PHYS 523 :: Physics Illinois :: University of Illinois at Urbana-Champaign

Instrumentation and Applied Physics Project

Code and design resource repository

There is a lot of material here, some of which may be useful! Be patient and dig though it.

arduino_demo.ino

Arduino demo code, referred to in a microtutorial.

simple_python_example.py.txt

Simple python program to draw some circles. (Strip off the ".txt" from the filename to run.)

Code to test "Big Board"

See the Circuit schematics page for the GCM4_RadioFeather_data_logger5.pdf PCB design. This is the July 2023 board with both Grand Central M4 and RadioFeather M0 processors. This long program tests most everything on it.

Software archaeology: code to test some of the Fall 2021 hardware

Arduino code to take 2048 x 1536 jpegs with a Sony Spresense camera, and write them to a microSD memory.

Code to test some of the (Physics 398DLP) Spring 2021 hardware

Dealing with Arduino libraries

1, Go to the Adafruit site and look for the entry page into the company's BME680 material.
2. Find (and follow) the link to the "detailed tutorial" about the BME680.
3. Find (and follow) the link to the "Arduino Wiring & Test" page. (We'll be using the I2C version of wiring the BME680.
4. On that page find the section titled "Install Adafruit_BME680 library" and follow the directions. The directions are very clear, and even have screen shots.

A lengthy C++ and Python refresher: material from an earlier course

Super-duper data logger from a few years ago, and GG's sample Arduino code for various devices

Read an electret microphone through an Adalogger ADC pin A1 and write its data to SD files, with each file holding 10,000 samples. 12-bit data are recorded at about 16 kHz; there's about a 120 millisecond gap between successive files due to the amount of time to write to SD. The program writes 20 files each time it is run.
Here's a python program that will read the electret microphone (binary) audio file, take its Fourier transform, and make a couple of plots. (Strip off the .txt file extension to run.)
Simple GPS code based on an Adafruit example. Start with this... Also see the GPS microtutorial, which will be available soon.
Code to explore the behavior of the Arduino Mega 2560's millis() and micros() functions by using GPS PPS (pulse per second) signals. The code uses two different methods to interrogate the Arduino pin receiving the PPS signal: digitalRead(), which takes about 3.84 microseconds per call, and a direct reference to the appropriate I/O port via a (*myPin_port & myPin_mask) statement. The latter is much faster, executing in about 630 nanoseconds. I find that the clocks on two different (Italian) Arduinos differ by about 0.06%, which corresponds to a processor-to-processor discrepancy of about 600 microseconds per second. You'll need your GPS module to have found satellites before you run my code. The code doesn't try to talk to the GPS, and only looks at Arduino pin D43 for a PPS signal without caring about anything else that might be going on with the GPS. There are lots of comments, so this is easy to use and adapt.
Test an Arduino that reads one or two INA219s, one with (default) I2C address of 0x40 and the other (if installed) with address 0x41.
Here is the code I used to check the PCBs before distributing them to the fall 2020 class. The code looks at the INA219(s), BME680, microSD breakout, GPS, keypad, LCD, RTC, and microphone RMS in one-second intervals..
An early-inb-the-semester demo: reading a BME680 with an Arduino
Set a DS3231 real time clock to local time
GG's data logger schematic for the spring 2021 version
Very simple circuit with an Arduino, a BME680, and an LCD. (spring 2021, in class, week 1)
The schematic for the fall 2020 group 3 PCB is a little different. Here it is.
Code from the spring 2019 dust group (with some mods by GG) to read data from a PMS5003 airborne particulates sensor.
GG's code to handle radio communications between a pair of Adafruit Feather M0s equipped with RFM95 LoRa (Long Range) radios. You'll need a pair of Radio Feathers with whip antennas of the right length. (These are 1/4 wavelength, which is 3 inches for 915 MHz.) The program asks whether a microcontroller is meant to initiate communications or to respond when it "hears" something.
GG's proto-DAQ for an Adalogger Feather M0, of the sort used by the Drone Warriors. The code talks to a GPS module, a BME680, and an MLX90614 IR non-contact thermometer. The GPS data is written to a microSD card.
Circuit schematic and PCB layout for the Adalogger Feather M0 version of the p398DLP data logger.
GG's data logger schematic and PCB layout for fall 2019
GG's data logger schematic, February 8, 2019 version
PCB layout for February 8, 2019 version
GG's data logger schematic, fall 2018 version
Read GPS and BME680 data, and write them to the microSD memory
Unit 1 blinking LED code
Repeated microphone RMS measurements, half-second intervals
16 x 2 LCD code
4 x 3 keypad code
MCP4725 DAC code
ADXL326 accelerometer calibration code
microSD card read/write (plain text) code
32 kHz audio recording to binary file code, now corrected for output buffer overwrite-related problem (needs keypad and LCD
32 kHz audio recording to binary file AND read/report the temperature read from a BME680 (Arduino code that needs keypad and LCD)
32 kHz audio recording to binary file AND read/report BME680 readings, with VOC gas measurement disabled. (Runs faster this way!)
Read temperature, pressure, and humidity from a BME680, but disable the volatile organic compounds gas measurement. This runs considerably faster than a version in which the gas measurements are performed.
Python code to read an Arduino binary audio file and (optionally) write a WAV format version. I include a short snippet of the Rolling Stones recorded by my Arduino for you to practice with. Note: if your laptop complains of memory errors, try reducing the value of max_buffers from its current (very large!) value of 50,000,000.
Arduino code to read from the GPS breakout board and set the real time clock from the GPS clock. You may want to change the program's insistence on having you enter year, month, day information from the serial monitor.
Much better Arduino code to set the real time clock from the GPS clock. Use this program instead of the older version, above. I think it'll synchronize your DS3231 RTC so that it is within about two milliseconds of the GPS system's clock. You will need to have connected the GPS board's PPS pin to the Arduino's D43. (That requires a wire that's about a half-inch long to be soldered onto your PCB. It's a very simple patch.) The program will wait until your GPS device sees satellites, though, so do this outdoors, or someplace where there's a decent GPS signal.
GG's Arduino code to read various sensors, taking keypad input from the user. Available functions are these:

noop (no operation) = ✳NOO# = ✳666#
display Real Time Clock value = ✳RTC# = ✳782#
display ax, ay, az = ✳ACC# = ✳222#
display battery voltage and current = ✳BAT# = ✳228#
measure audio power, 1 second duration = ✳AUD# = ✳283#
display GPS information = ✳GPS# = ✳477#
display temperature = ✳T# = ✳8#
display pressure = ✳P# = ✳7#
display (relative) humidity = ✳H# = ✳4#
display VOC reading = ✳VOC# = ✳862#
display infrared sensor temperature = ✳IR# = ✳47#
calibrate ax, ay, az = ✳CAL# = ✳225#
play audio tones based on keypad selection = ✳MUS# = ✳687#
send help information to LCD = ✳000# = ✳000#
altitude above sea level = ✳A# = ✳2#
laser range finder distance (mm) = ✳D# = *3#
repeat last command = ✳# = *#

Atmel microcontroller and Arduino Mega 2560

EAGLE schematic capture and PCB tools

An EAGLE parts library: put into an external_lbrs folder, then have EAGLE open the parts you need. Latest updates: January 25, 2024. Lots of small changes and new devices; better pushbuttons.
How to Install and Setup EAGLE: A tutorial on the SparkFun web site.
Using EAGLE: Schematic.: Another tutorial from SparkFun.
Using EAGLE: Board Layout: a tutorial on laying out a PCB once your circuit is defined. Also on the SparkFun web site.
"Every Layer in Autodesk EAGLE and What You Need to Know About Them"
EAGLE circuit design files for fall 2021 group 1
EAGLE circuit design files for fall 2021 group 2
EAGLE circuit design files for fall 2021 group 3
EAGLE circuit design files for fall 2021 group 4

3D printing; construction tips and techniques

UM2plus_set_nozzle.curaprofile: Cura 3.5.1 settings profile. Download and use this for a Cura slicing with a UM2+ target machine.
Cura 3.5.1 settings I use for an Ultimaker 2+ 3D printer (a PDF file of screen shots). I find that poor adhesion of the PLA (poly lactic acid) plastic to the printer's glass build plate is the principal difficulty to be overcome. Here's what works for me: (1) Keep the glass build plate scrupulously clean, and wipe it down with 70% isopropyl alcohol (ordinary rubbing alcohol, which is a 70-30 mix of alcohol and water) before each print job. The water content is important, since there'll probably be a 100 nm thick layer of water that adsorbs to the glass surface when you wipe it down. Pure isopropanol will strip this away, and you won't have all those helpful hydrogen bonds from the water to hold the plastic to the glass. (2) Don't apply glue, masking tape, or any of the other suggested toppings you might read about (chocolate sprinkles?) to the glass. (3) Do a quick adhesion test, using this STL file, which you'll need to turn into gcode. It runs in a little less than 9 minutes on an Ultimaker 2+ with a 0.6 mm nozzle if you load the Cura 3.5.1 profile UM2plus_test_no_brim.curaprofile first. (4) Adjust the nozzle and build plate temperature. I find that dark colors of PLA require higher temperatures than light colors. Black, for example, works nicely with a 235°C nozzle and 65°C build plate.
Cura 3.5.1 profile for Ultimaker 2 (not 2+)
Cura 3.5.1 profile for adhesion tests with Ultimaker 2 (not 2+)
Cura 3.5.1 profile for Ultimaker 2+
Cura 3.5.1 profile for adhesion tests with Ultimaker 2+
Breadboarding guide

Sensors and other hardware

Adafruit Industries website
CrystalFontz LCD
Adafruit tutorial for their microSD breakout board
DS3231 real time clock
Bosch BME680 temperature, pressure, humidity, volatile organic compounds sensor
GPS module data sheet
GPS NMEA command description
More GPS information
Texas Instruments HDC1000 humidity and temperature sensor
Melexis MLX 90614 IR thermometer
Maxim microphone preamplifiers (rotating the underside potentiometer COUNTERCLOCKWISE increases the amplifier gain)
Microchip MCP4725 12-bit digital-to-analog converter

A table that includes I2C addresses for some of your hardware... and a link to Adafruit's list of I2C addresses for their devices.

part	description	I2C address
0.1uF capacitors	for 5V bypass
10kohm	sets contrast for LCD
16 × 2 LCD	liquid crystal display
22 gauge wire	for breadboarding, various colors
3 x 4 keypad	tap tap tap
AA batteries and case	power to go
Adapter Cable	for GPS antenna
Arduino Mega 2560	microcontroller
Black cardboard box	for your breadboard
BME680	T/P/RH/VOC	0x76 or 0x77
Breadboard	for building your prototype; on loan
CR1220 batteries	batteries for GPS and RTC
digital multimeter	on loan for the semester
DRV2605L	haptic vibrator driver	0x5A
DS3231	real time clock	0x68
electret microphone	amplified microphone	analog output
EMG electrodes	Electromyogram electrodes
eye protection	on loan for the semester
Force-sensitive resistors	Just like it says
GPS Antenna	External Active Antenna
GUVA	Analog UV sensor	analog output
Haptic feedback	motorized vibrator
INA219	voltage/current sensor	0x40
L3GD20H	Triple-Axis Gyro Breakout	0x6B
LSM9DS1	accelerometer/magnetometer/gyroscope	0x1E
MCP4725	DAC, 12-bit, I2C	0x62
MicroSD card breakout	holds microSD card	SPI
MicroSD memory card	8 GB SDHC
Mini Metal Speaker	8 ohm 0.5W
MLX90614	IR thermometer	0x5A
MMA8451	±2 g accelerometer	0x1D
MyoWare	EMG muscle sensor	analog output
of/off/on/off pushbutton	battery vs. USB power
P164 GP2Y0A21YK0F	IR distance sensor	analog output
PAM8302	PWM audio amplifier	PWM analog output
Pink plastic bag	your toy bag!
PM2.5 PMS5003	airborne particulate monitor	UART RX/TX
QS-FS01	anemometers	analog output
T-slot photointerrupter	counts blades	phototransistor output
TCA9548A mux	I2C multiplexer	0x70
Tiny camera	Adafruit “mini spy camera” part 3202	MicroSD; USB
TSL2561	Digital Luminosity/Lux/Light sensor	jumper to 0x39
tweezers	on loan for the semester
ultimate GPS	cool navigation device	UART RX/TX
USB cable	talk to the Arduino
VL53L0X	Time of Flight Distance Sensor	0x29
wire stripper	on loan for the semester