MC68HC908GR8A_07 Datasheet, PDF (49/260 Pages) Freescale Semiconductor, Inc – Microcontrollers

INTERNAL DATA BUS
READ DDRBx
WRITE DDRBx
RESET
WRITE PTBx
READ PTBx
DDRBx
PTBx
Functional Description
DISABLE
PTBx
ADC CHANNEL x
INTERRUPT
LOGIC
CONVERSION
COMPLETE
AIEN COCO
CGMXCLK
BUS CLOCK
DISABLE
ADC DATA REGISTER
ADC
ADC
VOLTAGE IN
(V_ADIN)
V_REFH
V_REFL
CHANNEL
SELECT
ADCH4–ADCH0
ADC CLOCK
CLOCK
GENERATOR
ADIV2–ADIV0
ADICLK
Figure 3-2. ADC Block Diagram
3.3.2 Voltage Conversion
When the input voltage to the ADC equals V_REFH, the ADC converts the signal to $FF (full scale). If the
input voltage equals V_REFL, the ADC converts it to $00. Input voltages between V_REFH and V_REFL are a
straight-line linear conversion.
NOTE
The ADC input voltage must always be greater than V_SSA and less than
V_DDA. V_REFH must always be greater than or equal to V_REFL.
NOTE
Connect the V_DDA pin to the same voltage potential as the V_DD pin, and
connect the V_SSA pin to the same voltage potential as the V_SS pin. The
V_DDA pin should be routed carefully for maximum noise immunity.
MC68HC908GR8A • MC68HC908GR4A Data Sheet, Rev. 5
Freescale Semiconductor
49