R8CSLASH20 datasheet(173/501 Pages) RENESAS

173 / 501 page

R8C/20 Group, R8C/21 Group

14. Timers

Rev.2.00 Aug 27, 2008

Page 157 of 458

REJ09B0250-0200

• Workaround example (b):

As shown in Figure 14.26 detect the start of the primary period by the TRBO pin output level and write to

registers TRBSC and TRBPR. These write operations must be completed by the beginning of period A.

If the port register’s bit value is read after the port direction register’s bit corresponding to the TRBO pin is

set to 0 (input mode), the read value indicates the TRBO pin output value.

Figure 14.26

Workaround Example (b) When TRBO Pin Output Value is Read

(3) To stop the timer counting in the primary period, use the TSTOP bit in the TRBCR register. In this case,

registers TRBPRE and TRBPR are initialized and their values are set to the values after reset.

14.2.5.3

Programmable one-shot generation mode

The following two workarounds should be performed in programmable one-shot generation mode.

(1) To write to registers TRBPRE and TRBPR during count operation (TCSTF bit is set to 1), note the

following points:

• When the TRBPRE register is written continuously during count operation (TCSTF bit is set to 1), allow

three or more cycles of the count source for each write interval.

• When the TRBPR register is written continuously during count operation (TCSTF bit is set to 1), allow

three or more cycles of the prescaler underflow for each write interval.

(2) Do not set both the TRBPRE and TRBPR registers to 00h.

TRBO pin output

Count source/

prescaler

underflow signal

Primary period

Period A

Read value of the port register’s

bit corresponding to the TRBO pin

(when the bit in the port direction

Secondary period

(i)

The TRBO output inversion

is detected at the end of the

secondary period.

Ensure sufficient time

Upon detecting (i), set the secondary and

then the primary register immediately.

(ii) (iii)

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