Application Information; External Pins And Routing - ROHS MC9S08QE128 Reference Manual

10.6

Application Information

This section contains information for using the ADC module in applications. The ADC has been designed
to be integrated into a microcontroller for use in embedded control applications requiring an A/D
converter.
10.6.1

External Pins and Routing

The following sections discuss the external pins associated with the ADC module and how they should be
used for best results.
10.6.1.1 Analog Supply Pins
The ADC module has analog power and ground supplies (V
separate pins on some devices. On other devices, V
and on others, both V
SSAD
are separate pads for the analog supplies which are bonded to the same pin as the corresponding digital
supply so that some degree of isolation between the supplies is maintained.
When available on a separate pin, both V
as their corresponding MCU digital supply (V
noise immunity and bypass capacitors placed as near as possible to the package.
Freescale Semiconductor
RESET
INITIALIZE ADC
ADCCFG = $98
ADCSC2 = $00
ADCSC1 = $41
CHECK
COCO=1?
READ ADCRH
THEN ADCRL TO
CLEAR COCO BIT
CONTINUE
Figure 10-14. Initialization Flowchart for Example
and V are shared with the MCU digital supply pins. In these cases, there
DDAD
and V
DDAD
DD
MC9S08QE128 MCU Series Reference Manual, Rev. 2
12-bit Analog-to-Digital Converter (S08ADCV1)
NO
YES
and V
DDAD
is shared on the same pin as the MCU digital V
SSAD
must be connected to the same voltage potential
SSAD
and V ) and must be routed carefully for maximum
SS
) which are available as
SSAD
,
SS
197