ST7265X datasheet(114/166 Pages) STMICROELECTRONICS

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ST7265x

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I²C SINGLE MASTER BUS INTERFACE (Cont’d)

11.7.7 Register Description

I2C CONTROL REGISTER (CR)

Read / Write

Reset Value: 0000 0000 (00h)

Bit 7:6 = Reserved. Forced to 0 by hardware.

Bit 5 = PE

Peripheral enable.

This bit is set and cleared by software.

0: Peripheral disabled

1: Master capability

Notes:

– When PE=0, all the bits of the CR register and

the SR register except the Stop bit are reset. All

outputs are released while PE=0

– When PE=1, the corresponding I/O pins are se-

lected by hardware as alternate functions.

– To enable the I2C interface, write the CR register

TWICE with PE=1 as the first write only activates

the interface (only PE is set).

Bit 4 = Reserved. Forced to 0 by hardware.

Bit 3 = START

Generation of a Start condition.

This bit is set and cleared by software. It is also

cleared by hardware when the interface is disa-

bled (PE=0) or when the Start condition is sent

(with interrupt generation if ITE=1).

– In master mode:

0: No start generation

1: Repeated start generation

– In idle mode:

0: No start generation

1: Start generation when the bus is free

Bit 2 = ACK

Acknowledge enable.

This bit is set and cleared by software. It is also

cleared by hardware when the interface is disa-

bled (PE=0).

0: No acknowledge returned

1: Acknowledge returned after a data byte is re-

ceived

Bit 1 = STOP

Generation of a Stop condition.

This bit is set and cleared by software. It is also

cleared by hardware when the interface is disa-

bled (PE=0) or when the Stop condition is sent.

– In Master mode only:

0: No stop generation

1: Stop generation after the current byte transfer

or after the current Start condition is sent.

Bit 0 = ITE

Interrupt enable.

This bit is set and cleared by software and cleared

by hardware when the interface is disabled

(PE=0).

0: Interrupts disabled

1: Interrupts enabled

Refer to Figure 4 for the relationship between the

events and the interrupt.

SCL is held low when the SB or BTF flags or an

EV2 event (See Figure 68) is detected.

START

ACK

STOP

ITE

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