STMPE2401 datasheet(21/55 Pages) STMICROELECTRONICS

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STMPE2401

Clocking system

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Clocking system

Figure 6.

Clocking system

The decision on clocks is based on the bits written into SYSCON registers. Bits 0 to 4 of the

SYSCON register control the gating of clocks to the Rotator, Keypad Controller, PWM and

GPIO respectively in the operational mode. When in sleep mode, the operating clock is cut

off from every functional blocks (including the I2C) except Keypad Controller and GPIO.

8.1

Programming sequence

To put the device in sleep mode, the following needs to be done by the host:

Write a ‘1’ to bit 4 of the SYSCON register.

To wakeup the device, the following needs to be done by the host:

Assert a wakeup routine on the I2C bus by sending the Start Bit, followed by the device

address and the R/W bit.

If there’s a NOACK, keep sending the wakeup routine till there is an ACK from the

slave.

To do a soft reset to the device, the host needs to do the following:

Write a ‘1’ to bit 7 of the SYSCON register.

This bit is automatically cleared upon reset.

To go into Hibernate mode, the following needs to be done by the host:

Set the Disable_32K bit to ‘1’

10. To come out of the Hibernate mode, the following needs to be done by the host:

11. Assert a system reset or

12. Put a wakeup on the I2C

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