ez80f91 ZiLOG Semiconductor, ez80f91 Datasheet - Page 169

• Manufacturer Part Number: ez80f91
• Description: Ez80 Acclaimplus!? Connectivity Assp Ez80f91 Assp
• Manufacturer: ZiLOG Semiconductor

Table 80. Real-Time Clock Seconds Register
PS027001-0707
Bit
Reset
CPU Access
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
Binary Operation (BCD_EN = 0)
Bit Position
[7:0]
SEC
Real-Time Clock Registers
•
•
•
The RTC registers are accessed via the address and data buses using I/O instructions. The
RTC_UNLOCK control bit 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
Value Description
0–5
0–9
Value
00h–3Bh The current seconds count.
Write values to the RTC count registers to set the current time
Write values to the RTC alarm registers to set the appropriate alarm conditions
Write to RTC_CTRL to clear RTC_UNLOCK; clearing the RTC_UNLOCK bit resets
and enables the clock divider
R/W*
The tens digit of the current seconds count.
The ones digit of the current seconds count.
X
7
Description
Table
R/W*
X
6
80.
R/W*
X
5
R/W*
X
4
(RTC_SEC = 00E0h)
R/W*
X
3
R/W*
X
2
R/W*
X
1
Product Specification
R/W*
X
0
eZ80F91 ASSP
Real-Time Clock
161