Hello all,

I'm trying to figure out how to setup an SPI connection between the Overo Summit (with the Overo Fire) and my external hardware using Python.

I've asked this question already and got some pretty useful answers, but they all referred to development in C... the thing is, I already have some code to do other stuff in Python, so I'm looking to stick with Python and continue the development to communicate with my external hardware... can anyone help me out with this?

I have the hardware all wired up, but I'm not sure where to start on the software side. Any help is very very much appreciated!
Thank you!!

Shane Frasier wrote:
The Python serial terminal program miniterm.py will help you get started using pyserial:
https://trac.cs.earlham.edu/ecoi/browser/serial/pyserial-2.2/examples/miniterm.py

If you need to create your own serial protocol, the easiest way is to use a character you will never actually have in your data to denote the start of a new packet.  Then write your packet data and follow it up with a second character that will never appear in your data.  Finish up with a checksum so you can do some error checking.  Look at some NMEA sentences to help you get started.
http://www.gpsinformation.org/dale/nmea.htm

For example, in the NMEA sentence
$GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47
The "$" denotes the start of a new packet, GPGGA denotes the type of packet, then the data follows.  The "*" character tells you that the data portion of the packet has completed, and "47" is the checksum for this particular packet.

If you want you could do away with the "end of packet" character and follow the "beginning of packet character" with the packet length instead.

If your data can contain any character, including the "beginning of packet" character, then you will have to escape the beginning of packet character when it appears in your data.

Shane
-----------------------------------
Shane Frasier
shane.frasier@gmail.com



On Jul 6, 2010, at 4:33 PM, Mannissa Chang wrote:

Hi Shane,

Thanks for responding... can you point me to any references on where to begin with this? or describe which serial protocol you used and how to go about setting this up? I haven't done much with serial interfacing before...

Thanks so much!

Shane Frasier wrote:
I've had no problems with the Overo Air and the Palo43 expansion board.  But the serial port runs at 1.8 V, so you may need a level shifter.

Shane
-----------------------------------
Shane Frasier
shane.frasier@gmail.com



On Jul 1, 2010, at 3:42 AM, Mohamad Najib wrote:

  
    
...
      
Has anyone had any luck with implementing a serial connection using 
Python?? I have an Overo Fire with the Summit board.
        
...

      
Using Overo Water with the Chestnut expansion, and I have been successful in
using the serial port on the 40pin header with Python (with the help of
pySerial)

Using Pin 9 (GPIO151_RXD1) and pin 10 (GPIO158_TXD1) for it, with a
precompiled image.

Regards,
Mohamad Najib
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