Description
1. Overview
This assignment deals with connecting your ESP32 V2 board to the Internet over WiFi and
exploring sleep modes and wake up sources in the ESP32. You will also be using the RTC
module and the on-board touch sensor in this lab. The hardware and software implementation
details for this assignment are described in the following sections.
2. Programming Exercise
2.1. Hardware Interfacing
You will use the following hardware components:
• The on-board red LED and on-board Neo Pixel
o The red LED should indicate if the board is awake (ON) or in sleep mode (OFF).
o The Neo Pixel should be controlled by touch-based input (see Table 1).
• One external push button as a GPIO input to use as a wake-up source.
• One external Male-Male jumper wire connected to a Touch-enabled pin. Insert the
wire into the header on the board. This page gives information about the Touch-enabled
pins: http://docs.micropython.org/en/latest/esp32/quickref.html#capacitive-touch. You
can select any of the 10 capacitive-touch enabled pins on the board with the following
caveat. The pins indicated on the webpage above are for the ESP32 microcontroller
itself. On your board however, only 6 out of the 10 touch-enabled pins are available for
use. You can figure out the 6 pins by trial and error (HINT: you will get a ‘ValueError’
if you try to assign an unavailable pin as a TouchPad input).
2.2. Software Implementation (main.py)
Your program should implement the following functionality.
© Vijay Raghunathan and Soumendu K. Ghosh, Purdue University 2 | Page
2.2.1.Connect to the Internet over WiFi
• The program should use the network module in MicroPython to connect your ESP32 to a
WiFi network using the ‘SSID’ and ‘Password’ for that network. You can create a WiFi
hotspot on your mobile/laptop and connect your ESP32 to the hotspot. Refer to the example
given in the MicroPython documentation for the network module Error! Reference
source not found.
e.g., if your mobile hotspot has an SSID: ‘Lenovo-SSID’ and Password: ‘12345678’, then
use this SSID and password for connecting the ESP32 to the Internet.
NOTE: You can also connect to any other WiFi network which works directly with an
SSID and password. However, be aware that enterprise networks such as PAL3.0 which
require SSID, username, password, certificates, etc., are unfortunately not supported in
MicroPython.
• Each time the board successfully connects to Wi-Fi, the program should print the SSID it
has connected to and the interface’s IP address.
Connected to Lenovo-SSID
IP Address: 192.168.0.107
2.2.2. Display Current Date and Time using Network Time Protocol (NTP)
• Get the current time from the Internet using NTP. The program should fetch the current
date and time from the NTP server ‘pool.ntp.org’ and use it to set the RTC (real time
clock). HINT: check module ntptime. Then, manually adjust the RTC to convert UTC
(Coordinated Universal Time) to the current local time zone in West Lafayette.
• Similar to lab 2, initialize a hardware timer and display the current date & time every 15
seconds. Do not use time.sleep(). Instead, use the RTC and Timer interrupt/callback like
you did in Lab 2. Format the date and time as shown in the example below:
Date: 09/29/2021
Time: 10:00:00 HRS
2.2.3. NeoPixel Control by Touch Input
• Initialize the Touchpad-enabled pin connected to the jumper wire and calibrate it by
observing how the touchpad pin values change when you physically touch the jumper wire.
• Initialize a second hardware timer and read the touch pin values every 50 milliseconds
using a Timer interrupt/callback and implement the following pattern. Use calibrated values
to detect whether the wire is touched or not.
o Touch Pin not touched: Neo Pixel should be OFF
o Touch Pin touched: Neo Pixel should be ON and lit GREEN
© Vijay Raghunathan and Soumendu K. Ghosh, Purdue University 3 | Page
2.2.4. Red LED, Deep Sleep, and Different Wake Up Sources
• The red LED should be ON whenever the ESP32 is awake and OFF when it is in sleep
mode.
• Use a third hardware timer to put the ESP32 into deep sleep every 30 seconds for a duration
of 1 minute. Print out a message on the terminal before going to sleep like:
I am going to sleep for 1 minute.
AWAKE duration: 30 seconds (this will be the duration of the third hardware timer)
SLEEP duration: 1 minute (do not need a timer for this, check this link for details on deep
sleep: https://docs.micropython.org/en/latest/esp32/quickref.html#deep-sleep-mode)
• You will be using two different sources of waking up from deep sleep. Your program
should check for both sources and the board should be able to wake up from either source.
2.2.4.1. Wake up Sources
• Timer Wake Up: Wake up the ESP32 after the predefined sleep duration (1 minute)
and print that it’s a timer wake-up.
• External Wake Up Mode 0: Configure the switch as an external wake-up source.
Pressing the switch within the 1-minute sleep duration should wake up the board and
print out it’s an EXT0 wake-up. If one-minute passes and no touch is detected, then
your board should wake up due to the Timer Wake Up above.
2.3. Overall Program Flow and Sample Output
The board is powered on for the first time. It connects to the Wi-Fi network, fetches the current
time from NTP server, displays them after 15s, and turns on the Neo Pixel to green whenever
the touch pin wire is touched. It again displays the date and time at 30s and then goes to deep
sleep. The program now checks for the push button wake-up signal. If you press the switch or
if 1 minute expires, the board wakes up and starts the overall process again. Table 1 shows the
LED status functionality. A sample output is also provided here for your understanding. For
this sample, we assume that the program started at 10:00:00 hrs. EST.
Table 1. Sleep and Wake Up Program Flow
Mode Touch Pin Switch Red Led Neo Pixel
Sleep Not Pressed: No Effect Not Pressed: No Effect Off Off
Sleep Pressed: No Effect Pressed: Wake-Up Off Off
Awake Not Pressed: Neo Pixel off Not Pressed: No Effect On Off
Awake Pressed: Neo Pixel green Pressed: No Effect On Green
Sample Output
I (200) wifi: wifi driver task: 3ffe2c34, prio:23, stack:3584, core=0
………
………
………
Wi-Fi connection
messages posted by
ESP
© Vijay Raghunathan and Soumendu K. Ghosh, Purdue University 4 | Page
I (22233) network: CONNECTED
I (22883) event: sta ip: 192.168.0.107, mask: 255.255.255.0, gw: 192.168.0.1
I (22883) network: GOT_IP
Connected to Lenovo-SSID
IP Address: 192.168.0.107
Date: 09/11/2019
Time: 10:00:15 HRS
Date: 09/11/2019
Time: 10:00:30 HRS
I am going to sleep for 1 minute.
ets Jun 8 2016 00:22:57
rst:0x5 (DEEPSLEEP_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee……………
…………………
…………………
I (0) cpu_start: Starting scheduler on APP CPU.
Woke up due to EXT0 wakeup.
I (200) wifi: wifi driver task: 3ffe2c34, prio:23, stack:3584, core=0
///continues
3. Submission
Make sure you follow these instructions precisely. You need to turn in your code on
Brightspace. Please create a directory named username_lab3, where username is your
CAREER account login ID. This directory should contain only the following files, i.e., no
executables, no temporary files, etc.
1. main.py: your program (2.2)
2. A README file named username_lab3_README.txt that contains a description of
your hardware connections (which pins you used, exactly what they were connected to,
etc.).
Zip the directory and name it as username_lab3.zip and upload the .zip file to Brightspace.
BONUS CREDIT: You will receive 20% bonus credit on the lab for creating a short video
that shows you demonstrating your working solution (explain your hardware connections
briefly before demonstrating the working solution). Please do not upload video files directly
on Brightspace. Instead, upload the video to YouTube (or other such video hosting platform)
and include the link to the video in your README file above.
4. Grading
We will use a combination of automatic grading scripts and manual code inspection for
evaluation. If your code is unusually complex or substantially different from expected
solutions, you may be asked to attend an office hour and explain your code.
Default Messages
by ESP on Wakeup
and Reset
© Vijay Raghunathan and Soumendu K. Ghosh, Purdue University 5 | Page
REFERENCES
[1] Getting started with MicroPython on the ESP32
https://docs.micropython.org/en/latest/esp32/tutorial/intro.html
[2] ESP32 PICO MINI 02 Datasheet
https://www.espressif.com/sites/default/files/documentation/esp32-pico-mini02_datasheet_en.pdf
[3] ESP32 Technical Reference Manual
https://www.espressif.com/sites/default/files/documentation/esp32_technical_reference
_manual_en.pdf
[4] Adafruit HUZZAH32 – ESP32 V2 Feather Online Manual
https://learn.adafruit.com/adafruit-esp32-feather-v2
[5] Adafruit ESP32 Feather Pinouts: https://learn.adafruit.com/adafruit-esp32-featherv2/pinouts
[6] MicroPython GitHub https://github.com/micropython/micropython
[7] REPL http://docs.micropython.org/en/latest/esp8266/tutorial/repl.html
[8] Thonny IDE https://thonny.org
[9] Rshell GitHub https://github.com/dhylands/rshell
[10] Sleep Modes API in C https://docs.espressif.com/projects/esp-idf/en/latest/apireference/system/sleep_modes.html
[11] Touch Sensor API in C https://docs.espressif.com/projects/esp-idf/en/latest/apireference/peripherals/touch_pad.html
[12] ESP32 specific functionalities in MicroPython
http://docs.micropython.org/en/latest/library/esp32.html