68HC(9)12DG128 Rev 1.0
36
Pinout and Signal Descriptions
MOTOROLA
of the DBE is controlled by the NDBE bit in the PEAR register. DBE is
enabled out of reset in expanded modes. This pin has an active pull-up
during and after reset in single chip modes.
Inverted E clock
(ECLK)
The ECLK pin (PE7) can be used to latch the address for
de-multiplexing. It has the same behavior as the ECLK, except is
inverted. In expanded modes this pin is used to enable the drive control
of external buses during external reads. Use of the ECLK is controlled
by the NDBE and DBENE bits in the PEAR register.
Calibration
reference (CAL)
The CAL pin (PE7) is the output of the Slow Mode programmable clock
divider, SLWCLK, and is used as a calibration reference. The SLWCLK
frequency is equal to the crystal frequency out of reset and always has
a 50% duty. If the DBE function is enabled it will override the enabled
CAL output. The CAL pin output is disabled by clearing CALE bit in the
PEAR register.
Clock generation
module test
(CGMTST)
The CGMTST pin (PE6) is the output of the clocks tested when CGMTE
bit is set in PEAR register. The PIPOE bit must be cleared for the clocks
to be tested.
Table 7 XC68HC912D60 Signal Description Summary
Pin Name
Shared
port
Pin
Number
112-pin
47
48
Description
EXTAL
XTAL
-
-
Crystal driver and external clock input pins. On reset all the device clocks
are derived from the EXTAL input frequency. XTAL is the crystal output.
RESET
-
46
An active low bidirectional control signal, RESET acts as an input to
initialize the MCU to a known start-up state, and an output when COP or
clock monitor causes a reset.
ADDR[7:0]
DATA[7:0]
ADDR[15:8]
DATA[15:8]
PB[7:0]
31–24
External bus pins share function with general-purpose I/O ports A and B.
In single chip modes, the pins can be used for I/O. In expanded modes, the
pins are used for the external buses.
PA[7:0]
64–57
DBE
PE7
36
Data bus control and, in expanded mode, enables the drive control of
external buses during external reads.
12-pins