View detail for Atmel AVR1324: XMEGA ADC Selection Guide

AVR1324: XMEGA ADC Selection Guide
Features
The Atmel® AVR® XMEGA® A family
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Pipelined architecture
Up to 2M samples per second
Up to 12-bit resolution
Signed and unsigned mode
Selectable gain
2MHz maximum ADC frequency
Minimum single result propagation delay of 2.5μs (8-bit resolution)
Minimum single result propagation delay of 3.5μs (12-bit resolution)
Up to 4 virtual channels
Result comparator
Automatic calibration
Internal connection to DAC output
Optional DMA transfer of conversion results
8-bit Atmel
Microcontrollers
Application Note
The Atmel AVR XMEGA B and D families
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Cyclic architecture
Up to 200.000 samples per second
Up to 12-bit resolution
Signed and unsigned mode
Selectable gain
1.4MHz maximum ADC frequency
Minimum single result propagation delay of 3.57μs (8-bit resolution)
Minimum single result propagation delay of 5.0μs (12-bit resolution)
Optional DMA transfer of conversion results (for device with a DMA)
1 Introduction
Atmel AVR XMEGA devices are grouped into several families offering comparable
features. For example, the analog-to-digital converters (ADCs) on all A-family
XMEGA devices are identical.
Depending on the selected family, AVR XMEGA devices offer two ADC types. Both
are flexible modules suitable for a wide range of applications, such as data
acquisition, embedded control, and general signal processing.
This application note describes these two ADC types and helps users to select the
most suitable ADC for their application.
Rev. 8378A-AVR-10/2011
2 AVR XMEGA ADC Summary
The main differences between the Atmel AVR XMEGA ADCs are described in Table
2-1. This table provides a summary of ADC features. For more details, please refer to
individual product datasheets and manuals.
Table 2-1. ADC features
AVR XMEGA A specific
AVR XMEGA B specific
AVR XMEGA A
AVR XMEGA B
AVR XMEGA D
ADCA
Yes
Yes
Yes
ADCB
Yes
Yes
_
Channel 0
Yes
Yes
Yes
Channel 1
Yes
_
_
Channel 2
Yes
_
_
Channel 3
Yes
_
_
Pipelined
Cyclic
Cyclic
2MHz
1.4MHz
1.4MHz
7
7
7
5
5
5
2Msps
200ksps
200ksps
ADC result to DMA
Yes
Yes
_
SWEEP mode
Yes
_
_
4
3
3
Temperature
Temperature
Temperature
VCC/10
VCC/10
VCC/10
Bandgap
Bandgap
Bandgap
DAC
-
-
x 0.5 Gain
_
Yes
_
Voltage reference = INTVCC/2
_
Yes
_
Architecture
Max ADC frequency
Single propagation ADC
cycles number (12 bits)
Single propagation ADC
cycles number (8 bits)
Max sample per second
(12 bits)
(channel sweep)
Number of Internal inputs
Internal inputs
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3 ADC Selection guide
The following list of questions is intended to help provide guidance in finding the
appropriate Atmel AVR XMEGA ADC.
Table 3-1. ADC selection guide
Explanation
AVR XMEGA
What is the number of
ADC channels needed?
All AVR XMEGA ADCs offer 16 ADC
channels.
A, B, D
Are one or two external
references required?
All AVR XMEGA ADCs offer two
external references, even if only one
ADC is available.
A, B, D
What is the
propagation delay
needed?
If propagation delay >200ksps:
AVR XMEGA A offers 2Msps ADC.
Are one or two ADCs
needed?
A
If propagation delay ≤200ksps:
AVR XMEGA B and D offer 200ksps
ADC.
B, D
If simultaneous conversions are
required on different channels, two
ADCs are needed.
AVR XMEGA A and B offer two ADCs
A, B
If conversions on different channels
are consecutive, only one ADC is
needed.
D
AVR XMEGA D offers one ADC.
Is the DAC output
needed as internal
input?
Only AVR XMEGA A features this link
between DAC and ADC.
A
Is rail-to-rail conversion
needed?
Rail-to-rail conversion requires
accurate measurements around the ±
voltage reference value.
AVR XMEGA B offers x0.5 gain to
optimize rail-to-rail conversion.
B
Is sweep mode
required?
Sweep mode allows selecting the
number of channels used to trigger
the event controller.
Only AVR XMEGA A offers sweep
mode.
A
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4 ADC Architecture Overview
The Atmel AVR XMEGA A family offers a high-performance ADC capable of
conversion rates of up to 2Msps with a resolution of 12 bits.
The Atmel AVR XMEGA B and D families offer a high-performance ADC capable of
conversion rates up to 200ksps with a resolution of 12 bits.
This section provides an overview of the functionality and basic configuration options
of the ADC.
4.1 Basic element
The basic element uses switched capacitor technology combined with an operational
amplifier. Switched capacitor technology was chosen to reduce the power
consumption (compared to a technology-based resistor).
Figure 4-1. Basic element description
The input voltage, VIN, is compared to the voltage reference divided by two, VREF/2.
If VIN is smaller than VREF/2, this voltage is kept for the next iteration.
The logic output is 0.
This is the value of the most-significant bit (MSB).
If VIN is greater than VREF/2, VREF/2 is subtracted from VIN.
The logic output is 1.
This is the value of the MSB.
The result is multiplied by two and becomes the input of another basic element to
continue the conversion.
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4.2 Pipelined structure
The Atmel AVR XMEGA A family uses a pipelined ADC with 12 identical basic
elements. The first element will provide the MSB of the conversion, and the last one
will provide the LSB. A series of basic elements allows creating a pipelined
conversion.
When an element has finished its part of the conversion, it can then be re-used at
CLK speed for another conversion channel.
The maximum number of channels corresponds to the number of basic elements
used. The AVR XMEGA A family offers four levels (four ”virtual channels”) in the
ADC, and offers four result registers.
Figure 4-2. Pipelined structure description
The even basic elements (0, 2 …) will be enabled during the high level of the ADC
clock, and the odd basic elements (1, 3 …) will be enabled during the low level of the
ADC clock. This speeds up (x2) the conversion time versus the ADC clock frequency.
For more details, the Atmel application note “AVR1300: Using the Atmel AVR
XMEGA ADC” gives a complete description of the AVR XMEGA A.
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4.3 Cyclic structure
The Atmel AVR XMEGA B and D families offer a cyclic ADC. Instead of using 12
distinct basic elements, a single basic element is used 12 times in series for the MSB
to the LSB.
Figure 4-3. Cyclic structure description
In the cyclic ADC, the basic element has been modified slightly. It is made of two sets
of switched capacitors associated to a unique operational amplifier. The first set will
be enabled on the high level of the ADC clock, and the second one will be enabled on
the low level of the ADC clock.
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4.4 Differences between cyclic and pipelined structures
4.4.1 Cyclic propagation delay
With the cyclic structure, the minimum propagation delay corresponds to a conversion
without gain (gain equal to 1).
Depending on the gain value, several extra ADC cycles are added to the propagation
delay.
A new conversion is started after the end of the first one.
The example shows a conversion with:
•
•
•
One conversion channel: CH0
Conversion without gain on CH0
Conversion mode: Single-ended
Figure 4-4. Cyclic propagation delay
4.4.2 Pipelined propagation delay
With the pipelined structure, four basic elements are used at the same time. This
number corresponds to the number of virtual channels (four virtual channels for the
Atmel AVR XMEGA A).
The result is that four basic elements are active during the same ADC cycle. After the
end of the first conversion, a new end-of-conversion appears at each ADC cycle.
The pipelined structure is useful if several channels are converting at the same time.
The example (Figure 4-5) shows a conversion with:
•
•
•
•
Four conversion channels: CH0, CH1, CH2, and CH3
Two conversion channels without gain:
CH0 and CH1
Two conversion channels with gain: CH2 and CH3
Conversion mode: Free-running
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Figure 4-5. Pipelined propagation delay (with 4 channels used: 0, 1, 2, 3)
1
2
3
4
6
5
7
8
9
10
CLKADC
t
START CH0
without gain
t
START CH1
without gain
t
START CH2
with gain
t
START CH3
with gain
t
2
GAINSTAGE SAMPLE
CONV COMPLETE
0
1
2
3
2
GAINSTAGE AMPLIFY
ADC SAMPLE
3
2
3
2
3
0
1
t
3
2
t
3
0
t
0
1
t
5 Software interface
5.1 Software description
The Atmel AVR XMEGA ADCs are developed with compatibility over a common
architecture. Registers and bits follow the same rules.
The Atmel AVR XMEGA A ADC has more features than the AVR XMEGA B and D
ADCs. Firmware developed for the Atmel AVR XMEGA B and D ADC can run on the
AVR XMEGA A without any limitations. Firmware developed for the AVR XMEGA A
ADC can run on the AVR XMEGA B and D provided it only uses the more limited
features available on the AVR XMEGA B and D ADCs.
The AVR XMEGA ADC driver is available in the Atmel AVR Software Framework
(ASF). This driver is common for all AVR XMEGA ADCs. There are two examples
included in this framework, and they support both GCC and IAR™ toolchains:
• Using the internal temperature sensor
• Offset and gain calibration of the ADC
The ADC driver manages reserved bits and reserved registers. Firmware developed
on the AVR XMEGA B and D targets don’t need to be modified to run on the AVR
XMEGA A target.
Flags are defined within ASF to authorize only available registers when compiling.
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5.2 Channel registers
All registers dedicated to a channel are listed in Table 5-1. If the ADC has four
channels (AVR XMEGA A), four channel registers are available with the
corresponding addresses:
•
Channel 0: CTRL = 0x20, MUXCTRL = 0x21…
•
Channel 1: CTRL = 0x28, MUXCTRL = 0x29…
•
Channel 2: CTRL = 0x30, MUXCTRL = 0x31…
•
Channel 3: CTRL = 0x38, MUXCTRL = 0x39…
Table 5-1. Channel registers
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
0x00
CTRL
START
_
_
0x01
MUXCTRL
_
_
0x02
INTCTRL
_
_
_
_
0x03
INTFLAG
_
_
_
_
0x04
RESL
RES[7:0]
0x05
RESH
RES[15:8]
Bit 1
GAIN[2:0]
Bit 0
INPUTMODE[1:0]
MUXPOS[3:0]
MUXNEG[1:0]
INTMODE[1:0]
_
_
INTLVL[1:0]
_
IF
Only for channel 0:
0x06
SCAN
INPUTOFFSET[3:0]
INPUTSCAN[3:0]
5.3 ADC common registers
This section describes the register differences, and helps the user to check software
compatibility between ADCs.
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Table 5-2. ADC registers
AVR XMEGA A specific
AVR XMEGA B specific
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
0x00
CTRLA
DMASEL1
DMASEL0
CH3START
CH2START
CH1START
CH0START
0x01
CTRLB
_
_
_
CONVMODE
FREERUN
0x02
REFCTRL
_
REFSEL2
REFSEL1
REFSEL0
0x03
EVCTRL
SWEEP1
SWEEP0
EVSEL2
0x04
PRESCALER
_
_
_
0x06
INTFLAGS
0x07
TEMP
TEMP[7:0]
0x0C
CALL
CAL[7:0]
0x0D
CALH
0x10
CH0RESL
CH0RES[7:0]
0x11
CH0RESH
CH0RES[15:8]
0x12
CH1RESL
CH1RES[7:0]
0x13
CH1RESH
CH1RES[15:8]
0x14
CH2RESL
CH2RES[7:0]
0x15
CH2RESH
CH2RES[15:8]
0x16
CH3RESL
CH3RES[7:0]
0x17
CH3RESH
CH3RES[15:8]
0x18
CMPL
CMPL[7:0]
0x19
CMPH
CMPH[15:8]
0x20
CH0 Offset
Address of the first register dedicated to channel 0 is: 0x20
0x28
CH1 Offset
Address of the first register dedicated to channel 0 is: 0x28
0x30
CH2 Offset
Address of the first register dedicated to channel 0 is: 0x30
0x38
CH3 Offset
Address of the first register dedicated to channel 0 is: 0x38
_
_
_
Bit 2
Bit 1
Bit 0
FLUSH
ENABLE
RESOLUTION1
RESOLUTION0
_
_
_
BANDGAP
TEMPREF
EVSEL1
EVSEL0
EVACT2
EVACT1
EVACT0
_
_
PRESCALER2
PRESCALER1
PRESCALER0
CH3IF
CH2IF
CH1IF
CH0IF
_
CAL[11:8]
If the device has two ADC modules (Atmel AVR XMEGA A and B), all registers in
Table 2 1 are duplicated.
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6 Conversion mode selection
6.1 Introduction
The Atmel AVR XMEGA A, B, and D ADCs offer four modes:
• Internal: Input sources are connected to internal analog signals (temperature,
bandgap, etc.)
• Single-ended: The negative input is connected to ground. The input source is
connected to positive input
• Differential without gain: The input signal is connected between positive and
negative inputs
• Differential with gain: A selectable gain modifies the input signal level before ADC
conversion.
6.2 Summary
Two bit fields are linked for conversion mode selection: INPUTMODE[1:0] and
CONVMODE, respectively, in the CTRL and CTRLB registers.
Unsigned mode is available only if differential mode is not selected.
Table 6-1. Conversion modes
INPUTMODE[1:0]
Conversion mode
CONVMODE = 1
CONVMODE = 0
Signed mode
Unsigned mode
00
Internal
Yes
Yes
01
Single ended
Yes
Yes
10
Differential without gain
Yes
_
11
Differential with gain
Yes
_
AVR XMEGA A, B, and D offer the same four conversion modes. Differences appear
only on the available inputs/outputs (DAC, DMA, etc.).
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6.3 Positive Input Pin
The ADC positive input pins are connected to analog input pins or internal analog
pins. The value programmed in the MUXPOS[3:0] field (see MUXCTRL register)
selects the input pin.
The list of available input pins depends on the Atmel AVR XMEGA family.
Table 6-2. Positive input pin selection
AVR XMEGA A specific
AVR XMEGA B and D specific
Single-ended
Internal
Differential without gain
MUXPOS[3:0]
12
Differential with gain
AVR XMEGA A
AVR XMEGA B and D
AVR XMEGA A
AVR XMEGA B and D
0000
Temperature reference
Temperature reference
ADC0
ADC0
0001
Bandgap voltage
Bandgap voltage
ADC1
ADC1
0010
VCC/10
VCC/10
ADC2
ADC2
0011
DAC output
_
ADC3
ADC3
0100
_
_
ADC4
ADC4
0101
_
_
ADC5
ADC5
0110
_
_
ADC6
ADC6
0111
_
_
ADC7
ADC7
1000
_
_
_
ADC8
1001
_
_
_
ADC9
1010
_
_
_
ADC10
1011
_
_
_
ADC11
1100
_
_
_
ADC12
1101
_
_
_
ADC13
1110
_
_
_
ADC14
1111
_
_
_
ADC15
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6.4 Negative Input Pin
In differential mode with gain or without gain, the ADC negative inputs are not
connected to the same analog input pins.
In single ended mode, the ADC negative input pin is always connected to ground.
If internal mode or single-ended mode are selected, the MUXNEG[1:0] fields are not
used.
Table 6-3. Negative input pin selection
MUXNEG[1:0]
Differential without
Differential with
gain
gain
Internal
Single Ended
00
ADC0
ADC4
_
_
01
ADC1
ADC5
_
_
10
ADC2
ADC6
_
_
11
ADC3
ADC7
_
_
7 Conversion mode description
The Atmel AVR XMEGA A, B, and D ADCs offer the same conversion modes.
7.1 Unsigned Single-ended mode
In unsigned mode, the conversion range is from ground to the reference voltage.
The resolution is 12 bits. The theoretical measurement step is Vref/4096.
A negative offset appears around ground measurement.
The approximate value corresponding to ground is around 200. This value
corresponds to the digital result of ∆V (0.05 * 4096).
∆V exists to allow zero-crossing detection.
Figure 7-1. Unsigned single-ended mode range
4095
Vref - ΔV
ΔV ~= 0.05*Vref
ADC positive input pin excursion
~200
0
GND
- ΔV
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Advantage:
This mode offers full resolution (12 bits) and zero-crossing detection.
Drawback:
VREF not reached (only VREF - ∆V).
Domain:
This mode allows using the device for Atmel QMatrix detection.
Applications with limited excursions and maximum accuracy are the
target (temperature sensor, battery supervision, multimeter).
7.2 Signed single-ended mode
In signed mode, the conversion range is from Vref to -Vref.
The resolution is 11 bits. The theoretical measurement step is (2 * Vref)/4096.
The ADC negative input is connected to ground in this mode. The positive input
voltage value is limited by the pad: VIL min (input low voltage).
In this mode, the full range is not reachable.
Figure 7-2. Signed single ended mode range
2047
Vref
ADC positive input pin excursion
0
-2048
-0.5
-Vref
Advantage:
This mode offers a full range from GND to VREF.
Drawback:
The mode resolution is 11 bits (plus sign). The negative voltage is
limited by the microcontroller pad.
Domain:
Applications needing full range and zero detection (for example, motor
control).
7.3 Signed Differential Input (with x2 x4 x8 x16 x32 x64 gain/ without gain)
The input voltage is connected between positive and negative ADC inputs. The
resolution is 11bits (plus sign).
When the gain stage is used, the input signal is amplified before it reaches the ADC.
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Figure 7-3. Signed differential mode range
2047
Vref/gain
0
ADC differential input excursion
-2048
-Vref/gain
When differential mode is selected, the input excursion on positive and negative
inputs is as described in Figure 7-4.
Figure 7-4. Input voltage range
Vref
Vp
os
Vref/2
eg
Vn
Vin
t
0
Advantage:
Vin
Allows measurement of small amplitude signals with 11bits (plus sign)
resolution. Differential input removes noise from the ground reference.
Drawback:
Available only in differential mode.
Domain:
Sensors with small signal amplitude, differential signals.
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8 Conversion rate
The major difference between the Atmel AVR XMEGA A and the Atmel AVR XMEGA
B and D is the conversion rate:
•
•
2Msps for AVR XMEGA A (pipelined ADC)
200ksps for AVR XMEGA B and D (cyclic ADC)
8.1 Cyclic ADC
This value corresponds to the max ADC frequency divided by the number of ADC
cycles for a complete conversion:
F ADC max = 1.4MHz
Propagation delay for a 12-bit conversion = 7 ADC cycles => 200ksps
8.2 Pipelined ADC
The propagation delay for a single conversion is the same as that for a cyclic ADC.
The main difference is that four channels can share the 12 basic elements. The
maximum conversion rate is a complete conversion every ADC cycle.
FADC max = 2MHz => Propagation delay = 2Msps
Propagation delay for a 12-bit conversion = 1 ADC cycle = 2Msps
9 Voltage references
Voltage references are identical on all Atmel AVR XMEGA devices.
The bandgap is a fixed and accurate voltage. This voltage allows monitoring VCC.
The Atmel AVR XMEGA B offers an additional reference of VCC/2. This voltage
reference, combined with x0.5 gain, offers a rail-to-rail excursion from VCC to -VCC (see
Figure 10-1).
Table 9-1. Voltage references.
AVR XMEGA B
AVR XMEGA A
AVR XMEGA D
16
REFSEL[2:0]
REFSEL[1:0]
Selection
Description
000
00
INT1V
Internal 1V (Bandgap)
001
01
INTVCC
Internal VCC/1.6
010
10
AREFA
External reference on AREF pin on PORTA
011
11
AREFB
External reference on AREF pin on PORTB
100
-
INTVCC/2
Internal VCC/2
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10 Additional features
10.1 Software Selectable Gain
Gain is only available in differential mode.
If gain is used, the propagation time increases.
This is for instance a complete channel sweep triggered by a single event, or an
event re-synchronized conversion to achieve a very accurate timing for the
conversion.
Table 10-1. Propagation delay
Gain
Single Ended
Remark
Differential without gain
Differential with gain
x0.5
+0.5
x1
0
x2
+0.5
x4
+1
X8
+1.5
x16
+2
x32
+2.5
X64
+3
AVR XMEGA B specific
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10.2 x0.5 Gain (only for AVR XMEGA B)
This gain is useful for rail-to-rail measurements in differential mode.
The x0.5 gain allows having a complete signal conversion from maximum value to
minimum value.
This feature is important for measurements needing accuracy on the entire signal
excursion.
Figure 10-1. x0.5 gain range
2047
2*Vref
Vref
0
ADC differential input excursion
-Vref
-2048
-2*Vref
Advantage:
Allows a rail to rail measurement without distortion around VREF and -VREF.
Drawback:
Available only on AVR XMEGA B.
Domain:
Sinusoidal signals, motor control.
10.3 DMA transfer
It is possible to use DMA to move the ADC results directly to memory or peripherals
when conversions are done. The TRIGSRC[7:0] register selects which trigger source
is used for triggering a transfer on the DMA channel.
ADCA or ADCB are proposed as DMA input for the Atmel AVR XMEGA A.
In addition to providing a DMA transfer request for each ADC channel, the ADC can
be set up to provide a combined request for all channels. The combined request is
decided according to the DMASEL value (see CTRLA register).
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10.4 Scan mode
AVR XMEGA A, B and D ADCs offer a scan mode. This feature is only available on
CH0. Scan mode is controlled by SCAN register.
Table 10-2. SCAN register
SCAN
INPUTOFFSET[3:0]
INPUTSCAN[3:0]
When INPUTSCAN is set to a value other than zero, the number of inputs scanned is
(INPUTSCAN + 1). The next conversion is performed on input (INPUTOFFSET +
MUXPOS) and INPUTOFFSET is incremented after each conversion.
The rate of conversion for CH0 is the same, regardless of the INPUTSCAN setting.
For example, if the initial values are INPUTOFFSET=0, INPUTSCAN=5 and
MUXPOS=2, and then five conversions using START would be needed to cycle
through input 2-7.
10.5 ADC Calibration
The production signature row offers several bytes for ADC calibration. The ADC is
calibrated during production testing, and the calibration value must be loaded from
the signature row into the ADC registers (CAL registers).
The calibration corrects the capacitor mismatch of the switched capacitor technology.
For the AVR XMEGA A, the calibration registers are composed of two 8-bit registers
with 12 bits used for the calibration value. The 12-bit value is composed of three
groups of 4 bits each. Each group corresponds to a basic element of the pipelined
structure. Only the first three basic elements of the pipelined ADC are re-calibrated.
The calibration value must be loaded from the signature row into the CALH and CAL
ADC registers.
For the Atmel AVR XMEGA B and D, the calibration register is composed of one 8-bit
register. The 8-bit value is composed of two groups of 4 bits each. Each group
corresponds to a switch of the cyclic structure. The calibration value must be loaded
from the signature row into the CAL ADC register.
The ADC driver available in Atmel AVR Software Framework (ASF) has an init
function included for management of the calibration registers.
This is not a calibration for gain error and offset error.
Table 10-3. ADC calibration in production signature row
AVR XMEGA A
AVR XMEGA B
AVR XMEGA D
ADCACAL0
Yes
Yes
Yes
ADCACAL1
Yes
_
_
ADCBCAL0
Yes
Yes
_
ADCBCAL1
Yes
Yes
_
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10.6 Temperature sensor calibration
The signature row contains a 12-bit ADCA value from a temperature measurement
done in production test. This measurement corresponds to 85°C.
This measurement can be used for temperature sensor calibration.
Table 10-4. Temperature sensor calibration in production signature row
20
AVR XMEGA A
AVR XMEGA B
AVR XMEGA D
TEMPSENSE0
Yes
Yes
Yes
TEMPSENSE1
Yes
Yes
Yes
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11 Conclusion
The following tables help in the selection of the ADC, depending on the application. A
study of the application gives the ADC type to use (Table 11-2), after selection of
conversion mode (Table 11-1).
Table 11-1. Conversion mode selection
Unsigned
Signed
Signed differential
Signed differential
Single-ended
Single-ended
without gain
with gain
Resolution
12-bit
11-bit + sign
11-bit + sign
11-bit + sign
Advantage
Zero-crossing
No ∆V.
No external scaling system
No external scaling system
Rail to rail conversion with
x0.5 gain
Drawback
VREF out of
Negative voltage
excursion.
limited by pad
_
_
Signal with excursion
Signal with scaling needed
∆V not fixed.
Application
QMatrix
Positive signals
between Vref and -Vref
The major interest of XMEGA™ A comes from the pipelined structure to manage
several conversions in parallel.
Table 11-2. ADC type selection
A
B
D
What is the max
2Msps with 4
200ksps / Number of
200ksps / Number of
propagation on
simultaneous
channels
channels
each channel?
channels
ADC result
Yes
_
_
Manual sweep
Manual sweep
Yes
_
_
_
Yes
_
transferred with
DMA
SWEEP mode
DAC output for
Automatic sweep
ADC internal
input
x0.5 gain
21
8378A-AVR-10/2011
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8378A-AVR-10/11