MC68HC908EY16 Datasheet, PDF (23/278 Pages) Motorola, Inc – Microcontrollers

Pin Functions
MCU
V_DD
V_SS
C1
0.1 µF
+
C2
V_DD
Note: Component values shown represent typical applications.
Figure 1-3. Power Supply Bypassing
1.5.2 Oscillator Pins (PTC4/OSC1 and PTC3/OSC2)
The OSC1 and OSC2 pins are available through programming options in the configuration register. These
pins then become the connections to an external clock source or crystal/ceramic resonator.
When selecting PTC4 and PTC3 as I/O, OSC1 and OSC2 functions are not available.
1.5.3 External Reset Pin (RST)
A logic 0 on the RST pin forces the MCU to a known startup state. RST is bidirectional, allowing a reset
of the entire system. It is driven low when any internal reset source is asserted. This pin contains an
internal pullup resistor that is always activated, even when the reset pin is pulled low. See Chapter 14
System Integration Module (SIM).
1.5.4 External Interrupt Pin (IRQ)
IRQ is an asynchronous external interrupt pin. This pin contains an internal pullup resistor that is always
activated, even when the IRQ pin is pulled low. See Chapter 9 External Interrupt (IRQ).
1.5.5 Analog Power Supply/Reference Pins (V_DDA, V_REFH, V_SSA and V_REFL)
V_DDA and V_SSA are the power supply pins for the analog-to-digital converter (ADC). Decoupling of these
pins should be as per the digital supply.
NOTE
V_REFH is the high reference supply for the ADC. V_DDA should be tied to the
same potential as V_DD via separate traces.
V_REFL is the low reference supply for the ADC. V_SSA should be tied to the
same potential as V_SS via separate traces.
See Chapter 3 Analog-to-Digital Converter (ADC) Module.
MC68HC908EY16 • MC68HC908EY8 Data Sheet, Rev. 10
Freescale Semiconductor
23