Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Data Sheet
Product codes
ATSAMD21-XPRO
857
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181C–SAM-D21_Datasheet–07/2014
z
Bits 23:20 – INPUTOFFSET[3:0]: Positive Mux Setting Offset
The pin scan is enabled when INPUTSCAN != 0. Writing these bits to a value other than zero causes the first con-
version triggered to be converted using a positive input equalto MUXPOS + INPUTOFFSET. Setting this register
to zero causes the first conversion to use a positive input equal to MUXPOS.
After a conversion, the INPUTOFFSET register will be incremented by one, causing the next conversion to be
done with the positive input equal to MUXPOS + INPUTOFFSET. The sum of MUXPOS and INPUTOFFSET gives
the input that is actually converted.
The pin scan is enabled when INPUTSCAN != 0. Writing these bits to a value other than zero causes the first con-
version triggered to be converted using a positive input equalto MUXPOS + INPUTOFFSET. Setting this register
to zero causes the first conversion to use a positive input equal to MUXPOS.
After a conversion, the INPUTOFFSET register will be incremented by one, causing the next conversion to be
done with the positive input equal to MUXPOS + INPUTOFFSET. The sum of MUXPOS and INPUTOFFSET gives
the input that is actually converted.
z
Bits 19:16 – INPUTSCAN[3:0]: Number of Input Channels Included in Scan
This register gives the number of input sources included in the pin scan. The number of input sources included is
INPUTSCAN + 1. The input channels included are in the range from MUXPOS + INPUTOFFSET to MUXPOS +
INPUTOFFSET + INPUTSCAN.
The range of the scan mode must not exceed the number of input channels available on the device.
This register gives the number of input sources included in the pin scan. The number of input sources included is
INPUTSCAN + 1. The input channels included are in the range from MUXPOS + INPUTOFFSET to MUXPOS +
INPUTOFFSET + INPUTSCAN.
The range of the scan mode must not exceed the number of input channels available on the device.
z
Bits 15:13 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to
zero when this register is written. These bits will always return zero when read.
z
Bits 12:8 – MUXNEG[4:0]: Negative Mux Input Selection
These bits define the Mux selection for the negative ADC input.
These bits define the Mux selection for the negative ADC input.
shows the possible input selections.
0x4
16X
16x
0x5-0xE
Reserved
0xF
DIV2
1/2x
Table 32-13. Negative Mux Input Selection
Value
Name
Description
0x00
PIN0
ADC AIN0 pin
0x01
PIN1
ADC AIN1 pin
0x02
PIN2
ADC AIN2 pin
0x03
PIN3
ADC AIN3 pin
0x04
PIN4
ADC AIN4 pin
0x05
PIN5
ADC AIN5 pin
0x06
PIN6
ADC AIN6 pin
0x07
PIN7
ADC AIN7 pin
0x08-0x17
–
Reserved
0x18
GND
Internal ground
0x19
IOGND
I/O ground
0x1A-0x1F
–
Reserved
GAIN[3:0]
Name
Description