340
•
Bit 7 (Watchdog Timer Overflow (WOVF)): WOVF indicates that TCNT has overflowed
(from H'FF to H'00) in watchdog timer mode. It is not set in interval timer mode.
Bit 7: WOVF
Description
0
No TCNT overflow in watchdog timer mode
(Initial value)
Cleared when software reads WOVF, then writes 0 in WOVF
1
Set by TCNT overflow in watchdog timer mode
•
Bit 6 (Reset Enable (RSTE)): RSTE selects whether to reset the chip internally if the TCNT
overflows in watchdog timer mode.
Bit 6: RSTE
Description
0
Not reset when TCNT overflows
(Initial value)
LSI not reset internally, but TCNT and TCSR reset within WDT.
1
Reset when TCNT overflows
•
Bit 5 (Reset Select (RSTS)): RSTS selects the type of internal reset generated if TCNT
overflows in watchdog timer mode.
Bit 5: RSTS
Description
0
Power-on reset
(Initial value)
1
Manual reset
•
Bits 4–0 (Reserved): These bits are always read as 1. The write value should always be 1.
12.2.4Notes on Register Access
The watchdog timer’s TCNT, TCSR, and RSTCSR registers differ from other registers in that they
are more difficult to write. The procedures for writing and reading these registers are given below.
Writing to TCNT and TCSR: These registers must be written by a word transfer instruction.
They cannot be written by byte transfer instructions. TCNT and TCSR both have the same write
address. The write data must be contained in the lower byte of the written word. The upper byte
must be H'5A (for TCNT) or H'A5 (for TCSR) (figure 12.2). This transfers the write data from the
lower byte to TCNT or TCSR.
Summary of Contents for HD6417032
Page 21: ......
Page 35: ...xiv ...
Page 85: ...50 ...
Page 101: ...66 ...
Page 129: ...94 ...
Page 135: ...100 ...
Page 343: ...308 ...
Page 369: ...334 ...
Page 383: ...348 ...
Page 475: ...440 ...
Page 525: ...490 CK RAS CAS TRp TRc TRcc tRASD1 tRASD2 tCASD3 tCASD2 TRr tCSR Figure 20 18 Self Refresh ...
Page 578: ...543 CK RAS CAS TRp TRc TRcc tRASD1 tRASD2 tCASD3 tCASD2 TRr tCSR Figure 20 62 Self Refresh ...
Page 689: ...654 ...