HD64F36049 datasheet(244/562 Pages) RENESAS

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Section 13 Timer W

Rev. 3.00 Mar. 15, 2006 Page 212 of 526

REJ09B0060-0300

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 13.26 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

0110

3210

CCLR

CKS2

CKS1

CKS0

TOD

TOC

TOB

TOA

Expected

output

Remains high because the 1 writing to TOB has priority

TOCR 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, @TOCR is executed to clear the TOC bit (the FTIOC0 signal is low) and compare match B

occurs at the same timing as shown below, the H'02 writing to TOCR 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 TOCR: Write H'02

Figure 13.26 When Compare Match and Bit Manipulation Instruction to TCRW

Occur at the Same Timing

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