STMPE801 datasheet(14/26 Pages) STMICROELECTRONICS

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Turning I2C block OFF and ON

STMPE801

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5.11

General call

A general call address is a transaction with the slave address of 0x00 and R/W = 0. When a

general call address is made, the device responds to this transaction with an

acknowledgement and behaves as a slave-receiver mode. The meaning of a general call

address is defined in the second byte sent by the master-transmitter.

Note:

All other second byte value will be ignored.

Turning I2C block OFF and ON

STMPE801 operates entirely on the I2C clock. When there are no activity on the I2C bus,

current consumption of the device is extremely low. However, when there are activity on the

I2C bus, current consumption increases, even if the I2C traffic is not directed to the assigned

address.

Host system may choose to shut-down the I2C block in the STMPE801, if no access to the

registers are required. This feature allows the current consumption to drop to the minimum.

Host system turns OFF the I2C block by writing ‘1’ into the I2C_SHDN bit. The I2C block will

shut down on the next valid clock edge of the I2C clock signal. In this state, the device

CANNOT be accessed by I2C, as the I2C has shut down completely.

To turn ON the I2C block, system host must reset the STMPE801 in order to re-activate the

I2C block. This could be done by hardware assertion of the RESET pin.

Table 9. General call

R/W

Second Byte Value

Definition

0x06

2-byte transaction in which the second byte tells the slave device

to reset and write (or latch in) the 1-bit programmable part of the

slave address.

0x04

2-byte transaction in which the second byte tells the slave device

not to reset and write (or latch in) the 1-bit programmable part of

the slave address.

0x00

Not allowed as second byte.

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