ATtiny2313 Atmel Corporation, ATtiny2313 Datasheet - Page 113

• Manufacturer Part Number: ATtiny2313
• Manufacturer: Atmel Corporation

Specifications of ATtiny2313

• 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: 18
• Ext Interrupts: 18
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• 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: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

Internal Clock
Generation – The
Baud Rate Generator
2543L–AVR–08/10
Figure 54. Clock Generation Logic, Block Diagram
Signal description:
Internal clock generation is used for the asynchronous and the synchronous master modes of
operation. The description in this section refers to
The USART Baud Rate Register (UBRR) and the down-counter connected to it function as a
programmable prescaler or baud rate generator. The down-counter, running at system clock
(f
the UBRRL Register is written. A clock is generated each time the counter reaches zero. This
clock is the baud rate generator clock output (= f
baud rate generator clock output by 2, 8 or 16 depending on mode. The baud rate generator out-
put is used directly by the Receiver’s clock and data recovery units. However, the recovery units
use a state machine that uses 2, 8 or 16 states depending on mode set by the state of the
UMSEL, U2X and DDR_XCK bits.
Table 48
the UBRR value for each mode of operation using an internally generated clock source.
Table 48. Equations for Calculating Baud Rate Register Setting
Note:
osc
Operating Mode
Asynchronous Normal
mode (U2X = 0)
Asynchronous Double
Speed mode (U2X = 1)
Synchronous Master
mode
txclk
rxclk
xcki
xcko
fosc
), is loaded with the UBRR value each time the counter has counted down to zero or when
DDR_XCK
1. The baud rate is defined to be the transfer rate in bit per second (bps)
XCK
contains equations for calculating the baud rate (in bits per second) and for calculating
Pin
Transmitter clock (Internal Signal).
Receiver base clock (Internal Signal).
Input from XCK pin (internal Signal). Used for synchronous slave operation.
Clock output to XCK pin (Internal Signal). Used for synchronous master
operation.
XTAL pin frequency (System Clock).
xcko
xcki
OSC
Down-Counter
Prescaling
Register
UBRR
Sync
BAUD
BAUD
BAUD
Equation for Calculating
Baud Rate
=
UBRR+1
=
=
fosc
-------------------------------------- -
16 UBRR
Detector
---------------------------------- -
8 UBRR
---------------------------------- -
2 UBRR
UCPOL
Edge
(
(
(
f
f
f
OSC
OSC
OSC
(1)
/2
+
+
+
1
1
Figure
1
osc
)
)
)
/(UBRR+1)). The Transmitter divides the
/4
54.
Equation for Calculating
UBRR
UBRR
UBRR
/2
UBRR Value
=
=
=
DDR_XCK
----------------------- - 1
16BAUD
------------------- - 1
8BAUD
------------------- - 1
2BAUD
f
f
f
U2X
OSC
OSC
OSC
0
1
0
1
–
–
–
0
1
1
0
UMSEL
txclk
rxclk
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