AT90PWM81-16SF Atmel, AT90PWM81-16SF Datasheet - Page 216

• Manufacturer Part Number: AT90PWM81-16SF
• Description: IC MCU AVR 8K FLASH ISP 20SOIC
• Manufacturer: Atmel
• Series: AVR® 90PWM Lightingr

Specifications of AT90PWM81-16SF

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI
• Peripherals: Brown-out Detect/Reset, PWM, WDT
• Number Of I /o: 16
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b; D/A 1x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 20-SOIC (7.5mm Width)
• For Use With: ATSTK600-SOIC - STK600 SOCKET/ADAPTER FOR SOIC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

17.8
17.8.1
216
ADC Register Description
AT90PWM81
ADC Multiplexer Register – ADMUX
Table 17-2.
Example 1:
Example 2:
The ADC of the AT90PWM81 is controlled through 3 different registers. The ADCSRA and The ADC-
SRB registers which are the ADC Control and Status registers, and the ADMUX which allows to select
the Vref source and the channel to be converted.
The conversion result is stored on ADCH and ADCL register which contain respectively the most signifi-
cant bits and the less significant bits.
Bit
Read/Write
Initial Value
V
V
V
...
V
V
V
...
V
V
V
ADCn
ADCm
ADCm
ADCm
ADCm
ADCm
ADCm
ADCm
ADCm
– ADMUX = 0xED (ADC3 - ADC2, 10x gain, 2.56V reference, left adjusted result)
– Voltage on ADC3 is 300 mV, voltage on ADC2 is 500 mV.
– ADCR = 512 * 10 * (300 - 500) / 2560 = -400 = 0x270
– ADCL will thus read 0x00, and ADCH will read 0x9C.
– ADMUX = 0xFB (ADC3 - ADC2, 1x gain, 2.56V reference, left adjusted result)
– Voltage on ADC3 is 300 mV, voltage on ADC2 is 500 mV.
– ADCR = 512 * 1 * (300 - 500) / 2560 = -41 = 0x029.
– ADCL will thus read 0x40, and ADCH will read 0x0A.
+ 0.999 V
+ 0.998 V
+ 0.001 V
- 0.001 V
- 0.999 V
- V
+ V
Writing zero to ADLAR right adjusts the result: ADCL = 0x70, ADCH = 0x02.
Writing zero to ADLAR right adjusts the result: ADCL = 0x00, ADCH = 0x29.
REF
REF
/GAIN
7
REFS1
R/W
0
/GAIN
Correlation Between Input Voltage and Output Codes
REF
REF
REF
REF
REF
/GAIN
/GAIN
/GAIN
/GAIN
/GAIN
6
REFS0
R/W
0
R/W
5
ADLAR
0
Read code
0x1FE
0x1FF
0x1FF
0x3FF
0x001
0x000
0x201
0x200
...
...
4
-
-R
0
3
MUX3
R/W
0
511
511
-1
Corresponding decimal value
510
...
1
0
...
-511
-512
2
MUX2
R/W
0
R/W
1
MUX1
0
0
MUX0
R/W
0
7734P–AVR–08/10
ADMUX