ATxmega128A1 Atmel Corporation, ATxmega128A1 Datasheet - Page 293

• Manufacturer Part Number: ATxmega128A1
• Manufacturer: Atmel Corporation

Specifications of ATxmega128A1

• Flash (kbytes): 128 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 78
• Ext Interrupts: 78
• Usb Speed: No
• Usb Interface: No
• Spi: 12
• Twi (i2c): 4
• Uart: 8
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 4
• Resistive Touch Screen: No
• Dac Channels: 4
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 8
• Eeprom (bytes): 2048
• Self Program Memory: YES
• External Bus Interface: 1
• Dram Memory: sdram
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.6 to 3.6
• Operating Voltage (vcc): 1.6 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 8
• Output Compare Channels: 24
• Input Capture Channels: 24
• Pwm Channels: 24
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

25.4
8077H–AVR–12/09
ADC Channels
temperature sensor, and the value is store in the production calibration row and can be used for
temperature sensor calibration.
The bandgap voltage is an accurate voltage reference inside the microcontroller that is the
source for other internal voltage references.
V
Thus, V
The output from the DAC module can also be measured by the ADC. It is the output directly from
the DAC, and not the Sample and Hold (S/H) outputs, that is available for the ADC.
Some of the internal signals need to be turned on specifically before they can be used mea-
sured. Refer to the manual for these modules for details of how to turn them on. The sample rate
for the internal signals is lower than the maximum speed for the ADC, refer to the ADC charac-
teristics in the device data sheets for details on sample rate of the internal signals.
When measuring the internal signals, the negative input is connected to internal ground in
signed mode.
Figure 25-6. Internal measurements in signed mode
In unsigned mode the negative input is connected to a fixed value which is half of the voltage ref-
erence (VREF) minus a fixed offset as it is for single ended unsigned input. Refer to
11 on page 296
Figure 25-7. Internal measurements in unsigned mode
To facilitate the use of the ADC, the design implements four separate MUX control registers with
corresponding result registers. The MUX/result register pair is called an ADC channel, and this
is shown in
different input sources, use different start conversion triggers, and they use different events and
interrupts. The result is stored in different result registers.
CC
can be measured directly by scaling it down and dividing it by 10 before the ADC input.
CC
of 1.8 V will be measured as 0.18 V and V
Figure 25-1 on page
BANDGAP REF
BANDGAP REF
VCC SCALED
VCC SCALED
for details.
TEMP REF
TEMP REF
DAC
DAC
290. Each ADC channel can be set up individually to measure
VREF
2
−
Δ
V
CC
of 3.6 V will be measured as 0.36 V.
+
+
-
-
ADC
ADC
XMEGA A
Figure 25-
293