ATTINY26-16PI Atmel, ATTINY26-16PI Datasheet - Page 80

• Manufacturer Part Number: ATTINY26-16PI
• Description: IC AVR MCU 2K 16MHZ IND 20-DIP
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY26-16PI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 16
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 11x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 20-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Universal Serial
Interface – USI
Overview
80
ATtiny26(L)
The Universal Serial Interface, or USI, provides the basic hardware resources needed for serial
communication. Combined with a minimum of control software, the USI allows significantly
higher transfer rates and uses less code space than solutions based on software only. Interrupts
are included to minimize the processor load. The main features of the USI are:
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A simplified block diagram of the USI is shown on Figure 44.
Figure 44. Universal Serial Interface, Block Diagram
The 8-bit Shift Register is directly accessible via the data bus and contains the incoming and
outgoing data. The register has no buffering so the data must be read as quickly as possible to
ensure that no data is lost. The most significant bit is connected to one of two output pins
depending of the wire mode configuration. A transparent latch is inserted between the serial reg-
ister output and output pin, which delays the change of data output to the opposite clock edge of
the data input sampling. The serial input is always sampled from the Data Input (DI) pin indepen-
dent of the configuration.
The 4-bit counter can be both read and written via the data bus, and can generate an overflow
interrupt. Both the serial register and the counter are clocked simultaneously by the same clock
source. This allows the counter to count the number of bits received or transmitted and generate
an interrupt when the transfer is complete. Note that when an external clock source is selected
the counter counts both clock edges. In this case the counter counts the number of edges, and
not the number of bits. The clock can be selected from three different sources: the SCK pin,
Timer 0 overflow, or from software.
The Two-wire clock control unit can generate an interrupt when a start condition is detected on
the Two-wire bus. It can also generate wait states by holding the clock pin low after a start con-
dition is detected, or after the counter overflows.
Two-wire Synchronous Data Transfer (Master or Slave, f
Three-wire Synchronous Data Transfer (Master, f
Data Received Interrupt
Wakeup from Idle Mode
In Two-wire Mode: Wake-up from All Sleep Modes, Including Power-down Mode
Two-wire Start Condition Detector with Interrupt Capability
USIDR
USISR
USICR
2
4-bit Counter
3
2
1
0
3
2
1
0
D Q
LE
[1]
SCKmax
TIM0 OVF
0
1
= f
SCLmax
CK
/2, Slave f
Two-wire Clock
Control Unit
= f
CK
/16)
CLOCK
HOLD
SCKmax
PB1
PB0
= f
PB2
CK
DO
(Output only)
DI/SDA
(Input/Open Drain)
/4)
SCK/SCL
(Input/Open Drain)
1477K–AVR–08/10