attiny167-esxz ATMEL Corporation, attiny167-esxz Datasheet - Page 193

• Manufacturer Part Number: attiny167-esxz
• Description: 8-bit Avr 8-bit Microcontroller Microcontroller With 16k Bytes In-system Programmable Flash And Lin Controller
• Manufacturer: ATMEL Corporation

17.8.1
17.8.2
17.8.3
17.9
7728A–AUTO–07/08
Temperature Measurement
Single Ended Conversion
Unipolar Differential Conversion
Bipolar Differential Conversion
For single ended conversion, the result is:
where V
Table 17-4 on page 195
0x3FF represents the selected voltage reference minus one LSB. The result is presented in one-
sided form, from 0x3FF to 0x000.
If differential channels and an unipolar input mode are used, the result is:
where V
and V
197). The voltage on the positive pin must always be larger than the voltage on the negative pin
or otherwise the voltage difference is saturated to zero. The result is presented in one-sided
form, from 0x000 (0
As default the ADC converter operates in the unipolar input mode, but the bipolar input mode
can be selected by writing the BIN bit in the ADCSRB register to one. In the bipolar input mode
two-sided voltage differences are allowed and thus the voltage on the negative input pin can
also be larger than the voltage on the positive input pin. If differential channels and a bipolar
input mode are used, the result is:
where V
and V
0x200 (-512
However, if the signal is not bipolar by nature (9 bits + sign as the 10th bit), this scheme loses
one bit of the converter dynamic range. Then, if the user wants to perform the conversion with
the maximum dynamic range, the user can perform a quick polarity check of the result and use
the unipolar differential conversion with selectable differential input pair. When the polarity check
is performed, it is sufficient to read the MSB of the result (ADC9 in ADCH register). If the bit is
one, the result is negative, and if this bit is zero, the result is positive.
The temperature measurement is based on an on-chip temperature sensor that is coupled to a
single ended. MUX[4..0] bits in ADMUX register enables the temperature sensor. The internal
REF
REF
IN
POS
POS
the selected voltage reference. The result is presented in two’s complement form, from
the selected voltage reference (see
is the voltage on the selected input pin and V
d
is the voltage on the positive input pin, V
is the voltage on the positive input pin, V
) through 0x000 (+0
d
) to 0x3FF (+1023
and
ADC
ADC
Table 17-5 on page
d
) to 0x1FF (+511
=
=
(
------------------------------------------------------- - GAIN
(
---------------------------------------------------- - GAIN
ADC
V
V
d
POS
). The GAIN is either 8x or 20x.
POS
–
=
–
V
V
V
V
V
--------------------------
REF
Table 17-4 on page 195
REF
NEG
NEG
IN
V
⋅
REF
) 1024
d
1024
197). 0x000 represents analog ground, and
) 512
). The GAIN is either 8x or 20x.
⋅
⋅
NEG
NEG
REF
the voltage on the negative input pin,
⋅
the voltage on the negative input pin,
⋅
the selected voltage reference (see
and
Table 17-5 on page
ATtiny167
193