SN32F280 Series
32-Bit Cortex-M0 Micro-Controller
SONiX TECHNOLOGY CO., LTD
Page 95
Version 1.1
GPIO mode must be set as input mode and inactive (no pull-down/up resistor enabled, Schmitt trigger disabled) with
GPIO2_MODE
and
GPIO2_CFG
register by program.
Only one pin of Port 2 can be configured as ADC input in the same time. The pins of Port 2 configured as ADC input
channel must be set as input mode, inactive (no pull-down/pull-up resistor enabled, Schmitt trigger disabled, Data
register keep low) with
GPIO2_MODE
and
GPIO2_CFG
register by program to avoid current leakage.
Note: The GPIO mode of ADC input channels used must be set as input mode and inactive (no
pull-down/pull-up resistor enabled, Schmitt trigger disabled, Data register keep low) with
GPIO2_MODE and GPIO2_CFG register by program.
7.4 ADC CIRCUIT
VCC
GND
0.1uF
Analog Signal Input
47uF
0.1uF
External High
Reference Voltage
Main Power Trunk
AINn/P2.n
VSS
AVREFH
MCU
A
B
C
The analog signal is inputted to ADC input pin “AINn/P2.n”. The ADC input signal must be through a 0.1uF capacitor “A”.
The 0.1uF capacitor is set between ADC input pin and VSS pin, and must be on the side of the ADC input pin as
possible. Don’t connect the capacitor’s ground pin to ground plain directly, and must be through VSS pin. The capacitor
can reduce the power noise effective coupled with the analog signal.
If the ADC high reference voltage is from external voltage source, the external high reference is connected to AVREFH
pin (P2.0). The external high reference source must be through a 47uF ”C” capacitor first, and then 0.1uF capacitor “B”.
These capacitors are set between AVREFH pin and VSS pin, and must be on the side of the AVREFH pin as possible.
Don’t connect the capacitor’s ground pin to ground plain directly, and must be through VSS pin.
Содержание SN32F280 Series
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