IR Homing Module Integration, Part VI

Posted 13 September 2017

While I was doing the work that led to the last post, I realized that my el-cheapo stepper motor was just barely able to get out of its own way.  This worked OK for the previous setup,  but when I moved to a larger sunshade arrangement, I started having problems with the torque – or lack thereof.  As I normally do when faced with this sort of obstacle, I hopped onto the Adafruit site and ordered a couple of NEMA17 stepper motors and companion driver modules.  When these arrived a few days ago, I started playing around with them in preparation for testing the upgraded sunshade.

NEMA17 200 steps/rev stepper motor from Adafruit

This stepper model is the one used widely in 3D printers, and they have excellent speed and torque specs.  The only downside is they run very hot – hot enough to burn fingers :-(.

After receiving the units from Adafruit, I spent some quality time on the web figuring out how to drive them. I discovered that I could use the same L289 motor drivers that I am using for my robot motor driver, so that was cool.  Here’s a short video showing it running an example sketch using the L289 driver


Next I printed up an adapter so I could mount my new, improved sunshade (with OSRAM SFH-314 phototransistors installed), and soon had the whole thing running, as shown in the short video below

Then I ran my IRBeaconHomingModule program in conjunction with my TeensySweepGen and Teensy_NEMA17_L289_RotaryTable programs to perform an azimuth scan of the new sunshade with OSRAM SFH-314 photo transistors installed in a crossover configuration, as shown in the following short video


Next, I modified my little IRBeaconStepperMotorTracker sketch for compatibility with the L289 motor driver, and used it to demonstrate IR beacon tracking with the new sunshade design and the OSRAM SFH-314 phototransistors, as shown in the following short video


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