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Alpha Clock Five and serial in Python from a Raspberry Pi

edited February 2013 in Clock Kits
I am attempting to send serial data to an Alpha Clock Five from a Python script running on a Raspberry Pi. I have version 1 hardware, but I have updated it first to stock version 2 firmware and now GPS with the AdaFruit GPS module. I will admit that I am new to Python programming. I was able to use the same cable to upgrade the firmware and run the Processing demos from a Windows PC. The code I have written in Python so far is below. The code runs and the clock resets with no change in brightness...

# Rolf Mikkelson. 27-FEB-2013
import serial
header = chr(0xFF)
# print "header = ", header
# print tosend


  • If it is resetting, then somehow you must be triggering the Auto-Reset feature, that we use in programming.  So, you need to disable the RTS# line on the FTDI interface.

    The solution, I believe, is found here: 

    Explicitly disable the RTS as follows:
    myport=serial.Serial('/dev/ttyUSB0',19200, rtscts=1)


    Please let me know if that fixes it!
  • I double checked, and my previous attempts were using the EvilMadScientist USB to TTL cable, which has a six pin connector on the TTL end. I tried the Python with rtscts=1, rtscts=True, rtscts=False. Same result on all, clock just resets.

    I switched to the AdaFruit cable that has only four pins on the TTL side, and each pin is a separate female pin. I did not connect power, just ground, TX, and RX. Works great now...
  • Okay, so there must be something still screwy about the Pi's USB driver.  Good to know for future reference, at least. 
  • I have done a bit of programming in Python on a Raspberry Pi for sending data to an Alpha Clock Five. My clock has firmware version 2 with the GPS extensions, so if you have a different firmware, you might need to make changes. Please let me know if you find it useful, comments, corrections, etc...

    Files in the above compressed archive: - Library module, imported into each of the other files. If you just run it, all variables are displayed.

    brightness - expects a command line parameter of an integer between 1 and 11.

    reset - set all parameters back to somewhat sane defaults and sets the mode back to display time.

    scroll - expects a quoted string of any length, a delay between updates, and a number of times to loop (between 1 and 99)

    bedtime - I plan to add this to crontab to run at 8:15 PM to tell my three year old it is time for bed...
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