C8051F336_08 Datasheet, PDF (48/227 Pages) Silicon Laboratories – Mixed-Signal Byte-Programmable EPROM MCU

C8051F336/7/8/9
7.4. ADC0 Analog Multiplexer (C8051F336/8 only)
ADC0 on the C8051F336/8 has two analog multiplexers, referred to collectively as AMUX0.
AMUX0 selects the positive and negative inputs to the ADC. Any of the following may be selected as the
positive input: Port I/O pins, the on-chip temperature sensor, or the positive power supply (V_DD). Any of the
following may be selected as the negative input: Port I/O pins, V_REF, or GND. When GND is selected as
the negative input, ADC0 operates in Single-ended Mode; all other times, ADC0 operates in Differ-
ential Mode. The ADC0 input channels are selected in the AMX0P and AMX0N registers as described in
SFR Definition 7.9 and SFR Definition 7.10.
P0.0
AMX0P
Temp
Sensor
P2.3*
VDD
P0.0
AMUX
AIN+
ADC0
AIN-
AMUX
AMX0N
P2.3*
VREF
GND
*P2.0-P2.3 Only available as
inputs on QFN24 Packaging
Figure 7.8. ADC0 Multiplexer Block Diagram
Important Note About ADC0 Input Configuration: Port pins selected as ADC0 inputs should be config-
ured as analog inputs, and should be skipped by the Digital Crossbar. To configure a Port pin for analog
input, set to ‘0’ the corresponding bit in register PnMDIN. To force the Crossbar to skip a Port pin, set to ‘1’
the corresponding bit in register PnSKIP. See Section “20. Port Input/Output” on page 119 for more Port
I/O configuration details.
48
Rev.1.0