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M0A21/M0A23 Series
May 06, 2022
Page
683
of 746
Rev 1.02
M0
A21
/M
0
A
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SE
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TEC
H
NICAL
RE
FEREN
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ANUAL
6.19 Analog-to-Digital Converter (ADC)
6.19.1 Overview
The chip contains one 12-bit successive approximation analog-to-digital converter (SAR A/D converter)
with twenty one input channels. The A/D converter supports four operation modes: Single, Burst, Single-
cycle Scan and Continuous Scan mode.
The A/D converter can be started by software, external pin,
timer0~3 overflow pulse trigger and PWM trigger.
6.19.2 Features
Analog input voltage range: 0 ~ AV
DD
(voltage of V
DD
pin).
12-bit resolution and 10-bit accuracy is guaranteed
Up to 17 single-end analog input channels or 8 differential analog input channels
Maximum ADC peripheral clock frequency is 16 MHz
Up to 800k SPS sampling rate
Configurable ADC internal sampling time
Four operation modes:
–
Single mode: A/D conversion is performed one time on a specified channel.
–
Burst mode: A/D converter samples and converts the specified single channel and
sequentially stores the result in FIFO.
–
Single-cycle Scan mode: A/D conversion is performed only one cycle on all specified
channels with the sequence from the smallest numbered channel to the largest
numbered channel.
–
Continuous Scan mode: A/D converter continuously performs Single-cycle Scan mode
until software stops A/D conversion.
An A/D conversion can be started by:
–
Software Write 1 to ADST bit
–
External pin (STADC)
–
Timer 0~3 overflow pulse trigger
–
PWM trigger with optional start delay period
Each conversion result is held in data register of each channel with valid and overrun
indicators.
Conversion result can be compared with specified value and user can select whether to
generate an interrupt when conversion result matches the compare register setting.
4 internal channels, they are band-gap voltage (V
BG
), temperature sensor (V
TEMP
), internal
reference voltage and DAC0 output
Support PDMA transfer mode.
Note 1
: ADC sampling rate = (ADC peripheral clock frequency) / (total ADC conversion cycle)
Note 2
: If the internal channel (V
TEMP
) is selected to convert, the sampling rate needs to be less
than 25k SPS for accurate result.
Note 3
: If the internal channel for band-gap voltage is active, the maximum sampling rate will be
25k SPS.