STMPE1601 datasheet(20/61 Pages) STMICROELECTRONICS

20 / 61 page

System controller

STMPE1601

20/61

7.1

States of operation

Figure 4.

Modes of operation

The device has three main modes of operation:

●

Operational mode: This is the mode, whereby normal operation of the device takes

place. In this mode, the RC clock is available and the main FSM unit routes this clock

and the 32 KHz clock to all the device blocks that are enabled. In this mode, individual

blocks that need not to

be working can be turned off by the master by programming the bits 3 to 0 of the

SYS_CTRL register.

●

Sleep mode: In this low-power mode, the RC oscillator is powered down. All the blocks

which need clocks derived from the 32KHz clock will continue getting a 32 KHz clock.

In this mode also, iindividual blocks can be turned off by the master by programming

the bits 3 to 0 of the SYS_CTRL register. However, the master needs to program the

SYS_CTRL register before coming into this mode, as in the sleep mode, the IIC

interface is not active except to detect traffic for wakeup. Any activity on the I2C port

(intended I2C transaction for the device) or Wakeup pin or Hotkey activity will cause the

device to leave this mode and go into the Operational mode. When leaving this mode,

the I2C will need to hold the SCLK till the RC clock is ready.

●

Hibernate mode: This mode is entered when the system writes a ‘1’ to bit 5 of the

SYS_CTRL register. In this mode, the device is completely inactive as there is

absolutely no clock. Only a Reset or a wakeup on IIC will bring back the System to

operational mode. A keypress detect will bring the system to Sleep mode, in which the

debounce of the key will take place.

Note:

The 32 kHz clock mentioned in this section can be (1) an externally fed 32 KHz clock, or (2)

an internally generated (from RC OSC) clock. In case the internal clock is used, the clock

has a range of 25 to 45 KHz.

OPERATIONAL

SLEEP

Set Disable_32K bit

Reset

HIBERNATE

32K: OFF

RC: OFF

Set Sleep bit

or autosleep

Valid Keypress

detect

C transaction

Keypad, Interrupts

I C transaction

32K: ON

RC: OFF

32K: ON

RC: OFF

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