ATA5771-DK1 Atmel, ATA5771-DK1 Datasheet - Page 152

• Manufacturer Part Number: ATA5771-DK1
• Description: BOARD XMITTER FOR ATA5771 868MHZ
• Manufacturer: Atmel
• Type: Transmitterr

Specifications of ATA5771-DK1

• Frequency: 868MHz
• Maximum Frequency: 868 MHz
• Supply Voltage (max): 4 V
• Supply Voltage (min): 2 V
• Supply Current: 8.5 mA
• Product: RF Development Tools
• For Use With/related Products: ATA5771
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

4.20.10
4.20.10.1
152
Atmel ATA5771/73/74
Register Description
ADMUX – ADC Multiplexer Selection Register
The values described in
cess variation the temperature sensor output voltage varies from one chip to another. To be
capable of achieving more accurate results the temperature measurement can be calibrated in
the application software. The software calibration requires that a calibration value is measured
and stored in a register or EEPROM for each chip, as a part of the production test. The sof-
ware calibration can be done utilizing the formula:
where ADCn are the ADC data registers, k is a fixed coefficient and T
sensor offset value determined and stored into EEPROM as a part of the production test.To
obtain best accuracy the coefficient k should be measured using two temperature calibrations.
Using offset calibration, set k = 1.0, where k = (1024*1.07mV/°C)/1.1V~1.0 [1/°C].
• Bit 7:6 – REFS1:REFS0: Reference Selection Bits
These bits select the voltage reference for the ADC, as shown in
these bits are changed during a conversion, the change will not go in effect until this
conversion is complete (ADIF in ADCSR is set).
Special care should be taken when changing differential channels. Once a differential channel
has been selected, the stage may take as much as 25 ADC clock cycles to stabilize to the new
value. Thus conversions should not be started within the first 13 clock cycles after selecting a
new differential channel. Alternatively, conversion results obtained within this period should be
discarded.
The same settling time should be observed for the first differential conversion after changing
ADC reference (by changing the REFS1:0 bits in ADMUX).
If channels where differential gain is used ie. the gainstage, using V
AREF higher than (V
allowed to connect internal voltage reference to AREF pin, if an external voltage is being
applied to it already. Internal voltage reference is connected AREF pin when REFS1:0 is set to
value ‘11’.
Table 4-50.
Bit
0x07 (0x27)
Read/Write
Initial Value
REFS1
0
0
1
1
Voltage Reference Selections for ADC
REFS0
REFS1
R/W
7
0
0
1
0
1
CC
REFS0
- 1V) is not recommended, as this will affect ADC accuracy. It is not
Table 4-49 on page 151
R/W
Voltage Reference Selection
V
External Voltage Reference at PA0 (AREF) pin, Internal Voltage Reference
turned off.
Internal 1.1V Voltage Reference.
Reserved.
6
0
CC
T = {[(ADCH << 8) | ADCL] - TOS} / k
used as analog reference, disconnected from PA0 (AREF).
MUX5
R/W
5
0
MUX4
R/W
4
0
are typical values. However, due to the pro-
MUX3
R/W
3
0
MUX2
R/W
2
0
Table 4-50 on page
CC
MUX1
R/W
1
0
or an optional external
OS
is the temperature
MUX0
R/W
0
0
9137E–RKE–12/10
ADMUX
152. If