at43usb355 ATMEL Corporation, at43usb355 Datasheet - Page 65

• Manufacturer Part Number: at43usb355
• Description: At43usb355 Full-speed Usb Microcontroller With Embedded Hub, Adc And Pwm
• Manufacturer: ATMEL Corporation

Scanning Multiple
Channels
2603G–USB–04/06
Table 23. ADC Prescaler Selections
ADC Data Register – ADCL and ADCH
When an ADC conversion is complete, the result is found in these two registers. In Free Run
Mode, it is essential that both registers are read, and that ADCL is read before ADCH.
Since change of analog channels is always delayed until a conversion is finished, the Free
Run Mode can be used to scan multiple channels without interrupting the converter. Typically,
the ADC Conversion Complete interrupt will be used to perform the channel shift. However,
the user should take the following fact into consideration:
The interrupt triggers once the result is ready to be read. In Free Run Mode, the next conver-
sion will start immediately when the interrupt triggers. If ADMUX is changed after the interrupt
triggers, the next conversion has already started and the old setting is used.
Initial Value
Read/Write
$03 ($23)
$24 ($44)
Bit
ADPS2
0
0
0
0
1
1
1
1
ADC7
R
7
–
0
ADC6
R
6
–
0
ADPS1
ADC5
R
0
0
1
1
0
0
1
1
5
–
0
ADC4
R
4
–
0
ADC3
R
3
–
0
ADPS0
0
1
0
1
0
1
0
1
ADC2
R
2
–
0
AT43USB355
ADC9
ADC1
R
1
0
Division Factor
ADC8
ADC0
128
16
32
64
R
0
0
2
2
4
8
ADCH
ADCL
65