ElMo - menus and configuration files

We have continued to tweak ElMo this week - our hardware is as ready as it will ever be, so it is all about the testing and subsequent software changes.  We have now added a configuration file so we can get and set key parameters from the OLED menu.  The parameters we can tweak as of now are

• voltage in - because when the batteries get used up, the motors slow down and we want to compensate for that.  
• voltage out - so we can recklessly run our 6V motors at 9V during the speed test ;)
• time1m - this records how long to run the motors to travel 1 metre (used during 3 point turn)
• time360 - records how long to run the motors to rotate 360 degrees (ditto)
• slowprox - the speed to run the motors at during the slow approach phase of the proximity test (the default 0.25 was not enough to move ElMo forward when the batteries were running low, so we can increase that now)
• linefollowspeed - the speed to run the motors at during the line following challenge.  We have a better chance of staying on the line when we move slowly, but we can increase the motor speed to go for a faster lap.  Our line following is a bit hit and miss - I'm hoping that is due to the low quality construction values on our test course and that the sensors will perform well on the day.

I'd refer the interested user to our bitbucket source code to see the configuration file (elmo.cfg) and how it is used  (search in elmo.py for eg "voltagein").  We use the python ConfigParser module to read the config file (elmo.cfg) as part of the ElMo __init__ method.  We can get a numeric value from the config file using the getfloat method.  Parameters are set by calling eg setvoltagein (each of the setter methods is listed in our OLED menu list) - this in turn calls the method changevalue, which displays a value on the OLED screen and uses the up down buttons to change the value by an increment (0.01 for slowprox, 0.1 for settime1m, 1.0 for voltage out) and the centre button to return the new value.  When we have changed a value we call the writeconfig method to write the updated config file to disk.  This means that next time we reboot ElMo, we read the most recent configuration.

Here is some video demonstrating the menu in action - with a bit of last weeks Nigella in the background.  Do we get bonus points for having to work under these conditions ;) The font we are using is called Mario-Kart-DS which we found on dafont.com - seemed a bit more appropriate than Times New Roman ;)

This week we shall be testing, testing and retesting - and recording more video to share in the final week running up to PiWars - eek!