MC68HC908LJ12 Datasheet, PDF (347/413 Pages) Freescale Semiconductor, Inc – 8-bit microcontroller units

Input/Output (I/O) Ports
T1CH[1:0] — Timer 1 Channel I/O Bits
The T1CH1 and T1CH0 pins are the TIM1 input capture/output
compare pins. The edge/level select bits, ELSxB:ELSxA, determine
whether the PTB2/T1CH0 and PTB3/T1CH1 pins are timer channel
I/O pins or general-purpose I/O pins. See Section 11. Timer
Interface Module (TIM).
T2CH[1:0] — Timer 2 Channel I/O Bits
The T2CH1 and T2CH0 pins are the TIM1 input capture/output
compare pins. The edge/level select bits, ELSxB:ELSxA, determine
whether the PTB4/T2CH0 and PTB5/T2CH1 pins are timer channel
I/O pins or general-purpose I/O pins. See Section 11. Timer
Interface Module (TIM).
ADC[5:4] — ADC channels 5 and 4
ADC[5:4] are pins used for the input channels to the analog-to-digital
converter module. The channel select bits, ADCH[4:0], in the ADC
status and control register define which port pin will be used as an
ADC input and overrides any control from the port I/O logic. See
Section 15. Analog-to-Digital Converter (ADC).
NOTE:
Care must be taken when reading port B while applying analog voltages
to ADC[5:4] pins. If the appropriate ADC channel is not enabled,
excessive current drain may occur if analog voltages are applied to the
PTBx/ADCx pin, while PTB is read as a digital input. Those ports not
selected as analog input channels are considered digital I/O ports.
LED drive — Direct LED Drive Pins
PTB0–PTB5 pins can be configured for direct LED drive. See 17.4.3
Port B LED Control Register (LEDB).
17.4.2 Data Direction Register B (DDRB)
Data direction register B determines whether each port B pin is an input
or an output. Writing a logic 1 to a DDRB bit enables the output buffer for
the corresponding port B pin; a logic 0 disables the output buffer.
Technical Data
348
Input/Output (I/O) Ports
MC68HC908LJ12 — Rev. 2.1
Freescale Semiconductor