that you can access.  This will save your sensitive Raspberry Pi from damage.  I see in the forums over and over again warnings about the Raspberry Pi I/O not being 5V tolerant.

     

    The PIC on the chipKIT Pi has a really fast 2 channel 10 bit ADC in it.  The data sheet says that it can do 1Msps.  This would make a good input for an oscilloscope.

     

    Another thing I thought of using the chipKIT Pi for would be to handle a wireless link.  The wireless link wouldn't be a WiFi link but a custom link of wireless sensors.  I have been working on such a project.  You can see that project at my site (http://theengineertutor.com/).  I have been etching my own boards and using Eagle to design the boards.  I currently have 5 nodes up and running reporting temperature from various places in my yard and house.  In this case the chipKIT Pi is handling the wireless link and all of the protocol from the sensors.  The Raspberry Pi only receives good packets.  This can free the Raspberry Pi to do other important things.

     

    These are just some of the things a chipKIT Pi would be good for.  I'm sure there are many other uses that you can think of.

     

    Kim

    (http://theengineertutor.com/)