Datasheet

Chapter 2 Pins and Connections
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 27
2.2 Recommended System Connections
Figure 2-4 shows pin connections that are common to MC9S08SG8 application systems.
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 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. In this case, there
should be a bulk electrolytic capacitor, such as a 10-F tantalum capacitor, to provide bulk charge storage
BKGD/MS
RESET
OPTIONAL
MANUAL
RESET
V
DD
BACKGROUND HEADER
SYSTEM
POWER
PORT
B
PTB0/PIB0/RxD/ADP4
PTB1/PIB1/TxD/ADP5
PTB2/PIB2/SPSCK/ADP6
PTB3/PIB3/MOSI/ADP7
PTB4/TPM2CH1/MISO
PTB5/TPM1CH1/SS
PTB6/SDA/XTAL
PTB7/SCL/EXTAL
PORT
C
PTC0/TPM1CH0/ADP8
PTC1/TPM1CH1/ADP9
PTC2/ADP10
PTC3/ADP11
MC9S08SG8
V
SS
V
DD
C
BY
0.1 F
C
BLK
10 F
+
5 V
+
C2
C1
X1
R
F
R
S
PORT
A
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
PTA1/PIA1/TPM2CH0/ADP1/ACMP-
PTA2/PIA2/SDA/ADP2/ACMPO
PTA3/PIA3/SCL/ADP3
0.1 F
V
DD
4.7 k  –10 k 
NOTE 1
NOTES:
1. External crystal circuit not required if using the internal clock option.
2. RESET
pin can only be used to reset into user mode, you can not enter BDM using 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 BDM command.
3. RC filter on RESET
pin recommended for noisy environments.