MC9S08GT16ACBE Datasheet, PDF (30/300 Pages) Freescale Semiconductor, Inc – Microcontrollers

Pins and Connections
2.3.5 IRQ — External Interrupt Request Pin
IRQ is a dedicated pin with both pullup and pulldown devices built in. This pin has no output capabilities.
After a system reset, the IRQ pin is disabled and must be enabled before use. See Section 5.4.2, “IRQ —
External Interrupt Request Pin” for more details.
For EMC-sensitive applications, an external RC filter is recommended on the IRQ pin. See Figure 2-5 for
an example.
2.3.6 General-Purpose I/O and Peripheral Ports
The remaining 36 pins are shared among general-purpose I/O and on-chip peripheral functions such as
timers and serial I/O systems. (Three of these pins are not bonded out on the 44-pin package, five are not
bonded out on the 42-pin package, and 15 are not bonded out on the 32-pin package.) Immediately after
reset, all 36 of these pins are configured as high-impedance general-purpose inputs with internal pullup
devices disabled.
NOTE
To avoid extra current drain from floating input pins, the reset initialization
routine in the application program should either enable on-chip pullup
devices or change the direction of unused pins to outputs so the pins do not
float.
For information about controlling these pins as general-purpose I/O pins, see Chapter 6, “Parallel
Input/Output.” For information about how and when on-chip peripheral systems use these pins, refer to the
appropriate section from Table 2-1.
Table 2-1. Pin Sharing References
Port Pins
Alternate Function
Reference¹
PTA7–PTA0
KBIP7–KBIP0
Chapter 7, “Keyboard Interrupt (S08KBIV1)”
PTB7–PTB0 ADP7–ADP0
Chapter 14, “Analog-to-Digital Converter (S08ATDV3)”
PTC7–PTC4
PTC3–PTC2 SCL–SDA
Chapter 13, “Inter-Integrated Circuit (S08IICV1)”
PTC1–PTC0 RxD2–TxD2
Chapter 11, “Serial Communications Interface (S08SCIV1)”
PTD4–PTD3 TPM2CH1–TPM2CH0, TPM2CLK Chapter 10, “Timer/PWM (S08TPMV2)”
PTD2–PTD0 TPM1CH2–TPM1CH0, TPM1CLK Chapter 10, “Timer/PWM (S08TPMV2)”
PTE5
PTE4
PTE3
PTE2
SPSCK
MISO
MOSI
SS
Chapter 12, “Serial Peripheral Interface (S08SPIV3)”
PTE1–PTE0 RxD1–TxD1
Chapter 11, “Serial Communications Interface (S08SCIV1)”
PTG3
PTG2–PTG1 EXTAL–XTAL
Chapter 9, “Internal Clock Generator (S08ICGV4)”
PTG0
BKGD/MS
Chapter 15, “Development Support”
1 _{See this section for information about modules that share these pins.}
MC9S08GT16A/GT8A Data Sheet, Rev. 1
30
Freescale Semiconductor