Name:______________________________ ID:________________________
ECE6483 EXAM 2, Fall 2021 Take Home
Directions: Answer all questions completely and submit via Brightspace. Open book, notes etc. Please
do not collaborate. There will be no credit for correct answers without explanation. There will be no
exceptions for late submissions.
1. In class we often use the built in functions provided by the MBED framework. This allows us to avoid
tedious bit manipulations and register configurations. Often when we use sensors or actuators,
there is an accompanying driver which serves the same purpose as the framework does. Let’s
consider the Azoteq series of gesture/touch controllers (datasheet attached).
This sensor communicates I2C to your host controller. The goal of this question is to make a C file
and associated header file that provides a specific driver for that sensor.
Review the I2C section of the datasheet (I have attached the 5 relevant pages).
a. Build a header file (ASensor.h) that provides the following:
a. A #define for the I2C address, #define SENSOR_ADDRESS xxxx
b. Definitions for the following functions
i. Int GetVersion() //Returns Major Version.Minor Version of the sensor
ii. int GetTotalStrength() //Returns the total strength (See datasheet table 8.1)
iii. int GetEvent() //Returns 0 if there is no event or an enumerated value indicating
the event type defined by the bits in register addresses 0x000D – 0x000E in the
sensor (see datasheet table 8.1)
b. Build a C file (ASensor.c) that implements the header you built in part a.
a. Using any of the MBED I2C functions provided (https://os.mbed.com/docs/mbed-
os/v6.15/apis/i2c.html), write the code for sections i. through iii. above.
c. Write the main.cpp in PlatformIO that performs the following:
a. Initialize the I2C driver.
b. Initialize the Serial driver (to output data to the terminal).
d. In the while loop in your main(), call the GetEvent() function every 0.5 second and outputs the
result of the GetEvent function to the serial terminal.
These are the ONLY requirements. You are free to add features or implement the functions any way
that you see fit. You can make assumptions as long as you clearly state and document them.
2. Lets now assume we want to bypass the polling and use a timer/ticker function provided from
MBED instead to call the GetEvent() function. See https://os.mbed.com/docs/mbed-
os/v6.15/apis/ticker.html.
a. Write the code to setup a 0.5 second ticker and implement the “attach”.
b. Write the required code to identify an event and print out the results from the main.cpp
while loop. (NOT THE TIMER FUNCTION)
https://os.mbed.com/docs/mbed-os/v6.15/apis/i2c.html
https://os.mbed.com/docs/mbed-os/v6.15/apis/i2c.html
https://os.mbed.com/docs/mbed-os/v6.15/apis/ticker.html
https://os.mbed.com/docs/mbed-os/v6.15/apis/ticker.html
3. For the above example, add GetTotalStrength() to your while loop and illuminate the on-board LED
with it’s brightness relative to the return from GetTotalStrength(). Meaning, use MBEDs PWM
implementation to “dim” the LED such that weak touch = DIM, strong touch = BRIGHT.