EZ80L92MCU Datasheet, PDF (105/241 Pages) Zilog, Inc. – eZ80Acclaim Flash Microcontrollers

eZ80L92 MCU
Product Specification
90
Real-Time Clock Registers
The real-time clock registers are accessed via the address and data bus using I/O instruc-
tions. RTC_UNLOCK controls access to the RTC count registers. When unlocked
(RTC_UNLOCK = 1), the RTC count is disabled and the count registers are Read/Write.
When locked (RTC_UNLOCK = 0), the RTC count is enabled and the count registers are
Read-Only. The default, at RESET, is for the RTC to be locked.
Real-Time Clock Seconds Register
This register contains the current seconds count. The value in the RTC_SEC register is
unchanged by a RESET. The current setting of BCD_EN determines whether the values in
this register are binary (BCD_EN = 0) or binary-coded decimal (BCD_EN = 1). Access to
this register is Read-Only if the RTC is locked and Read/Write if the RTC is unlocked. See
Table 38.
Table 38. Real-Time Clock Seconds Register (RTC_SEC = 00E0h)
Bit
7
6
5
4
3
2
1
0
Reset
X
X
X
X
X
X
X
X
CPU Access
R/W* R/W* R/W* R/W* R/W* R/W* R/W* R/W*
Note: X = Unchanged by RESET; R/W* = Read-only if RTC locked, Read/Write if RTC unlocked.
Binary-Coded-Decimal Operation (BCD_EN = 1)
Bit
Position
[7:4]
TEN_SEC
[3:0]
SEC
Value Description
0–5 The tens digit of the current seconds count.
0–9 The ones digit of the current seconds count.
Binary Operation (BCD_EN = 0)
Bit
Position
[7:0]
SEC
Value Description
00h– The current seconds count.
3Bh
PS013012-1004
PRELIMINARY
Real-Time Clock