10. Output Devices

This week was for output devices where i got to explore for the devices which are required for my final project It will help me as i gear up for my final project.The devices need to be understand fully before trying with the program.Giving the wrong connections and improper power supplies will damage the circuit components mainly the microcontroller.Devices like mini speakers need amplifier like DF Player mini and Mini water pumps requires 3V relay modules to regulate the current flow.

Assignments for week 10:

1. Group Assignment

• measure the power consumption of an output device

2. Individual Assignment

• add an output device to a microcontroller board you’ve designed, and program it to do something

1. Group Assignment.

Group Assignment link is here.

Learnings outcomes from the group assignment:

We worked with different output devices and it helped me understand the need of maintaining or setting the required power like current and voltage for the device.It is important to understand the datasheet of each devices as well as the power source equipment so that there is no potentiial damage to the MCU or to the circuit.

Keep in mind the proper connections and supply the power, current and voltage that the device can support or handle.Always test the function of the devices by using multimeters and DC power supply equipment before actual operation.

Individual Assignment

This week i tried working with a mini water pump with 3V relay module and mini speaker with DF Player mini module.

1. Mini Water Pump with my fabricated Microcontroller baord and Programming.

I will be using this mini water pump with my microcontroller board as an output device.I have choosed to test it as i will be using it for my final project to dispense the soap solution to the user.For now i have XIAO SAMD21 as microcontroller for board.

Specifications of the Mini Water Pump

- Model - JT80SL
- Length(including the inlet) - 53mm
- Diameter - 24mm
- Approximate weight - 30g
- Height(including water inlet) - 31mm
- Water inlet-  Outer diameter 7.60mm and inner diameter 5.75mm
- Water outlet  -Outside diameter 7.30mm and inner diameter 5.30mm
- Voltage range  - DC 2.5V to 6V
- Operating current  - 130mA to 220mA
- Hydraulic head  - 40 to 110 cm
- Flow  - 80 to 120 Ltr/Hour
- Power - 0.4 to 1.5 W.

For more details on this mini water pump, please refer here.

I will be using my fabricated board made during Electronics Design and Electronics Production weeks as shown below.

3V Relay Module v2.0 (HF3FD DFROBOT) for Mini water pump.

This relay module is compatible with 5V Arduino Boards as well as Raspberry Pi and other 3.3V devices. It is specially designed for low voltage devices which works well under 3.3V power supplies.It consists of a wide range of power inputs which also supports 1.8V devies and can handle upto 10 A current.

It has terminals like Normally Open(NO) and Normally closed (NC).This relay module uses a gravity-3pin interface for convenient plugs and no need for soldering.

Specifications for 3V relay module

• Operating Voltage: 2.8V ~ 5.5V
• Input Signal: High Level (≥2.8V); Low Level (≤0.5V)
• Max Switching Current: 10A
• Max Switching Voltage: 35VAC; 30VDC
• Rating Load: 10A@35VAC; 10A@28VDC
• Max Switching Power: 300W
• Operate Time: ≤10ms
• Release Time: ≤5ms
• Dimension: 383320 mm /1.51.30.81 inches
• Mechanical Life: 1 million times
• Electrical Life: 50 thousand times
• Weight: 20 g

Pinouts of the 3V Relay module

For more details please go to my reference link about 3V relay module

Why i need to use 3V Relay Module for my mini water pump?

The JT80SL mini water pump operates at DC 2.5V to 6V. If i control this pump using XIAO SAMD21 microcontroller, the pump requires more current compared to the actual current supply from my microcontroller. Therefore i need this 3V relay module to regulate the current flow.It helps for voltage compatibilty as it ensures proper switching with 3V for pump safely.Hence this relay helps to protect my microcontroller as it isolates the low power control circuit from high current motor circuit preventing potential damage.

I wanted to try the working of the pump by using my microcontroller and DC power source equipment.Here is the idea i received from the chatGPT.

I got the connection ideas from here as follows:

1. Connection of Relay with Xiao SAMD21 MCU

- Relay module pin VCC - 3.3V XIAO SAMD21 MCU
- Relay module pin GND - GND of XIAO SAMD21 MCU
- Relay module pin In  - D2 of XIAO SAMD21 MCU

1. External Power source(DC POWER SOURCE EQUIPMENT)

- 5V to 5V of Xiao SAMD21 
- GND to GND of XIAO SAMD21 

1. Pump wire.

- Pump positive terminal to Normally Open(NO) of relay.
- Pump negative terminal to External GND.

1. Relay pins

- COM pin with external 3V power source.
- NO pin with VCC or positive terminal of water pump.

My rough connection plan with above ideas.

Connections I did the connections by referring above and have used SPD3303X-E Programmable DC Power Supply to test my code and working of my mini water pump with a 3V relay module.

Before i clicked ON the machine, i made sure that all the connections were correct and i had set the voltage to 5V and 0.5A y choosing the channel 2.

Next i had to ready to run the program using the Arduino IDE.I had used the code from the chatGPT.

I selected new sketch under file and pasted the code, followed by select my board and port for the program.

Then did compiling and upload and then clicked on serial monitor.

Codes i used

#define RELAY_PIN 2  // Define relay control pin

void setup() {
    pinMode(RELAY_PIN, OUTPUT);  // Set relay pin as output
    Serial.begin(115200);
}

void loop() {
    Serial.println("Pump ON");
    digitalWrite(RELAY_PIN, HIGH);  // Activate relay (Pump ON)
    delay(5000);                    // Pump runs for 5 seconds

    Serial.println("Pump OFF");
    digitalWrite(RELAY_PIN, LOW);   // Deactivate relay (Pump OFF)
    delay(5000);                    // Wait 5 seconds
}

Codes explanation

#define RELAY_PIN 2 // Define relay control pin

It desfines the Relay pin as D2 of XIAO SAMD21 which is connected to turn the relay ON/OFF.

void setup() {
    pinMode(RELAY_PIN, OUTPUT);  // Set relay pin as output
    Serial.begin(115200);
}

The above function explains that D2 is configure as output which can control the relay and serial communication startes from 115200 baud rate.

void loop() {
    Serial.println("Pump ON");
    digitalWrite(RELAY_PIN, HIGH);  // Activate relay (Pump ON)
    delay(5000);                    // Pump runs for 5 seconds

The above function means that prints Pump ON to serial monitor making relay input pin to activate high with 3.3V and pumps activates ON for 5 seconds.

Serial.println("Pump OFF");
    digitalWrite(RELAY_PIN, LOW);   // Deactivate relay (Pump OFF)
    delay(5000);                    // Wait 5 seconds
}

The above codes explains to print Pump OFF to serial monitor making relay input pin to low and waits for 5 seconds before it starts another loop.

2.Running a program to test Mini speaker with my Microcontroller board.

Our lab has that mini speaker.I am choosed to test this as output device because i wanted to use a speaker for my final project.

Specifications for the speaker

- Model DXP21W-A
- Impedance 8 ohm
- Nominal Power 0.25 w
- Maximum Power 0.5 w
- Resonance Frequencyi Foi 700 Hz
- Response: 200~5KHz
- S.P.L: 87 dB
- Height 7.0 mm

To learn more details, here is my link for Mini speaker.

However an amplifier is necessary for this speaker.I will be using the DF Player as it has built-in amplifier.

About DF player for mini speaker.

It is a small, compact audio player and amplifier designed for use with speakers. It helps to decode MP3 and WAV files from microSD card that has an onboard amplifier, driving the small speakers.It can be used in combination with Arduino UNO board or other boards that have RX/TX capabilities.

Specifications for DFRobot DF Player

- Supported sampling rates (kHz): 8/11.025/12/16/22.05/24/32/44.1/48
- 24 -bit DAC output, support for dynamic range 90dB, SNR support 85dB
- Fully supports FAT16, FAT32 file system, maximum support 32G of the TF card, support 32G of U disk, 64M bytes NOR FLASH
- A variety of control modes, I/O control mode, serial mode, AD button control mode
- Advertising sound waiting function, the music can be suspended. when advertising is over in the music continue to play
- Audio data sorted by folder supports up to 100 folders, every folder can hold up to 255 songs
- 30 level adjustable volume, 6 -level EQ adjustable

Here is the link for dfplayer that i have referred.

Pin Description of DF Player mini

source link from here

I have collected the required materials for the connections.

I have fixed the DF player 1K ohm resistor on the bread board and connected the RX to D4 of my MCU board via the 1K ohm resistor. TX was connected to D3 of the MCU board.While SPK1 and SPK2 of DF Player are connected to the terminals of mini speaker.Moreover, i have connected VCC of DF Player to VCC(5V) of my MCU and its GND to GND of MCU board.

Then i had made a folder named MP3 and added mp3 audio files which were named as 0001 & 0002 inside the micro SD card.I had inserted the SD card into the slot of DF Player.

The codes i used was referred from my friend Tshering Dorji.I have changed the volume to 25 and delated the code for third audio play.

So here is the code i used for running the program in Arduino IDE.

#include <DFRobotDFPlayerMini.h>
#include <SoftwareSerial.h>

// Initialize software serial on pins D3 (RX) and D4 (TX)
SoftwareSerial mySerial(D3, D4); 

// Create DFPlayer object
DFRobotDFPlayerMini myDFPlayer;

void setup() {
  Serial.begin(115200);  // Start hardware serial for debugging
  mySerial.begin(9600);  // Start software serial for DFPlayer

  Serial.println(F("Initializing DFPlayer..."));

  // Initialize DFPlayer
  if (!myDFPlayer.begin(mySerial)) {
    Serial.println(F("DFPlayer initialization failed!"));
    Serial.println(F("1. Check RX/TX connections (must be crossed)"));
    Serial.println(F("2. Insert SD card with MP3 files"));
    while(true);  // Halt if initialization fails
  }

  Serial.println(F("DFPlayer Mini ready!"));
  myDFPlayer.volume(25);  // Set volume (0-30)

  // Play tracks in sequence
  myDFPlayer.play(1);  // Play track 0001.mp3
  delay(5000);         // Wait 5 seconds
  myDFPlayer.play(2);  // Play track 0002.mp3 
}

void loop() {
  // Nothing needed here for basic playback
}

The above code explains that the it is controlled with this DF Player mini module.It uses Software Serial on pins D3 for RX and D4 for TX to communicate with DF Player mini.

Under the setup function, the serial communication starts from 115200 baud rate with volume set to 25 out of 30.Firstly, it will play 0001.mp3 file and wait for 5 seconds and then play second i.e 0002.mp3 file.

The loop function is empty as playback was only once in setup.

I opened the Arduino IDE and installed the DF Player mini module library.

I opened new sketch and pasted my code.Then selected the board and port respectively.

Then i cliked to compile and upload the program, followed by clicking on serial monitor.The audio was detected and played.

Learning outcomes of the week

This week assignment has really helped me to understand the connections, power consumptions and the running a simple codes for output devices like mini speaker and mini water pump.This will help me to understand further as i go along with my final project as these devices are related.

Output devices like mini water pump requires a MOSFET or relay during the connections as it provides potential damage from high current flow to microcontroller.This regulates the proper switching.

Moreover, to play a audio by mini speaker, it requires the amplifier.DF Player mini module can work with such mini speakers to play mp3 audio.The DF Player mini worked with mini speaker as it has built-in amplifier.The mp3 audio file should be named like 0001, 0002 in four digits format and placed in a folder named MP3 in order to play play via micro SD card for DF player mini.The file name should match with the print file name while running the program.

Disclaimer: I have referred the codes from chatGPT and and made minor changes to codes.I have also referred from relevant sources.

Code files

Here is my Arduino IDE code files