Section 9 Timers
Rev. 7.00 Mar 10, 2005 page 264 of 652
REJ09B0042-0700
9.4.2 Register Descriptions
16-bit Timer Counter (TCF)
8-bit Timer Counter (TCFH)
8-bit Timer Counter (TCFL)
15 14 13 12 11 10 9 8
TCF
TCFH TCFL
76543210
0000000000000000
R/W
Bit:
Initial value:
Read/Write: R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W
TCF is a 16-bit read/write up-counter configured by cascaded connection of 8-bit timer counters
TCFH and TCFL. In addition to the use of TCF as a 16-bit counter with TCFH as the upper 8 bits
and TCFL as the lower 8 bits, TCFH and TCFL can also be used as independent 8-bit counters.
TCFH and TCFL can be read and written by the CPU, but when they are used in 16-bit mode, data
transfer to and from the CPU is performed via a temporary register (TEMP). For details of TEMP,
see section 9.4.3, CPU Interface.
TCFH and TCFL are each initialized to H'00 upon reset.
a. 16-bit mode (TCF)
When CKSH2 is cleared to 0 in TCRF, TCF operates as a 16-bit counter. The TCF input clock
is selected by bits CKSL2 to CKSL0 in TCRF.
TCF can be cleared in the event of a compare match by means of CCLRH in TCSRF.
When TCF overflows from H'FFFF to H'0000, OVFH is set to 1 in TCSRF. If OVIEH in
TCSRF is 1 at this time, IRRTFH is set to 1 in IRR2, and if IENTFH in IENR2 is 1, an
interrupt request is sent to the CPU.
b. 8-bit mode (TCFL/TCFH)
When CKSH2 is set to 1 in TCRF, TCFH, and TCFL operate as two independent 8-bit
counters. The TCFH (TCFL) input clock is selected by bits CKSH2 to CKSH0 (CKSL2 to
CKSL0) in TCRF.
TCFH (TCFL) can be cleared in the event of a compare match by means of CCLRH (CCLRL)
in TCSRF.
When TCFH (TCFL) overflows from H'FF to H'00, OVFH (OVFL) is set to 1 in TCSRF. If
OVIEH (OVIEL) in TCSRF is 1 at this time, IRRTFH (IRRTFL) is set to 1 in IRR2, and if
IENTFH (IENTFL) in IENR2 is 1, an interrupt request is sent to the CPU.
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