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I2C Communication

1. Features

- 2 Signals

1) SDA (Serial Data): Signal to transmit

2) SCL (Serial Clock): Signal to synchronize Master and Slave

- Control devices by combination of SDA and SCL

- SDA's Default: 1(Pull-up)

* Once communication gets started, SDA should be changed while SCL is zero.

Because, Master and Slave are synchronized.

- SCL Packet: 9 bit (7 bit: Address + 2 bit: R/W)

- Data Packet: 9 bit (8 bit: Data + 1 bit: ACK)

* ACK is to check if data is received well.

2. General Flow

Communication starts -> Address Packet -> Data Packet -> Stop communication

3. Advantages

1) Be able to control devices with only 2 signal wires

-> Devices have to have different address (Transmitted by 'packet')

2) 1:N Communication

-> One Master chip can manage several Slave chips paralleled.

3) Synchronized communication

-> I2C Communication is not much dependent on the time unlike RS232C.

-> Even if timing is not exactly matched, data signal could be adjusted along the clock signal.

* 관련 레지스터 공부가 필요!

1. Compile

Act of turning human-readable code into the machine-understandable code.

2. Debug (=get rid of bugs)

Act of finding where the application is going wrong in the code.

3. UART (Universal Asynchronous Receiver/Transmitter) (범용 비동기 시리얼통신)

1) Serial(직렬) Communication

2) The method that transmits the data every certain period sequentially.

(데이터를 특정시간 간격으로 순차적으로 보내는 통신 방법)

(병렬통신: 한 번에 한 의미의 데이터를 보내는 통신 방법)

(장점: 병렬 통신보다 선을 적게 사용한다)

3) The communication that does not need synchronous signals.

-> Therefore, the protocol has to be set up.

* Protocol: 컴퓨터 간에 정보를 주고 받을 때 통신방법에 대한 규칙과 약속(어떻게 통신을 하겠다)

  4) UART has “start bit” and “stop bit” that tell the other computer whether it’s started or stopped.

  5) The speed of communication [bps/sec]

Ex) Data bit: 8 bit / Speed: 1 bps

-> It will last for 8 secs and end with “stop bit”.

(1초 간격으로 1비트씩 8초가 걸려 데이터가 전송되고 정지비트로 끝난다)

4. JTAG (Joint Test Action Group)

1) To test if PCB or IC devices which are built work well

2) The usage of JTAG is similar to USB Port

-> However, because the speed of communication is highly slow, it is used mostly for check if devices work fine.