ATA5773-DK1 Atmel, ATA5773-DK1 Datasheet - Page 144

• Manufacturer Part Number: ATA5773-DK1
• Description: BOARD XMITTER FOR ATA5773 315MHZ
• Manufacturer: Atmel
• Type: Transmitterr

Specifications of ATA5773-DK1

• Frequency: 315MHz
• Maximum Frequency: 315 MHz
• Supply Voltage (max): 4 V
• Supply Voltage (min): 2 V
• Supply Current: 9 mA
• Product: RF Development Tools
• For Use With/related Products: ATA5773
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

144
Atmel ATA5771/73/74
The ADC module contains a prescaler, which generates an acceptable ADC clock frequency
from any CPU frequency above 100 kHz. The prescaling is set by the ADPS bits in ADCSRA.
The prescaler starts counting from the moment the ADC is switched on by setting the ADEN
bit in ADCSRA. The prescaler keeps running for as long as the ADEN bit is set, and is contin-
uously reset when ADEN is low.
When initiating a single ended conversion by setting the ADSC bit in ADCSRA, the conversion
starts at the following rising edge of the ADC clock cycle.
A normal conversion takes 13 ADC clock cycles. The first conversion after the ADC is
switched on (ADEN in ADCSRA is set) takes 25 ADC clock cycles in order to initialize the ana-
log circuitry.
The actual sample-and-hold takes place 1.5 ADC clock cycles after the start of a normal con-
version and 14.5 ADC clock cycles after the start of an first conversion. When a conversion is
complete, the result is written to the ADC Data Registers, and ADIF is set. In Single Conver-
sion mode, ADSC is cleared simultaneously. The software may then set ADSC again, and a
new conversion will be initiated on the first rising ADC clock edge.
When Auto Triggering is used, the prescaler is reset when the trigger event occurs. This
assures a fixed delay from the trigger event to the start of conversion. In this mode, the sam-
ple-and-hold takes place two ADC clock cycles after the rising edge on the trigger source
signal. Three additional CPU clock cycles are used for synchronization logic.
In Free Running mode, a new conversion will be started immediately after the conversion
completes, while ADSC remains high. For a summary of conversion times, see
page
Figure 4-62. ADC Timing Diagram, First Conversion (Single Conversion Mode)
Cycle Number
ADC Clock
ADEN
ADSC
ADIF
ADCH
ADCL
146.
1
2
MUX and REFS
Update
12
13
14
15
Sample & Hold
16
First Conversion
17
18
19
20
21
22
Conversion
Complete
23
24
25
Sign and MSB of Result
Next
Conversion
1
LSB of Result
Table 4-48 on
9137E–RKE–12/10
2
MUX and REFS
Update
3