MC9S12C Datasheet, PDF (106/680 Pages) Motorola, Inc – 16-Bit Microcontroller

Chapter 2 Port Integration Module (PIM9C32) Block Description
2.4.2.5 Port P
The PWM module is connected to port P. Port P pins can be used as PWM outputs. Further the Keypad
Wake-Up function is implemented on pins PP[7:0]. During reset, port P pins are configured as high-
impedance inputs.
Port P offers 8 general purpose I/O pins with edge triggered interrupt capability in wired-or fashion. The
interrupt enable as well as the sensitivity to rising or falling edges can be individually configured on per
pin basis. All 8 bits/pins share the same interrupt vector. Interrupts can be used with the pins configured
as inputs or outputs.
An interrupt is generated when a bit in the port interrupt flag register and its corresponding port interrupt
enable bit are both set. This external interrupt feature is capable to wake up the CPU when it is in STOP
or WAIT mode.
A digital filter on each pin prevents pulses (Figure 2-48) shorter than a specified time from generating an
interrupt. The minimum time varies over process conditions, temperature and voltage (Figure 2-47 and
Table 2-38).
Glitch, filtered out, no interrupt flag set
Valid pulse, interrupt flag set
t_pign
t_pval
Figure 2-47. Interrupt Glitch Filter on Port P and J (PPS = 0)
Table 2-38. Pulse Detection Criteria
Pulse
STOP Mode
Value
Unit
STOP⁽¹⁾ Mode
Value
Unit
Ignored
t_pign <= 3
Bus clocks
t_pign <= 3.2
µs
Uncertain
3 < t_pulse < 4 Bus clocks 3.2 < t_pulse < 10
µs
Valid
t_pval >= 4
Bus clocks
t_pval >= 10
µs
1. These values include the spread of the oscillator frequency over temperature,
voltage and process.
t_pulse
Figure 2-48. Pulse Illustration
106
MC9S12C-Family / MC9S12GC-Family
Freescale Semiconductor
Rev 01.23