M16CSLASH29 datasheet(144/499 Pages) RENESAS

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12. Timer B

page 120

Item

Specification

Count source

• External signals input to TBiIN pin (i=0 to 2) (effective edge can be selected

in program)

• Timer Bj overflow or underflow (j=i-1, except j=2 if i=0)

Count operation

• Decrement

• When the timer underflows, it reloads the reload register contents and

continues counting

Divide ratio

1/(n+1)

n: set value of TBi register

000016 to FFFF16

Count start condition

Set TBiS bit(1) to 1 (start counting)

Count stop condition

Set TBiS bit to 0 (stop counting)

Interrupt request generation timing Timer underflow

TBiIN pin function

Count source input

Read from timer

Count value can be read by reading TBi register

Write to timer

• When not counting and until the 1st count source is input after counting start

Value written to TBi register is written to both reload register and counter

• When counting (after 1st count source input)

Value written to TBi register is written to only reload register

(Transferred to counter when reloaded next)

NOTE:

1. Bits TB2S to TB0S are assigned to the bit 7 to bit 5 in the TABSR register.

12.2.2 Event Counter Mode

In event counter mode, the timer counts pulses from an external device or overflows and underflows of

other timers (see Table 12.7). Figure 12.19 shows the TBiMR register in event counter mode.

Table 12.7 Specifications in Event Counter Mode

Figure 12.19 TBiMR Register in Event Counter Mode

Timer Bi Mode Register (i=0 to 2)

Symbol

Address

After Reset

TB0MR to TB2MR

039B16 to 039D16

00XX00002

Bit Name

Function

Bit Symbol

b7 b6 b5 b4 b3 b2 b1 b0

Operation mode select bit

0 1: Event counter mode

b1 b0

TMOD1

TMOD0

MR0

Count polarity select

bit (1)

MR2

MR1

MR3

TCK1

TCK0

0 0: Counts external signal's

falling edges

0 1: Counts external signal's rising

edges

1 0: Counts external signal's

falling and rising edges

1 1: Do not set

b3 b2

NOTES:

1. Effective when the TCK1 bit is set to 0 (input from TBiIN pin). If the TCK1 bit is set to 1 (TBj overflow or

underflow), these bits can be set to 0 or 1.

2. The port direction bit for the TBiIN pin must be set to 0 (= input mode).

No effect in event counter mode

Can be set to 0 or 1

Event clock select

0 : Input from TBiIN pin (2)

1 : TBj overflow or underflow

(j = i – 1, except j = 2 if i = 0)

TB0MR register

Set to 0 in timer mode

TB1MR, TB2MR registers

Nothing is assigned. If necessary, set to 0. When read, the

content is undefined

When write in event counter mode, set to 0. When read in event

counter mode, its content is undefined

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