MC68HC08BD24 Datasheet, PDF (199/244 Pages) Motorola, Inc – HCMOS Microcontroller Unit

15.5 Port C
Port C is an 6-bit special-function port that shares all six of its pins with
the analog-to-digital converter (ADC) module.
15.5.1 Port C Data Register
The port C data register (PTC) contains a data latch for each of the
seven port C pins.
Address: $0002
Bit 7
6
5
4
3
2
1
Bit 0
Read: 0
Write:
0
PTC5 PTC4 PTC3 PTC2 PTC1 PTC0
Reset:
Unaffected by reset
Alternate
Function:
ADC5 ADC4 ADC3 ADC2 ADC1 ADC0
= Unimplemented
Figure 15-9. Port C Data Register (PTC)
PTC5–PTC0 — Port C Data Bits
These read/write bits are software-programmable. Data direction of
each port C pin is under the control of the corresponding bit in data
direction register C. Reset has no effect on port C data.
ADC5–ADC0 — Analog-to-Digital Input Bits
ADC5–ADC0 are pins used for the input channels to the analog-to-
digital converter module. The channel select bits in the ADC Status
and Control Register define which port C pin will be used as an ADC
input and overrides any control from the port I/O logic by forcing that
pin as the input to the analog circuitry.
NOTE:
Care must be taken when reading port C while applying analog voltages
to ADC5–ADC0 pins. If the appropriate ADC channel is not enabled,
excessive current drain may occur if analog voltages are applied to the
PTCx/ADCx pin, while PTC is read as a digital input. Those ports not
selected as analog input channels are considered digital I/O ports.
MC68HC08BD24 — Rev. 1.1
Freescale Semiconductor
Technical Data
199