ST7585 datasheet(13/51 Pages) SITRONIX

13 / 51 page

ST7585

Ver 1.0c

13/51

2009/04/14

2C Interface

The I

2C Interface is for bi-directional, two-line communication between different ICs or modules. The two lines are a Serial

Data line (SDA) and a Serial Clock line (SCLK). Both lines must be connected with a pull-up resistor which drives SDA and

SCLK to high when the bus is not busy. Data transfer can be initiated only when the bus is not busy.

The I

2C interface of ST7585 supports write access and read of acknowledge-bit. The I2C interface receives and executes

the commands sent via the I

2C Interface. It also receives RAM data and sends it to the Display RAM.

BIT TRANSFER

One data bit is transferred during each clock pulse. The data on SDA line must remain stable during the HIGH period of the

clock pulse because changes of SDA line at this time will be interpreted as START or STOP condition. Refer to Fig 5.

Fig 5.

Bit transfer

START AND STOP CONDITIONS

Both SDA and SCLK lines remain HIGH when the bus is not busy. A HIGH-to-LOW transition of SDA, while SCLK is HIGH

is defined as the START condition (S). A LOW-to-HIGH transition of SDA while SCLK is HIGH is defined as the STOP

condition (P). The START and STOP conditions are illustrated in Fig 6.

Fig 6.

Definition of START and STOP conditions

SYSTEM CONFIGURATION

The system configuration is illustrated in Fig 7 and some word-definitions are explained below:

- Transmitter: the device which sends the data to the bus.

- Receiver: the device which receives the data from the bus.

- Master: the device, which initiates a transfer, generates clock signals and terminates a transfer.

- Slave: the device which is addressed by a master.

- Multi-Master: more than one master can attempt to control the bus at the same time without corrupting the message.

- Arbitration: the procedure to ensure that, if more than one master tries to control the bus simultaneously, only one is

allowed to do so and the message is not corrupted.

- Synchronization: procedure to synchronize the clock signals of two or more devices.

ST7585 Datasheet(PDF) 13 Page - Sitronix Technology Co., Ltd.