MC9S08QG8_09 Datasheet, PDF (28/314 Pages) Freescale Semiconductor, Inc – HCS08 Microcontrollers

Chapter 2 External Signal Description
SYSTEM
POWER
+
3V
V_DD
C_{BLK +}
10 μF
MC9S08QG8/4
V_DD
C_BY
0.1 μF
V_SS
PORT
A
NOTE 1
R_F
R_S
C1
X1
C2
XTAL
NOTE 2
EXTAL
NOTE 2
BACKGROUND HEADER
V_DD
ASYNCHRONOUS
INTERRUPT
INPUT
V_DD
4.7 kΩ–10 kΩ
OPTIONAL
MANUAL
RESET
0.1 μF
BKGD
RESET/IRQ
PORT
B
PTA0/KBIP0/TPMCH0/ADP0/ACMP+
PTA1/KBIP1/ADP1/ACMP–
PTA2/KBIP2/SDA/ADP2
PTA3/KBIP3/SCL/ADP3
PTA4/ACMPO/BKGD/MS
PTA5/IRQ/TCLK/RESET
I/O AND
PERIPHERAL
INTERFACE TO
APPLICATION
SYSTEM
PTB0/KBIP4/RxD/ADP4
PTB1/KBIP5/TxD/ADP5
PTB2/KBIP6/SPSCK/ADP6
PTB3/KBIP7/MOSI/ADP7
PTB4/MISO
PTB5/TPMCH1/SS
PTB6/SDA/XTAL
PTB7/SCL/EXTAL
NOTES:
1. Not required if using the internal clock option.
2. XTAL is the same pin as PTB6; EXTAL the same pin as PTB7.
3. The RESET pin can only be used to reset into user mode; you can not enter BDM using the RESET pin.
BDM can be entered by holding MS low during POR or writing a 1 to BDFR in SBDFR with MS low after
issuing the BDM command.
4. IRQ feature has optional internal pullup device.
5. RC filter on RESET/IRQ pin recommended for noisy environments.
Figure 2-4. Basic System Connections
2.2.1 Power
V_DD and V_SS are the primary power supply pins for the MCU. This voltage source supplies power to all
I/O buffer circuitry, ACMP and ADC modules, and to an internal voltage regulator. The internal voltage
regulator provides a regulated lower-voltage source to the CPU and other internal circuitry of the MCU.
Typically, application systems have two separate capacitors across the power pins: a bulk electrolytic
capacitor, such as a 10-μF tantalum capacitor, to provide bulk charge storage for the overall system, and a
bypass capacitor, such as a 0.1-μF ceramic capacitor, located as near to the MCU power pins as practical
to suppress high-frequency noise.
MC9S08QG8 and MC9S08QG4 Data Sheet, Rev. 5
26
Freescale Semiconductor