ST18952 datasheet(32/67 Pages) STMICROELECTRONICS

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ST18952

TSVR0-1: Timer start value register

(Address = 0059/005D, Reset value = 0000 h, Read/Write)

TUD

Timer up/down counting (bit 1)

•

When TUD = ‘0’, the TIM is counting ‘down’ (reset value), i.e. the TCVR current value

•

When TUD = ‘1’, the TIM is counting ‘up’, i.e. the TCVR current value register content

is incremented.

TLE

Timer load enable (bit 2)

•

When the counter has reached its end value (TCVR = TEVR), TCVR is (re)loaded

with TSVR (‘start value’) register content when TLE = ‘1’.

•

When TLE = ‘0’ (reset value), the next state of TCVR depends on the TCS bit.

TCS

Timer continue/stop (bit 3)

•

When TLE = ‘0’ (no load) and when the counter has reached its end value (TCVR =

TEVR), the TCVR content continues to increment/decrement according to TUD bit

when TCS = ‘1’ (continue mode).

•

When TCS = ‘0’ (stop mode - reset value), TCVR is stopped and content is frozen.

TIE

Timer interrupt enable (bit 4)

•

When the counter has reached its end value (TCVR = TEVR), an interrupt request is

generated on TIR output when TIE = ‘1’.

•

When TIE = ‘0’ (reset value), TIR output is disabled (=‘1’).

TCM

Timer cock mode (bit 5)

•

When TCM = ‘0’ (reset value), the TCVR clock is derived from internal MCLK clock

according to TFP bits.

•

When TCM = ‘1’, the TCVR clock is the external ECLK clock.

TFP(3:0)

Timer frequency prescaler (bits 9-4; TFP(3) = msb)

•

When TCM = ‘0’ (internal clock), the TCVR register clock is derived from the MCLK

clock input by dividing MCLK by 2(2+ TFP).

The coding is as follows:

TFP = 0h

prescaler by 2 (reset value) MCLK divided by 4

TFP = 1h

prescaler by 4 MCLK divided by 8

TFP = 2h

prescaler by 8 MCLK divided by 16

-...

TFP = Fh

prescaler by 216MCLK divided by 217

Bits 10-11

RESERVED and must be written as’0’

Bits 12-15

Unused and read as’0’

9876

3210

TSV

Bit

Function

TSV(15:0)

Timer start value (bits15-0, TSV15 is msb

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