Alpha Clock Five and serial in Python from a Raspberry Pi

rolf

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...

#!/usr/bin/python
#
# Rolf Mikkelson. 27-FEB-2013
#
import serial
header = chr(0xFF)
# print "header = ", header
myport=serial.Serial('/dev/ttyUSB0',19200)
tosend="B00111234567"
# print tosend
myport.write(header)
myport.write(tosend)
myport.close()

Windell Oskay

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: 

http://iijean.blogspot.nl/2012/05/ftdi-usb-driver-woes-on-debian-livecd.html ;

(via raspberry pi forum: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=32&t=6832 )

Explicitly disable the RTS as follows:

myport=serial.Serial('/dev/ttyUSB0',19200, rtscts=1)

 

Please let me know if that fixes it!

rolf

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 https://www.adafruit.com/products/954 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...

Windell Oskay

Okay, so there must be something still screwy about the Pi's USB driver.  Good to know for future reference, at least. 

rolf

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...

rolf@mikkelson.info

https://mikkelson.info/AlphaClockFiveSerialRaspberry/AlphaClockFiveSerial.tgz

Files in the above compressed archive:

AlphaClockFiveSerial.py - 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...