HD64F36022 datasheet(191/384 Pages) RENESAS

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Section 11 Timer W

Rev. 4.00 Sep. 23, 2005 Page 165 of 354

REJ09B0025-0400

5. The TOA to TOD bits in TCRW decide the value of the FTIO pin, which is output until the

first compare match occurs. Once a compare match occurs and this compare match changes the

values of FTIOA to FTIOD output, the values of the FTIOA to FTIOD pin output and the

values read from the TOA to TOD bits may differ. Moreover, when the writing to TCRW and

the generation of the compare match A to D occur at the same timing, the writing to TCRW

has the priority. Thus, output change due to the compare match is not reflected to the FTIOA

to FTIOD pins. Therefore, when bit manipulation instruction is used to write to TCRW, the

values of the FTIOA to FTIOD pin output may result in an unexpected result. When TCRW is

to be written to while compare match is operating, stop the counter once before accessing to

TCRW, read the port 8 state to reflect the values of FTIOA to FTIOD output, to TOA to TOD,

and then restart the counter. Figure 11.26 shows an example when the compare match and the

bit manipulation instruction to TCRW occur at the same timing.

Compare match

signal B

FTIOB pin

TCRW

write signal

Set value

Bit

TCRW

CCLR

CKS2

CKS1

CKS0

TOD

TOC

TOB

43210

TOA

Expected output

Remains high because the 1 writing to TOB has priority

TCRW has been set to H'06. Compare match B and compare match C are used. The FTIOB pin is in the 1 output state,

and is set to the toggle output or the 0 output by compare match B.

When BCLR#2, @TCRW is executed to clear the TOC bit (the FTIOC signal is low) and compare match B occurs

at the same timing as shown below, the H'02 writing to TCRW has priority and compare match B does not drive the FTIOB signal low;

the FTIOB signal remains high.

BCLR#2, @TCRW

(1) TCRW read operation: Read H'06

(2) Modify operation: Modify H'06 to H'02

(3) Write operation to TCRW: Write H'02

Figure 11.26 When Compare Match and Bit Manipulation Instruction to TCRW

Occur at the Same Timing

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