A Very Expensive LED Controller
Let’s pick up where we left off in Screenshot 2. We
are going to use the Atmosphere tools to build a simple
application to control the tri-color LED module with an
iPhone, which happens to be a model 5S. As you can see
in Screenshot 2, I have assembled a set of button
elements that are acting as logic triggers for the LEDs we
want to control. I’ve also placed a checkbox in control of
the multi-sensor development kit’s buzzer.
Drawing from the kit’s schematic snippet, I
determined that the gates of the MOSFETs that are driving
the LED module are electrically attached to particular
A20737A GPIO pins. As you can see, the green LED is
controlled via GPIO pin 27. The red LED is under the
thumb of GPIO pin 26, and the blue LED is switched by
the MOSFET gate attached to GPIO pin 28. I assigned a
logical GPIO element to the green LED in Screenshot 3.
; Screenshot 3. The Properties pane allows me to assign a
logical button trigger and GPIO control element to physical
pin 27 of the A20737A AIR module.
; Schematic 1. This
is an excerpt from
schematic you can
download from the
; Screenshot 4. The Atmosphere programmer loads the
application code into the multi-sensor development kit
hardware via the FT2232HL and its USB interface.
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