Hi Mannissa,

I used pins 9 and 10 (GPIO148 and GPIO151) on the 40-pin header, together with pin 15 as the ground.  Those three wires are all you need for a simple 3-wire RS232 serial port.  But note that it uses 1.8V logic, so you need a level shifter to connect to a regular computer.  I tested by connecting to another Palo43, but you could also connect pins 9 and 10 to make a loopback serial port if you just want to verify that you're able to talk to it.

The linux device using those three wires is /dev/ttyS0 (I think - it's definitely one of the /dev/ttyS[0-3] devices).  You can connect to it using the minicom.py python script.

Not sure about the SPI bus.  I'm not even sure what linux driver is used, since it was built into the Gumstix kernel already and I didn't have to add it.

Let me know if I'm not answering your questions and I can explain more.

Shane
-----------------------------------
Shane Frasier



On Jul 10, 2010, at 11:30 AM, Mannissa Chang wrote:


Is this using the SPI interface?? And what about the physical pin connections to the 40-pin header on the Gumstix summit?
Reference: http://www.gumstix.net/Hardware/view/I/O-connectors-cabling/Gumstix-Summit-board-40-pin-header-SV1/112.html

Please help asap, any help is much appreciated! Thanks!!

On Thu, Jul 8, 2010 at 10:47 AM, Shane Frasier <shane.frasier@gmail.com> wrote:
The Python serial terminal program miniterm.py will help you get started using pyserial:

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.

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



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
-- 
View this message in context: http://old.nabble.com/Overo-Fire-with-Python-and-Serial-tp29040919p29042828.html
Sent from the Gumstix mailing list archive at Nabble.com.


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