Input/Output Ports
Port C
MC68HC(7)05H12
—
Rev. 1.0
General Release Specification
MOTOROLA
Input/Output Ports
83
L
G
R
7.5 Port C
Port C is an 8-bit bidirectional port. The port C data register is at $0002,
the port C data direction register (DDR) is at $0006 and the port C control
register is at $0007. Reset does not affect the data registers, but clears
the data direction registers, thereby returning the ports to inputs. Writing
a one to a DDR bit sets the corresponding port bit to output mode. Reset
clears the control register. The port pins PC0–PC5 are shared with the
16-bit timers (TCAP0–3, TCMP0–1). The lines PC0–PC3 must be set to
input by resetting the DDR to enable correct input capture function. If the
TCMP1 or TCMP2 bit in the control register is set the pins PC5, PC4
function as output compare lines from the Timer1 system otherwise they
function as I/O lines. The port pins PC6, PC7 are shared with the SCI
system (RDI, TDO). If the SCI is enabled the pins PC6, PC7 are
connected to the SCI system.
7.6 Port D
Port D is an 4-bit input only port which shares all of its pins with the A/D
converter (AN0 through AN3). The port D data register is located at
address $0003. When the A/D converter is active, one of these 4 input
lines may be selected by the A/D multiplexer for conversion. A logical
read of a selected input port will always return 0.
7.7 Port E and Port F (Power Drivers)
Port E is an 8-bit output only port. The port E data register is at $0040.
Reset clears the data register. The eight lines are shared with four PWM
H-bridge driver pairs (left and right). The outputs are formed by power
drivers. The port E PWM lines can support two 360
°
(large angle) aircore
instruments.
Port F is a 4-bit output only port. The port F data register is at $0042.
Reset clears the data register. The four lines are shared with four PWM
channels. The outputs are formed by power drivers. The port F PWM
lines can support four 90
°
(small angle) aircore instruments.