Want Help with Your chipKIT™︎ Pi? Get AnswersTom Devine Through Nov. 8th!

Hi

Will you be updating your quick start document as a result of interactions with Tom Devine? There has been so far a lack of any response from element14 to my 3 posts here and other posts in comments on the ChipKit Pi page.

Tony

Hi Tom,

Can you direct with any projects you have built?

What your experiance with those builds were?

Hi Tom

Thanks for replying. I'll summarise here in one email the problems which I encountered and some fixes. As I said above, there needs to be some extra info - I had no familiarity with Arduino, and I expect there will be a lot of customers for the Chipkit Pi who want to use it to discover the Arduino world as well as the Pi. Some of these were posted in the comments at the bottom of the element14 webpage announcing availability of the Chipkit Pi:

http://www.element14.com/community/docs/DOC-55170/l/microchip-the-latest-arduino-compatible-chipkit-pi-platform-for-raspberry-pi

1. Image file too big:

I found a problem with the NOOBS image as linked to in the above page - its too big for my 4GB card - writing from my Mac, I get this error:

dd: /dev/rdisk1: short write on character device

dd: /dev/rdisk1: Input/output error

3782+0 records in

3781+1 records out

3965190144 bytes transferred in 467.537095 secs (8481017 bytes/sec)

Then trying to boot this image on the Pi, we get a Kernel panic because the 'block count 644608  exceeds size of device (642432)'

and unknown block (179,6)

So it woud be good if you made it a slightly smaller image to fit on all SD cards (mine is a SanDisk Ultra 4GB 200X SDHC card).

Doing a repair on the Pi by holding the shift key down while booting gets the image repaired, but without the ChipKIT installation, so quite pointless!

2. Cant find java - since the above image was too big, I had to do it in stages:

Managed to download the mpide-0023-linux-20120903, onto my Pi which had java for armhf already installed. Also had to install librxtx-java.

Also had to add a path in the mpide bash script in order to find rxtxserial:

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/lib/jni

Then it sort of works when I type ./mpide from the mpide.... directory.

Can load and edit the sample sketches etc, but cannot compile due to a permission denied error.

Running mpide with sudo doesnt seem to be an option because it then cant find java.

3. Advice from David Burke about a later version of MPIDE:

Tony, I had more success with

mpide-0023-raspberrypi-20130817-test.tgz

unpacked into a local folder in the pi directory of the flash card, a later version methinks.

This compiled OK once MPIDE decided on the serial port, was trying for ttyS1 instead of ttyS0 even though I followed Ankur's Getting Started Guide.

When I tried to upload a compiled sketch ( blink demo ) I got the following error....

Binary sketch size: 5632 bytes (of a 122880 byte maximum)

avrdude: AVR Part "32MX250F128B" not found.

I thank you for your idea of exporting the LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/lib/jni idea, in the MPIDE start file, it worked well.

So now I need to know from Ankur what version of avrdude he is using, the current Raspbian one is version 5.11.1-1, or is there some configuration file that needs fiddling?

Close to working but not quite there.

4. Further progress:

Eventually found the latest MPIDE in a collection of XML structures on:

http://chipkit.s3.amazonaws.com/index.html

I downloaded and unarchived on my Pi. I added that export link to the mpide script, and all ran nicely from a debug window as before.

However, when I try and compile the Blink script I get exactly the same error - no errors in the debug window from java, but the following on the Blink | Mpide window:

Cannot run program "/home/pi/mpide-mpide-0023-raspberrypi-20130817-test/hardware/pic32-tools/bin/pic32-g++":error=13, Permission denied

found a blog with useful info, having Googled for parts of that error message:

http://colinharrington.net/blog/tag/microcontroller/

So following his advice, I changed the permissions on the pic32 folder.

Now the sketch compiles but then falls over at the size determining phase - java-io.IOException: Cannot run program "avr-size" error=2, No such file or directory0. This error also appears in the java debugging terminal window.

I have searched the Pi for avr-size, and it doesn't exist.

This post seems to have the answer to this:

http://www.chipkit.org/forum/viewtopic.php?f=6&t=90

Installed gcc-avr package (sudo apt-get install gcc-avr) - another 43.6MB of damn disc space used - annoying, because I like PICs and have steered away from AVR micros, so I didnt expect to have to download their library as well.

I selected the chipKIT UNO32 - not sure if that is right - doesnt seem to be a definiton for the Pi one.

Yippeee - that worked. Its very slow, though, to compile such a short program - mind you the size is pretty big as well - binary sketch size 5980 bytes.

Then I tried uploading the binary after putting the kit into load mode - no error, and some minute or so later it said it had Done uploading.

However resetting doesnt show a blinking LED - maybe have to study the circuit to see if the sketch is correct.

Getting there slowly and painfully.

5. Further help from David Burke for a yet newer version with the correct pic32 definitions. Also changing the a standard sketch to use the LEDs available on the Chipkit Pi:

mpide-0023-raspberrypi-20130920

this one has the correct avrdude configuration file for the PIC32 chip used, you still need to put in your startup link to the serial library. Obviously it is Year-Month-Day format.

I used the "blink without delay demo" but with the following tweak as pin-13 seems to have no LED on it, which is different to Arduino

// constants won't change. Used here to

// set pin numbers:

const int ledPin =  14;      // the number of the LED-1 pin

//const int ledPin =  15;      // the number of the LED-2 pin

I am using a fresh install on a RPI 512 V2 with the new Raspbian Image with a 16GB flash card.

The demo now uploads and works as advertised!     

6. Missing definitions in the pic32 libraries comapred with the latest Arduino UNO libraries:

I am trying to compile an Arduino skech that uses some extensions which dont seem to be present in the chipkit pic32 libraries:

these are used with "Serial" and are "parseFloat", "parseInt" and "setTimeout".

Does anyone know how to get these library additions, or is there some more simple code to perform them?

later addition - am looking presently at the source code in the Arduino libraries to code these functions at a lower level for the pic32/

7. More pinout stuff - probably largely due to unfamiliarity with Arduino:

Has anyone had any success understanding the Arduino-like pin numbering system for the ChipKit Pi pic-32 board? I have so far established that LED1 is 14 in a Sketch, and LED2 is 15. These are correctly labelled in the middle column of the table on the pin-out map in the quick start guide (as 14/A0 and 15/A1). I am presently trying to find which pin numbers are used for the Tx Rx LEDs, but the circuit and tables are so full of errors that it is proving impossible. So far I have tried 4 and 5, and 11 and 12 (from the table), and neither pair work. Next stop is 0 and 1 (from the JA2 SCOKET (sic) diagram).

It takes so long to compile and upload on the Pi, that experiments tend to take forever. Ah, the last sketch just compiled, so I am waiting for the upload to complete - aha - success - it is 0 and 1.

So it looks like the "SCOKET" pins are numbered correctly, as per an Arduino. - thats the Green numbers to the right of JA1 and JA2. I havn't gone round the oins yet with a meter - only watched the LEDs so far.

Anyway - looks like I am answering my own post as a write it, but any other comments are welcomed.

8. Make sure the correct serial port is defined in the code so it talks to the Pi:

Got the Dallas One Wire code working on pin D2 of the ChipKit Pi (third from right at top) having changed from the program default pin 10 which is not 5V compliant. Actually a DS18B20 sensor works OK with a 4.7K resistor to +3.3V as well as 5V. Be aware, that the serial communication port has to be changed from Serial to Serial1 in order to talk to the Pi using the same UART connections as for uploading the sketch. This needs adding to the Quickstart document. I only found this out by experiment.

That about summarises it all for now

Tony

Hi Tony

Thanks for the reply. That is all some real great information. I have not tried loading from a Mac. Only a PC so I cant offer any advice or guidance. Can any members out there offer any advice or experience relevant for a Mac (or any other device for that matter)?

Regards,

Tom

Hey Eric, I noticed that you had question that I’d be happy to try and answer for you.

You asked;

<Can you please indicate the advantages using this board versus building a direct communication between Ras-PI GPIO and ChipKit Uno via I2C or USART?> 

on the discussion thread: http://www.element14.com/community/community/knode/dev_platforms_kits/element14_dev_kits/microchip-chipkit/chipkit_pi/blog/2013/09/16/chipkit-pi-the-technicals#comment-26969

I think the main advantage of the chipKIT-Pi is usability. I think this expansion was designed for the beginner level hobbyist in mind or a hobbyist looking for a quick and easy way to integrate a microchip board to the Raspberry Pi. With that being said I have found that introducing some Python-based communication from the Raspberry Pi rather interesting. I have found an example here for you if you are interested.

http://chipkit.net/motor-control-raspberry-pi-chipkit-pi-arduino-motor-control-shield/

Warm Regards,

Tom

Hello Everyone!

Anybody out there interested in sharing their knowledge of the the chipKIT-Pi? I would really like to hear about your experiences from both ends of the spectrum..

-Tom

hi tom,

        I have chipKIT UNO 32 is it possible to interface it with my RPi (through USB)

Yogeswaran,

Hi! Great question! My answer is yes; just choose your board under the tools menu. Also, I would recommend a powered usb or some sort of separate power between the pi and whatever board you might use as the raspberry pi does not have efficient power to run both.

-Tom