STCF03 datasheet(16/35 Pages) STMICROELECTRONICS

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Introduction

STCF03

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7.7

Acknowledge

The master (µP) puts a resistive HIGH level on the SDA line during the acknowledge clock

pulse (see Figure 7). The peripheral (STCF03) that acknowledges has to pull-down (LOW)

the SDA line during the acknowledge clock pulse, so that the SDA line is stable LOW during

this clock pulse. The peripheral which has been addressed has to generate an acknowledge

pulse after the reception of each byte, otherwise the SDA line remains at the HIGH level

during the ninth clock pulse duration. In this case the master transmitter can generate the

STOP information in order to abort the transfer. The STCF03 won't generate the

acknowledge if the VI supply is below the undervoltage lockout threshold.

7.8

Writing to a single register

Writing to a single register starts with a START bit followed by the 7 bit device address of

STCF03. The 8th bit is the R/W bit, which is 0 in this case. R/W = 1 means a reading

operation. Then the master waits for an acknowledge from STCF03. Then the 8 bit address

of register is sent to STCF03. It is also followed by an acknowledge pulse. The last

transmitted byte is the data that is going to be written to the register. It is again followed by

an acknowledge pulse from STCF03. Then master generates a STOP bit and the

communication is over. See Figure 8 below.

Figure 7.

Acknowledge on I2C Bus

Table 8. Interface protocol

Device address + R/W bit

Data

765

3210

765

321

STCF03 Datasheet(PDF) 16 Page - STMicroelectronics