Mater Device Sends Start Condition To All Slaves.


Specifications

Power supply: 5VDC.

Detection distance: 3 - 80cm.

Output current: 300mA.

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The open collector NPN output helps to customize the output voltage, the higher the resistance, the higher the output voltage.

Has red LED display.

Size: 1.8cm (L) x 7.0cm (L).

Schematic diagram


Figure 1.19. Schematic diagram of infrared sensor E18-D80NK.

Working principle: Infrared rays emit a certain frequency, when detecting an obstacle in the transmission direction (reflecting surface), it reflects into the infrared receiver light, after comparison the blue light will light up, at the same time a digital signal is sent to the output (a low-level signal).

Effective working distance from 20 to 150 cm, working voltage is 3.3V to 5V. The light sensitivity of the sensor is adjusted by pressure, the sensor is easy to assemble and easy to use.

1.4.2.3. 1 channel 5V relay module.

1-channel 5V Relay Module includes 1 relay with operating voltage at 5VDC, maximum control output at 250V 10A for AC voltage and 30V for DC voltage.


Figure 1.20. 1-channel 5V relay module.

Professional compact 1-channel relay module, good anti-interference ability and good insulation ability. The module has a built-in relay trigger circuit using optical isolation IC and transistor to completely isolate the microcontroller circuit from the relay, ensuring stable operation of the microcontroller.

This 1-channel relay control circuit uses a high-level trigger pin (5V). When there is a 5V signal on the IN pin, the relay will jump to the normally open state of the Relay.

Specifications.

- Maximum load voltage: AC 250V-10A / DC 30V-10A.

- Control voltage: 5VDC.

- Relay trigger current: 5mA.

- Trigger state: High level.

- Size: 50*26*18.5 mm.

Function of the pins of the relay module.

VCC: provides optimal voltage to this pin.

GND: connect to the power source.

S: connect signal pin, depending on the relay module, it has different tasks.

COM: connect to any pin of the electrical device.

ON or NO: connect to the hot pin if using AC power source and positive pole if using DC power source.

OFF or NC: connect the cold pin if using AC power and the negative pole if using DC power.


1.4.2.4. 16X2 LCD screen.


Figure 1.21. 16x2 LCD screen.

16x2 LCD is used to display status or parameters.

- LCD 16x2 has 16 pins including 8 data pins (D0 – D7) and 3 control pins (RS, RW, EN).

- The remaining 5 pins are used to supply power and backlight to the 16x2 LCD.

- The control pins help us easily configure the LCD in command mode or data mode, they also help us configure it in read or write mode.

- LCD 16x2 can also be used in 4 bit or 8 bit mode depending on the application we are doing.

Specifications.

- Operating voltage: 2.5 – 6v DC.

- Supported screens: LCD1602, 1604, 2004 (driver HD44780).

- Communication: l2C.

- Default address: 0x27 (can be adjusted by short-circuiting pin A0/A1/A2.

- Integrated jump pin to provide light for LCD or short.

- Integrated contrast adjustment potentiometer for LCD.

1.4.2.5. I2C communication standard.

I2C is the abbreviation of the English phrase “Inter – Integrated Circuit”. It is a communication protocol developed by Philips Semiconductors to transmit data between a central processor and multiple ICs on the same circuit board using only two signal lines.


This is a synchronous serial communication protocol. It means that data bits are transmitted one by one at regular intervals set by a reference clock signal.

Data is transmitted between the Master and Slave devices via a single SDA data line, through structured strings of 0s and 1s (bits). Each string of 0s and 1s is called a transaction, and the data in each transaction is structured as follows:

Figure 1.22. Structure in each transaction.

Start Condition.

Whenever a master device/IC decides to initiate a transaction, it will switch the SDA line from high voltage to low voltage before the SCL line switches from high to low.

When the start condition is sent by the Master device, all Slave devices become active even if they are in sleep mode and waiting for the address bit.

Figure 1.23. Starting conditions.

Address block

It consists of 7 bits and is filled with the address of the Slave device from which the Master device needs to send/receive data. All the Slave devices on the I2C bus compare these address bits with their addresses.



arrive

Bit Read / Write

This bit determines the direction of data transmission. If the Master/IC device needs to send data

Slave device, this bit is set to „0‟. If the IC/Master needs to receive data from the Slave device, this bit is set to „1‟.

ACK/NACK Bits

ACK / NACK stands for Acknowledged/Not-Acknowledged. If the physical address of any Slave device matches the address transmitted by the Master device, the value of this bit is set to „0‟ by the Slave device. Otherwise, it remains at logic „1‟ (default).

Data block

It consists of 8 bits and they are set by the sender, with the data bits to be transmitted.

to the receiver. This block is followed by an ACK/NACK bit and is set to „0‟ by the receiver if it successfully receives the data. Otherwise, it remains at logic „1‟.

The combination of data block followed by ACK/NACK bit is repeated until the data transmission is completed.

Stop Condition

After the required data frames are transmitted over the SDA line, the Master device transitions the SDA line from low voltage to high voltage before the SCL line transitions from high to low.

Figure 1.24. Termination condition.

How it works.

- The Master device sends the start condition to all Slave devices.


- The Master device sends the 7-bit address of the Slave device that the Master device wants to communicate with along with the Read/Write bit.

Figure 1.25. Mater device sends start condition to all Slaves.

Each Slave device compares the address sent from the Master device to its own address. If the addresses match, the Slave device sends back an ACK bit by pulling the SDA line low and the ACK / NACK bit is set to „0‟. If the address from the Master device does not match the Slave device’s own address, the SDA line is high and the ACK / NACK bit is set to „1‟ (default).

Figure 1.26. Slaves compare the address sent by the Master.


The Master device sends or receives data frames. If the Master device wants to send data to the Slave device, the Read/Write bit is low. If the Master device is receiving data from the Slave device, this bit is high.

Figure 1.27. Master device sends or receives data frames.

If the data frame is successfully received by the Slave device, it will set the ACK/NACK bit to „0‟, signaling the Master device to continue.

Figure 1.28. Slave device successfully receives data frame.


After all data is sent to the Slave device, the Master device sends a stop condition to signal all Slave devices that the data transmission has ended.

Figure 1.29. The Master device sends a stop condition, ending data transmission.

1.4.2.6. Buzzer.

5VDC Buzzer has long life, stable performance, good quality, compact production suitable for design with compact buzzer circuits, alarm circuits.


Figure 1.30. Buzzer.

Specifications.

- Power: 3.5V - 5.5V.

- Current consumption: <25mA.

- Sound amplitude: >80 dB.

- Operating temperature: -20 °C to +70 °C.

- Size: Diameter 12mm, height 9.7mm.

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