HD6417660 RENESAS [Renesas Technology Corp], HD6417660 Datasheet - Page 284

• Manufacturer Part Number: HD6417660
• Description: Renesas 32-Bit RISC Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

9.4.6
RTCNT is an 8-bit counter register that increments using the clock selected by bits CKS2 to CKS0
in RTCSR. When RTCNT matches RTCOR, RTCNT is cleared to 0. The value in RTCNT returns
to 0 after counting up to 255. When the RTCNT is written, the upper 16 bits of the write data must
be H'A55A to cancel write protection.
Rev. 1.00, 02/04, page 246 of 804
Bit
2
1
0
Bit
31 to 8
7 to 0
Refresh Timer Counter (RTCNT)
Bit Name


Bit Name
RRC2
RRC1
RRC0
Initial
Value
0
0
0
Initial
Value
All 0
All 0
R/W Description
R/W
R/W
R/W
R/W Description
R/W Write Protection
R/W 8-bit Counter
These bits are always read as 0. When writing to these bits,
the upper 16-bit of the write data should be H'A55A to cancel
write protection. The lower 8-bit is should always be 0. If
other value is written to these bits, correct operation cannot
be guaranteed.
Refresh Count
Specify the number of continuous refresh cycles, when the
refresh request occurs after the coincidence of the values of
the refresh timer counter (RTCNT) and the refresh time
constant register (RTCOR). These bits can make the period
of occurrence of refresh long.
000: Once
001: Twice
010: 4 times
011: 6 times
100: 8 times
101: Setting prohibited
110: Setting prohibited
111: Setting prohibited