Interface With The Cpu - Renesas F-ZTAT H8 Series Hardware Manual

Bit 2—Compare Match Flag L (CMFL): Bit 2 is a status flag indicating a compare match
between TCFL and OCRFL. This flag is set by hardware and cleared by software. It cannot be set
by software.
Bit 2: CMFL Description
0 Clearing condition:
After reading CMFL = 1, cleared by writing 0 to CMFL
1 Setting condition:
Set when the TCFL value matches the OCRFL value
Bit 1—Timer Overflow Interrupt Enable L (OVIEL): Bit 1 enables or disables TCFL overflow
interrupts.
Bit 1: OVIEL Description
0 TCFL overflow interrupt disabled
1 TCFL overflow interrupt enabled
Bit 0—Counter Clear L (CCLRL): Bit 0 selects whether or not TCFL is cleared when a
compare match occurs between TCFL and OCRFL.
Bit 0: CCLRL Description
0 TCFL clearing by compare match disabled
1 TCFL clearing by compare match enabled
9.5.3

Interface with the CPU

TCF and OCRF are 16-bit read/write registers, whereas the data bus between the CPU and on-chip
peripheral modules has an 8-bit width. For this reason, when the CPU accesses TCF or OCRF, it
makes use of an 8-bit temporary register (TEMP).
In 16-bit mode, when reading or writing TCF or writing OCRF, always use two consecutive byte
size MOV instructions, and always access the upper byte first. Data will not be transferred
properly if only the upper byte or only the lower byte is accessed. In 8-bit mode there is no such
restriction on the order of access.
Write Access: When the upper byte is written, the upper-byte data is loaded into the TEMP
register. Next when the lower byte is written, the data in TEMP goes to the upper byte of the
register, and the lower-byte data goes directly to the lower byte of the register. Figure 9.5 shows a
TCF write operation when H'AA55 is written to TCF.
Rev.3.00 Jul. 19, 2007 page 235 of 532
9. Timers
(initial value)
(initial value)
(initial value)
REJ09B0397-0300