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9. INPUT DEVICES

Task for this week Input Devices

Group assignment:

Probe an input device(s)'s analog levels and digital signals Document your work on the group work page and reflect on your individual page what you learned

Individual assignment:

Measure something: add a sensor to a microcontroller board that you have designed and read it.

GROUP ASSIGNMENT

In the Week 9 group assignment, we explored how to probe and analyze signals from input devices using an oscilloscope. We worked with a digital microphone (INMP441 MEMS) and an analog joystick (PS2 Joystick Module), successfully visualizing their respective digital and analog signals. This involved learning oscilloscope calibration, adjusting voltage/time scales, zooming into waveforms, and analyzing real-time signals. Additionally, we understood the differences between digital and analog signals, proper power supply setup, and efficient probing techniques. This hands-on experience enhanced our understanding of signal characteristics and oscilloscope usage.

Group Assignment

Rotary Encoder

I have decided to use Rotary encoder as my input device . I Read some basic datasheet to understand the working of the Rotary encoder .

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I understood how the A, B and C button plays an important role in the clockwise and anticlockwise rotationary movement .

DESIGNING THE PCB

Then i searched in Snepeda to find the Schematic and footprint of the rotary encoder . then i have added it to the kicad library . For that you could refer week 2 documentation .

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ESP WROOM 32

You could go through the below link to understand the basic pinout and its functions .

DOIT ESP32 DevKit V1 Wi-Fi Development Board - Pinout Diagram & Arduino Reference - CIRCUITSTATE Electronics

then i Refered The Data sheet to Get Some Understanding Since We are not using the Module . We are only using the chip

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Before designing as my instructor told . we referred to Neils Circuit design to get an overview . The circuit was a good help in the design process of my circuit board .

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FREE ROUTER ADJUSTMENT

For Routing the pcb , i used the free router plugin that is available on kicad . The below are the settings that i changed on the free router to set the size of traces .

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The below image is my schematic design .

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Schematic Explanation

  1. Rotary Encoder:
    • The rotary encoder (S1: WS-ENTV_4820XX514001) is connected to GPIO pins of the ESP32 for detecting rotation direction and button presses.
    • Pull-up resistors (R1, R2, R3: 10kΩ) ensure proper signal levels for CLK, DT, and SW pins.
  2. ESP32 Microcontroller:
    • The ESP32-WROOM-32 module serves as the central processing unit.
    • Essential pins like EN (enable) and RX/TX are connected for programming and debugging.
  3. Voltage Regulator:
    • A linear voltage regulator steps down 5V to 3.3V to power the ESP32.
    • Capacitors (C1: 10µF, C3: 1µF) are placed on the input and output sides of the regulator for stability.
  4. Decoupling Capacitors:
    • A 0.1µF capacitor (C2) is placed near the ESP32 power pins to filter high-frequency noise.
  5. Boot and Enable Switches:
    • Tactile switches (SW1, SW3: Omron B3SN) are used for boot mode selection and resetting the microcontroller.
    • Pull-up resistors (R4, R5: 10kΩ) ensure stable operation.
  6. Programmable LED:
    • An LED (D1: LED_1206) is connected to a GPIO pin via a current-limiting resistor (R6: 100Ω).
  7. RX/TX Header:
    • A pin header (J5: FTDI-compatible) provides external communication for programming/debugging.
  8. Pin Headers:
    • Additional pin headers (J1, J2) are included for modularity and future expansion.

Design Considerations

  • Pull-Up Resistors: Ensure stable HIGH logic levels for input pins.
  • Decoupling Capacitors: Filter out noise and stabilize voltage during high-current events.
  • Voltage Regulation: Protects the ESP32 by providing a steady 3.3V supply.

Then i have arranged the the pcb board by keeping the components on different sides . so i could route it good .

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Then i used the free router as mentioned . I used the extension below .

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I Refered Some Videos and Circuits

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This is what i got after Free routing .

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On DRC checking . i got 78 errors . i have to rectify those errors .

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Many of the Errors was because of Padding Issues . So that i needed to adjust the Pads width .And it solved those

For that Right Click On the Pads > Properties

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Change The Pad Properties as shown below .

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Rather than manually applying the pad properties to all pads, you can automate the task by following these steps:

Right-click on the pad > Push Pad Properties to other pads > Change Pads on current footprint .

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Adjusting VIA holes Padding to Fix the error

There was some issues with the via holes too . I was not aware about the what an annular Ring is . so I referred Google And the below Image would help you understand what an annular ring is .

annular ring.jpg

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Then i have downloaded the gerber file and used in the Gerber2Png Website to get the the PNG files .

Turn On the Double side Button If its Double side .

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HOW TO MILL A DOUBLE SIDE PCB

TO MILL A DOUBLE SIDE PCB . YOU SHOULD DOWNLOAD THE TWO LAYER PNG FILE USING THE GERBER2PNG SITE

Then follow the order of the generated file . ie from 0 - 4 . As in my case 5 file was generated .

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Mill the Pcb in the order format of the numbers .

Then i Traced the Front layer and then i have cut the Front Plane Out .

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Then i placed gum on the side that i have milled as shown below . The edges are getting cut in a different shape in the two layer PCB .

IMG-20250325-WA0051.jpg

Then i have kept the PCB back to Milling machine so that i am ready to mill the second layer .

IMPT Note : remember to place the side correctly or you may end up getting milled on the wrong direction .

IMG-20250325-WA0047.jpg

This is the Pcb that i got milled . The Depth was high so the copper on the outside layer is getting removed . and i was not able to use the via .

WhatsApp Image 2025-03-25 at 11.08.08_654386f5.jpg

This is the BOM .

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Then i have requested the components from the fab inventory .

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This is the PCB what i Made .

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The Next Part is the testing the PCB for That i first installed the esp32 library to the arduino ide .

For That i asked the Perplexity and this was the result and i followed it and i was able to install it .

To add the ESP32 library to your Arduino IDE, follow these steps:

Step-by-Step Installation

  1. Install Arduino IDE:
    • Ensure you have the latest version of Arduino IDE installed on your computer. You can download it from the official Arduino website.
  2. Open Preferences:
    • Launch Arduino IDE and go to File > Preferences.

  3. Add ESP32 Board URL:

    • In the Additional Board Manager URLs field, enter the following URL:

      texthttps://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json

    • If you already have other URLs (e.g., for ESP8266), separate them with a comma.

    • Open Boards Manager:
    • Navigate to Tools > Board > Boards Manager.
    • Install ESP32 by Espressif Systems:
    • In the Boards Manager search bar, type ESP32.
    • Locate the entry labeled "ESP32 by Espressif Systems" and click the Install button.
    • Select Your ESP32 Board:
    • After installation is complete, go to Tools > Board, and select your specific ESP32 model (e.g., DOIT ESP32 DEVKIT V1).
    • Test the Installation:
    • Connect your ESP32 board to your computer via USB.
    • Select the appropriate COM port under Tools > Port.
    • Load an example sketch (e.g., File > Examples > WiFi (ESP32) > WiFiScan) and upload it to your board.
    • Open the Serial Monitor at 115200 baud rate to verify functionality.

Prompt Used In Perplexity : how to add esp32 library in my arduino ide

Testing My PCB

Then i tested the the Pcb By running a sample code to Blink the Led . It was working

Next i was ready to test my rotary encoder . and for that i referred sayanth s a previous fab alumini and i tried to replicate the code so that i can check the working .

But the code was not working . i tried using various codes across internet . but nothing was working . then i asked my instructor saheen and he helped me finding the missing connection . (or like a misplacement connection ) .

That time i knew that every thing that i have made so far has gone i realised that whether i should make a new microcontroller . and i was literally confused with like what to do .

Then saheen helped me with the external wiring so we could test the encoder and solve the issue as of now .

Below one is the mistake circuit .

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rotary encoder.jpg

CHANGED THE CIRCUIT TO THIS . (the mistake was i misplaced the switch ).

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The below one is the PCB which is wired . ie the rotary encoder is connected externally in some connections .

after correcting i uploaded the same code and again it was not still working . so i moved to next task .

Setting Date and time in esp32

As my final Project is a Productivity timer . i wanted to incorporate date and time to my module . for that i asked my instructer how to do it . he told me to try with the Ntp server . So i could incorporate date and time .

I searched perplexity how to incorporate the thing .

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Now i used ntp server to get date and time .

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On first the time was not working . so i adjusted the gmt offset values to 19800 which equal gmt +5:30 🕠 .

i was able to generate the output correctly . the output is shown below .

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This is the code that i used . 

#include <WiFi.h>
#include "time.h"

const char* ssid       = "Your wifiname ";
const char* password   = "password";

const char* ntpServer = "pool.ntp.org";
const long  gmtOffset_sec = 19800;
const int   daylightOffset_sec = 0;

void printLocalTime()
{
  struct tm timeinfo;
  if(!getLocalTime(&timeinfo)){
    Serial.println("Failed to obtain time");
    return;
  }
  Serial.println(&timeinfo, "%A, %B %d %Y %H:%M:%S");
}

void setup()
{
  Serial.begin(115200);

  //connect to WiFi
  Serial.printf("Connecting to %s ", ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
      delay(500);
      Serial.print(".");
  }
  Serial.println(" CONNECTED");

  //init and get the time
  configTime(gmtOffset_sec, daylightOffset_sec, ntpServer);
  printLocalTime();

  //disconnect WiFi as it's no longer needed
  WiFi.disconnect(true);
  WiFi.mode(WIFI_OFF);
}

void loop()
{
  delay(1000);
  printLocalTime();
}

Code parameters Explanation

    • gmtOffset_sec: 19,800 seconds = 5.5 hours (IST offset)[^4][^8]
    • daylightOffset_sec: 0 for India (no daylight savings)
    • ntpServer: Global NTP pool for reliability[^4] ``-getLocalTime()` fetches current time from ESP32's RTC
  • Format specifiers:
    • %A: Full weekday name (e.g., "Wednesday")
    • %B: Full month name (e.g., "March")
    • %d/%Y: Day/Year in numbers
    • %H:%M:%S: 24-hour time format

CONCLUSION

For Week 9, I worked on designing and implementing input devices, focusing on a rotary encoder integrated with an ESP32 microcontroller. I created a detailed schematic in KiCad, ensuring proper connections for the rotary encoder, boot and enable switches, programmable LED, and RX/TX communication. The design included decoupling capacitors and a voltage regulator for stable operation. After resolving issues like pad sizing and routing errors, I generated Gerber files and milled a double-sided PCB. I programmed the ESP32 in Arduino IDE to test the rotary encoder functionality, troubleshooting initial wiring errors but it didnot worked out . Additionally, I incorporated NTP server functionality to display real-time data, aligning with my final project goals.

Files

Milling Files

Kicad files

Last update: April 7, 2025