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MC68341 USER’S MANUAL
MOTOROLA
4.3.5.7 PORT B DATA REGISTER (PORTB, PORTB1). This is a single register that can
be accessed at two different addresses. This register affects only those pins configured as
discrete I/O. A write is stored in the internal data latch, and if any port B pin is configured
as an output, the value stored for that bit is driven on the pin. A read of this register
returns the value stored in the register only if the pin is configured as a discrete output.
Otherwise, the value read is the value of the pin. This register can be read or written at
any time.
PORTB, PORTB1
$019, 01B
76543210
P7
P6
P5
P4
P3
P2
P1
P0
RESET:
UUUUUUUU
Supervisor/User
4.3.5.8 PORT C PIN ASSIGNMENT REGISTER (PPARC). The MC68341 has multiplexed
functions on several pins that had a dedicated function on the MC68340. Five new signals
have been added to the DMA module, and the RTCOUT signal is multiplexed with RMC .
These new alternate functions are selected by setting the appropriate bit in PPARC.
PPARC
$029
76543210
TIN
RDY2
TGATE
RDY1
DACK2
DDACK2
DACK1
DDACK1
FC3
DTC
RMC
RTCOUT
0
RESET:
00000000
Supervisor Only
4.4 REAL TIME CLOCK
The SIM41 includes a real time clock and calendar function (RTC), that counts seconds,
minutes, hours, days, day of the week, date of the month, month, and year with leap year
compensation. The RTC can generate both an internal interrupt and an external output
(RTCOUT) based on an alarm or time matching function.
The 32.768kHz oscillator and the RTC can continue to operate from the VBATT power pin
when VCC is turned off. In typical applications V BATT is connected to a 3V lithium battery
to provide backup of the RTC time function. If the RMC /RTCOUT signal is configured as
RTCOUT before VCC is powered down, the output drivers for RTCOUT are also powered
from VBATT to allow the alarm output to be seen by other system devices. During initial
system debug, or for systems which do not require the time function to be non-volatile,
VBATT and BSW can be connected to VCC to eliminate the need for a separate power
supply source.
4.4.1 Reset
Hardware RESET does not affect the clock or calendar functions of the RTC. When
RESET is asserted, the following occurs:
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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