mc68hc908lj24 Freescale Semiconductor, Inc, mc68hc908lj24 Datasheet - Page 228

• Manufacturer Part Number: mc68hc908lj24
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Real Time Clock (RTC)
Data Sheet
228
Note: Reading RTCWE[1:0]
Write any value
other than 10
to RTWE
always return 00.
Write-Protect
DISABLED
Figure 12-5. RTC Write Protect State Diagram
The mechanism uses the RTCWE[1:0] bits in the RTC calibration control
register (RTCCOMR) in a state machine, which requires a bit-write
sequence to disable the write-protection. A block diagram of the state
machine is shown in
After a reset, the write-protect mechanism is disabled, allowing the user
code to calibrate the RTC clock, set the time in the clock registers, and
set the date in the calendar registers.
To enable write-protect after reset or write-protect is disabled execute
the following code:
RTCWE1 EQU
RTCWE0 EQU
Write any value
other than 00
to RTWE
Real Time Clock (RTC)
RTCWE = 00
1
0
Figure
;RTCWE1 bit
;RTCWE0 bit
12-5.
Write-Protect ENABLED
RTCWE 01
MC68HC908LJ24/LK24 — Rev. 2.1
Freescale Semiconductor
RTCWE = 10
RTCWE = 11