MEGA128CAN Datasheet, PDF (278/413 Pages) ATMEL Corporation – Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER

Table 100. Correlation Between Input Voltage and Output Codes
V_ADCn
V_ADCm + V_REF /GAIN
V_ADCm + 0.999 V_REF /GAIN
V_ADCm + 0.998 V_REF /GAIN
...
Read code
0x1FF
0x1FF
0x1FE
...
Corresponding decimal value
511
511
510
...
V_ADCm + 0.001 V_REF /GAIN
V_ADCm
V_ADCm - 0.001 V_REF /GAIN
...
0x001
1
0x000
0
0x3FF
-1
...
...
V_ADCm - 0.999 V_REF /GAIN
V_ADCm - V_REF /GAIN
0x201
0x200
-511
-512
Example 1:
– 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.
Writing zero to ADLAR right adjusts the result: ADCL = 0x70, ADCH = 0x02.
Example 2:
– 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.
Writing zero to ADLAR right adjusts the result: ADCL = 0x00, ADCH = 0x29.
278 AT90CAN128
4250E–CAN–12/04