ATtiny261 Atmel Corporation, ATtiny261 Datasheet - Page 108

• Manufacturer Part Number: ATtiny261
• Manufacturer: Atmel Corporation

Specifications of ATtiny261

• Flash (kbytes): 2 Kbytes
• Pin Count: 20
• Max. Operating Frequency: 20 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 4
• 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: 11
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 0.12
• Eeprom (bytes): 128
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 6
• Input Capture Channels: 1
• Pwm Channels: 6
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

12.10.1
12.10.2
12.11 Accessing 10-Bit Registers
12.11.1
108
ATtiny261/461/861
Fault Protection Trigger Source
Noise Canceler
Reusing the temporary high byte register
pins. The Fault Protection Enable (FPEN1) is automatically cleared at the same system clock as
the COM1nx bits are cleared.
If the Fault Protection Interrupt Enable bit (FPIE1) is set, a Fault Protection interrupt is generated
and the FPEN1 bit is cleared. Alternatively the FPEN1 bit can be polled by software to figure out
when the Timer/Counter has entered to Fault Protection mode.
The main trigger source for the Fault Protection unit is the external interrupt pin (INT0). Alterna-
tively the Analog Comparator output can be used as trigger source for the Fault Protection unit.
The Analog Comparator is selected as trigger source by setting the Fault Protection Analog
Comparator (FPAC1) bit in the Timer/Counter1 Control Register (TCCR1D). Be aware that
changing trigger source can trigger a Fault Protection mode. Therefore it is recommended to
clear the FPF1 flag after changing trigger source, setting edge detector or enabling the Fault
Protection.
Both the external interrupt pin (INT0) and the Analog Comparator output (ACO) inputs are sam-
pled using the same technique as with the T0 pin (see
detectors are also identical but when the noise canceler is enabled additional logic is activated
before the edge detector, increasing the propagation delay with four system clock cycles.
An Input Capture can also be triggered by software by controlling the port of the INT0 pin.
The noise canceler uses a simple digital filtering technique to improve noise immunity. Consecu-
tive samples are monitored in a pipeline four units deep. The signal going to the edge detecter is
allowed to change only when all four samples are equal.
The noise canceler is enabled by setting the Fault Protection Noise Canceler (FPNC1) bit in
Timer/Counter1 Control Register D (TCCR1D). When enabled, the noise canceler introduces an
additional delay of four system clock cycles to a change applied to the input.
The noise canceler uses the system clock directly and is therefore not affected by the prescaler.
If 10-bit values are written to the TCNT1 and OCR1A/B/C/D registers, the 10-bit registers can be
byte accessed by the AVR CPU via the 8-bit data bus using two read or write operations. The
10-bit registers have a common 2-bit Timer/Counter1 High Byte Register (TC1H) that is used for
temporary storing of the two MSBs of the 10-bit access. The same TC1H register is shared
between all 10-bit registers. Accessing the low byte triggers the 10-bit read or write operation.
When the low byte of a 10-bit register is written by the CPU, the high byte stored in the TC1H
register, and the low byte written are both copied into the 10-bit register in the same clock cycle.
When the low byte of a 10-bit register is read by the CPU, the high byte of the 10-bit register is
copied into the TC1H register in the same clock cycle as the low byte is read.
To do a 10-bit write, the high byte must be written to the TC1H register before the low byte is
written. For a 10-bit read, the low byte must be read before the high byte.
If writing to more than one 10-bit register where the high byte is the same for all registers written,
then the high byte only needs to be written once. However, note that the same rule of atomic
operation described previously also applies in this case.
Figure 11-3 on page
74). The edge
2588E–AVR–08/10