Datasheet

Section 12 Timer Z

Rev. 4.00 Mar. 15, 2006 Page 242 of 556

REJ09B0026-0400

Note on Clearing TSR Flag: When a specific flag in TSR is cleared, a combination of the BCLR

or MOV instructions is used to read 1 from the flag and then write 0 to the flag. However, if

another bit is set during this processing, the bit may also be cleared simultaneously. To avoid this,

the following processing that does not use the BCLR instruction must be executed. Note that this

note is only applied to the F-ZTAT version. This problem has already been solved in the mask

ROM version.

Example: When clearing bit 4 (OVF) in TSR

MOV.B @TSR,R0L

MOV.B #B'11101111, R0L Only the bit to be cleared is 0 and

the other bits are all set to 1.

MOV.B R0L,@TSR

Note on Writing to the TOA0 to TOD0 Bits and the TOA1 to TOD1 Bits in TOCR:

The TOA0 to TOD0 bits and the TOA1 to TOD1 bits in TOCR 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 FTIOA0 to FTIOD0 and FTIOA1 to FTIOD1 output, the

values of the FTIOA0 to FTIOD0 and FTIOA1 to FTIOD1 pin output and the values read from the

TOA0 to TOD0 and TOA1 to TOD1 bits may differ. Moreover, when the writing to TOCR and

the generation of the compare match A0 to D0 and A1 to D1 occur at the same timing, the writing

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

FTIOA0 to FTIOD0 and FTIOA1 to FTIOD1 pins. Therefore, when bit manipulation instruction is

used to write to TOCR, the values of the FTIOA0 to FTIOD0 and FTIOA1 to FTIOD1 pin output

may result in an unexpected result. When TOCR is to be written to while compare match is

operating, stop the counter once before accessing to TOCR, read the port 6 state to reflect the

values of FTIOA0 to FTIOD0 and FTIOA1 to FTIOD1 output, to TOA0 to TOD0 and TOA1 to

TOD1, and then restart the counter. Figure 12.59 shows an example when the compare match and

the bit manipulation instruction to TOCR occur at the same timing.