ST7LITEUSX datasheet(40/108 Pages) STMICROELECTRONICS

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ST7LITEUSx

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POWER SAVING MODES (Cont’d)

8.5.1 Register Description

AWUFH CONTROL/STATUS REGISTER

(AWUCSR)

Read/Write

Reset Value: 0000 0000 (00h)

Bits 7:3 = Reserved.

Bit 2= AWUF Auto Wake Up Flag

This bit is set by hardware when the AWU module

generates an interrupt and cleared by software on

reading AWUCSR. Writing to this bit does not

change its value.

0: No AWU interrupt occurred

1: AWU interrupt occurred

Bit 1= AWUM Auto Wake Up Measurement

This bit enables the AWU RC oscillator and con-

nects its output to the input capture of the 8-bit Lite

timer. This allows the timer to be used to measure

the AWU RC oscillator dispersion and then com-

pensate this dispersion by providing the right value

in the AWUPRE register.

0: Measurement disabled

1: Measurement enabled

Bit 0 = AWUEN Auto Wake Up From Halt Enabled

This bit enables the Auto Wake Up From Halt fea-

ture: once HALT mode is entered, the AWUFH

wakes up the microcontroller after a time delay de-

pendent on the AWU prescaler value. It is set and

cleared by software.

0: AWUFH (Auto Wake Up From Halt) mode disa-

bled

1: AWUFH (Auto Wake Up From Halt) mode ena-

bled

Note: whatever the clock source, this bit should be

set to enable the AWUFH mode once the HALT in-

struction has been executed.

AWUFH PRESCALER REGISTER (AWUPR)

Read/Write

Reset Value: 1111 1111 (FFh)

Bits 7:0= AWUPR[7:0] Auto Wake Up Prescaler

These 8 bits define the AWUPR Dividing factor (as

explained below:

In AWU mode, the period that the MCU stays in

Halt Mode (tAWU in Figure 26 on page 38) is de-

fined by

This prescaler register can be programmed to

modify the time that the MCU stays in Halt mode

before waking up automatically.

Note: If 00h is written to AWUPR, depending on

the product, an interrupt is generated immediately

after a HALT instruction, or the AWUPR remains

unchanged.

Table 11. AWU Register Map and Reset Values

000

AWU

PR7

AWU

PR6

AWU

PR5

AWU

PR4

AWU

PR3

AWU

PR2

AWU

PR1

AWU

PR0

AWUPR[7:0

]

Dividing factor

00h

Forbidden

01h

...

FEh

254

FFh

255

AWU

AWUPR

AWURC

--------------------------t

RCSTRT

Address

(Hex.)

Label

76543

210

0049h

AWUPR

Reset Value

AWUPR7

AWUPR6

AWUPR5

AWUPR4

AWUPR3

AWUPR2

AWUPR1

AWUPR0

004Ah

AWUCSR

Reset Value

00000

AWUF

AWUM

AWUEN

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