M16C1N datasheet(88/238 Pages) RENESAS

88 / 238 page

Rev.1.00

Oct 20, 2004

page 76 of 222

M16C/1N Group

12. Timers

REJ09B0007-0100Z

Note 1: In the pulse output mode, the direction register of port P17 must be set to input.

Note 2: This bit should rewrite with inhibiting the CNTR0 interrupt. To use this interrupt, enable an interrupt after the

CNTR0 interrupt request bit is cleared with the MOV instruction.

Note 3: Output is set regardless of the setting of the direction register of port P30.

b5 b4

Timer X mode register

TXMOD0

TXMOD1

Operation mode

select bit 0, 1

(Note 2)

0 1 : Pulse output mode (Note 1)

R0EDG

CNTR0 polarity

switching bit (Note 2)

0 : Output starts at "H" (Interrupt at rising edge)

1 : Output starts at "L" (Interrupt at falling edge)

TXS

Timer X count

start flag

0 : Stops counting

1 : Starts counting

TXOCNT

P30/TXOUT

select bit

Operation mode

select bit 2

TXMOD2

0 : Set to "0" in pulse output mode

0 : Port P30

1 : TXOUT output (Note 3)

Symbol

TXMR

Address

008B16

When reset

0016

Function

Bit name

Bit symbol

b1 b0

TXEDG

Effectual edge

reception flag

TXUND

Timer X under

flow flag

Invalid in pulse output mode.

When write, set "0". When read, this contents

is indeterminate.

Invalid in pulse output mode.

When write, set "0". When read, this contents

is indeterminate.

(n+1) X (m+1)

Item

Specification

Count source

f1, f8, f32, fC32

Count operation

• Down count

• When the timer underflows, it reloads the reload register contents before continuing counting

Divide ratio

n: Set value of Prescaler X, m: Set value of Timer X

Count start condition

Count start flag is set (=1)

Count stop condition

Count start flag is reset (=0)

Interrupt request generation timing • When Timer X underflows [Timer X interruption]

• Rising (R0EDG=0) or falling (R0EDG=1) of CNTR0 output [CNTR0 interruption]

CNTR0 pin function

Pulse output

TXOUT pin function

Programmable I/O port or pulse output (Inverted waveform of the pulse output from the

CNTR0 pin)

Read from timer

Count value can be read out by reading Timer X register.

Same applies to Prescaler X register.

Write to timer

When a value is written to Timer X register, it is written to both reload register and counter.

Same applies to Prescaler X register.

Select function

• Pulse output function

Each time the timer underflows, the TXOUT pin’s polarity is reversed

• CNTR0 polarity switching function

The polarity level at starting of pulse output can be selected to be "High" or "Low" with software.

12.2.2 Pulse Output Mode

In this mode, the timer counts an internally generated count source, and outputs from the CNTR0 pin

a pulse whose polarity is inverted each time the timer underflows.

(See Table 12.4) Figure 12.7 shows Timer X mode register in pulse output mode.

Table 12.4 Specifications of pulse output mode

Figure 12.7 Timer X mode register in pulse output mode

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