R8CSLASH15 datasheet(107/277 Pages) RENESAS

107 / 277 page

R8C/14 Group, R8C/15 Group

13. Timers

Rev.2.10

Jan 19, 2006

Page 95 of 253

REJ09B0164-0210

13.1.5

Pulse Period Measurement Mode

Pulse period measurement mode is mode to measure the pulse period of an external signal which

inputs from the INT1/CNTR0 pin (See Table 13.6 Specification of Pulse Period Measurement

Mode). Figure 13.9 shows the TXMR Register in Pulse Period Measurement Mode. Figure 13.10

shows an Operating Example in Pulse Period Measurement Mode.

NOTES:

1. Input the pulse whose period is longer than twice of the prescaler X period. Input the longer pulse for

“H” width and “L” width than the prescaler X period. If the shorter pulse than the period is input to the

CNTR0 pin, the input may be disabled.

Table 13.6

Specification of Pulse Period Measurement Mode

Item

Specification

Count Source

f1, f2, f8, fRING

Count Operation

• Decrement

• After an active edge of measurement pulse is input, contents for the read-out

buffer are retained at the first underflow of prescaler X. Then timer X reloads

contents in the reload register at the second underflow of prescaler X and

continues counting.

Count Start Condition

Write “1” (count start) to the TXS bit in the TXMR register

Count Stop Condition

Write “0” (count stop) to TXS bit in TXMR register

Interrupt Request

Generation Timing

• When timer X underflows or reloads [timer X interrupt]

• Rising or falling of CNTR0 input (end of measurement period) [INT1 interrupt]

INT10/CNTR00,

INT11/CNTR01 Pin

Function

Measurement pulse input(1) (INT1 interrupt input)

CNTR0 Pin Function

Programmable I/O port

Read from Timer

Contents in the read-out buffer can be read by reading the TX register. The

value retained in the read-out buffer is released by reading TX register.

Write to Timer

• When writing to the TX and PREX registers while the count stops, the value

is written to both the reload register and counter.

• When writing to the TX and PREX registers during the count, the value is

written to each reload register of the TX and PREX registers at the following

count source input and the data is transferred to the counter at the second

count source input and the count re-starts at the third count source input.

Select Function

•INT1/CNTR0 polarity switch function

The R0EDG bit can select the measurement period of input pulse.

• Measurement pulse input pin select function

The CNTRSEL bit in the UCON register can select the CNTR00 or CNTR01

pin.

R8C/15 Datasheet(PDF) 107 Page - Renesas Technology Corp

R8C/15 Datasheet(HTML) 107 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL