3 Hardware, Software, Testing Requirements, and Test Results
3.1 Firmware and Programming
This reference design uses the SCB to control the different ICs on board. The firmware for this design was
developed using Code Composer Studio. Once the SCB is flashed with the proper firmware, it can be used
along with this reference design. Since the SCB can be used with multiple EVMs, it can easily be flashed by
using the GUI to upload the proper firmware.
Board Connects to USB
Initialize MSP432 I2C
pins
Board Receives
Power
Initialize LDC3114
devices with settings for
specific coil design
Initialize TMAG for angle
and magnitude reading
Initialize DRV2605
Run calibration on LRA
Setup I2C triggering for waveform
playback
Initialize LED drivers
Give visual feedback on LEDs that
initialization is done
Figure 3-1. Initialization Flowchart
The firmware for this design starts by initializing the different ICs on the board. The LDC3114s are setup for
the button application and set the registers according to the coil design discussed above. The DRV2605 haptic
driver is setup to perform haptic feedback when and I2C command is received. The device is also setup for the
specific LRA that is attached to the board and runs a calibration check each initialization. The TMAG5273 is
setup so that the X and Y components of the magnetic field are used for rotational calculations. This device can
also be configured to send interrupts under specific conditions, but that is not used in this design. Additionally,
each mode in this design uses the angle from the TMAG5273 to determine which LED to turn on for the dial
position. Since this is acting like a 12-position selector, hysterisis is added to the dial angle output. This prevents
cases where the angle could be right on the line between two LED outputs causing the two LEDs to flicker back
and forth. This has the same impact as included a physical keep out method for the position between each of the
12 LEDs.
Hardware, Software, Testing Requirements, and Test Results
10
Inductive Touch and Magnetic Dial Contactless User Interface Reference
Design
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