Recruting SW Microcontroller Eagle Application project

This is the project with witch I'm applying to enter the Eagle Team (UniTn). The task consisted in creating a firmware for a nucleo board that would read the HALL sensor analog and digital pins and send them thru serial, to plot them on the host pc.

How it works

Finite State Machine

The program flow is primarily controlled by a Finite State Machine with the following states:

• Init: Startup some structs used by the FSM
• Wait Request: Receive commands from the serial to change the output of the Listening state until the on-board button is pressed
• Listening: The on-board led is on , the cli is off and the nucleo is reading analog and digital data from the HALL sensor, the analog data before being sent is processed thru 3 different filters chosen thru the cli, if the on-board button is pressed the FSM transition to Pause
• Pause: Same as Wait Request but the on-board led is blinking with a period of 2000ms and a duty cycle of 50%
• Warning: The state is entered when the digital pin, in the Listening state, reads 0 for more than 5 seconds uninterrupted (not implemented), then it spam WARNING in the serial
• Error: If any error occur in any state the FSM will transition to this state. The on-board led will blink with a period of 400ms and a duty cycle of 50% and in the serial it will be spammed ERROR, the only way to exit the state is by pressing the reset button on the nucleo board

CLI

The command line interface is active only in the Wait Request and Pause states, all the commands modifies the filter applied to the analog data read by the sensor. The possible commands are the following:

• raw: no filter applied
• avg: does the moving average of the last 150 elements
• noise: adds random noise to the signal

How it plots

To plot the incoming data from serial I've decided to use SerialPlot, a simple qt application. First off all connect the board serial to the host pc, then start SerialPlot and import the settings from the serialplot.ini file. Open the connection with the Nucleo Board and press the on-board button to start the reading.

The hardware

• STM32 Nucleo Board C031C6

• HALL sensor

Wiring

Nuclo Board Pin	HALL Sensor
PA4	D0
PB1	A0
+3v3	VCC
GND	GND