PC912XDP512F0CFVR datasheet(343/1348 Pages) FREESCALE

343 / 1348 page

Chapter 7 Enhanced Capture Timer (S12ECT16B8CV2)

MC9S12XDP512 Data Sheet, Rev. 2.21

Freescale Semiconductor

343

7.3.2.25

Precision Timer Prescaler Select Register (PTPSR)

Read: Anytime

Write: Anytime

All bits reset to zero.

LATQ

Input Control Latch or Queue Mode Enable — The BUFEN control bit should be set in order to enable the IC

and pulse accumulators holding registers. Otherwise LATQ latching modes are disabled.

Write one into ICLAT bit in MCCTL, when LATQ and BUFEN are set will produce latching of input capture and

pulse accumulators registers into their holding registers.

0 Queue mode of Input Capture is enabled. The main timer value is memorized in the IC register by a valid input

pin transition. With a new occurrence of a capture, the value of the IC register will be transferred to its holding

1 Latch mode is enabled. Latching function occurs when modulus down-counter reaches zero or a zero is

written into the count register MCCNT (see Section 7.4.1.1.2, “Buffered IC Channels”). With a latching event

the contents of IC registers and 8-bit pulse accumulators are transferred to their holding registers. 8-bit pulse

accumulators are cleared.

76543210

PTPS7

PTPS6

PTPS5

PTPS4

PTPS3

PTPS2

PTPS1

PTPS0

Reset

00000000

Figure 7-47. Precision Timer Prescaler Select Register (PTPSR)

Table 7-31. PTPSR Field Descriptions

Field

Description

7:0

PTPS[7:0]

Precision Timer Prescaler Select Bits — These eight bits specify the division rate of the main Timer prescaler.

These are effective only when the PRNT bit of TSCR1 is set to 1. Table 7-32 shows some selection examples in

this case.

The newly selected prescale factor will not take effect until the next synchronized edge where all prescale counter

stages equal zero.

Table 7-32. Precision Timer Prescaler Selection Examples when PRNT = 1

PTPS7

PTPS6

PTPS5

PTPS4

PTPS3

PTPS2

PTPS1

PTPS0

Prescale

Factor

00000000

00000001

00000010

00000011

00000100

00000101

00000110

Table 7-30. ICSYS Field Descriptions (continued)

Field

Description

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