ATtiny43U Atmel Corporation, ATtiny43U Datasheet - Page 126

• Manufacturer Part Number: ATtiny43U
• Manufacturer: Atmel Corporation

Specifications of ATtiny43U

• Flash (kbytes): 4 Kbytes
• Pin Count: 20
• Max. Operating Frequency: 8 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 16
• Ext Interrupts: 16
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 4
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 0.25
• Eeprom (bytes): 64
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 0.7 to 5.5
• Operating Voltage (vcc): 0.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 4
• Pwm Channels: 4
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

16.13 Register Description
16.13.1
126
ATtiny43U
ADMUX – ADC Multiplexer Selection Register
perature sensor is enabled, the ADC converter can be used in single conversion mode to
measure the voltage over the temperature sensor.
The measured voltage has a linear relationship to the temperature as described in
The sensitivity is approximately 1 LSB /
ibration. Typically, the measurement accuracy after a single temperature calibration is ±
assuming calibration at room temperature. Better accuracies are achieved by using two
temperature points for calibration.
Table 16-2.
The values described in
temperature sensor output voltage varies from one chip to another. To be capable of achieving
more accurate results the temperature measurement can be calibrated in the application soft-
ware. The sofware calibration can be done using the formula:
where ADCH and ADCL are the ADC data registers, k is the fixed slope coefficient and T
temperature sensor offset. Typically, k is very close to 1.0 and in single-point calibration the
coefficient may be omitted. Where higher accuracy is required the slope coefficient should be
evaluated based on measurements at two temperatures.
• Bit 7 – Res: Reserved Bit
This bit is reserved and must always be written zero.
• Bit 6 – REFS: Reference Selection Bit
This bit selects the voltage reference for the ADC, as shown in
is changed during a conversion, the change will not go in effect until this conversion is complete
(ADIF in ADCSR is set).
Table 16-3.
• Bits 5:3 – Res: Reserved Bits
These bits are reserved and will always read zero.
Bit
0x07 (0x27)
Read/Write
Initial Value
Temperature
ADC
T = k * [(ADCH << 8) | ADCL] + T
REFS
0
1
Temperature vs. Sensor Output Voltage (Typical Case)
Voltage Reference Selections for ADC
R/W
7
–
0
REFS
Table 16-2
R/W
Voltage Reference Selection
V
Internal 1.1V Voltage Reference.
6
0
CC
used as analog reference.
230 LSB
-40 °C
R
5
0
–
are typical values. However, due to process variation the
°
C and the accuracy depends on the method of user cal-
OS
R
4
–
0
R
3
–
0
300 LSB
+25 °C
MUX2
R/W
2
0
Table 16-3 on page
MUX1
R/W
1
0
MUX0
R/W
0
0
370 LSB
+85 °C
8048B–AVR–03/09
126. If this bit
Table 16-2
OS
ADMUX
10°
is the
C,