ATTINY44-20SSU Atmel, ATTINY44-20SSU Datasheet - Page 125

• Manufacturer Part Number: ATTINY44-20SSU
• Description: IC MCU AVR 4K FLASH 20MHZ 14SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY44-20SSU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 12
• Program Memory Size: 4KB (2K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Cpu Family: ATtiny
• Device Core: AVR
• Device Core Size: 8b
• Frequency (max): 20MHz
• Interface Type: SPI/USI
• Total Internal Ram Size: 256Byte
• # I/os (max): 12
• Number Of Timers - General Purpose: 2
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• On-chip Adc: 8-chx10-bit
• Instruction Set Architecture: RISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 14
• Package Type: SOIC
• For Use With: ATAVRISP2 - PROGRAMMER AVR IN SYSTEM
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

14.5.2
14.5.3
8006K–AVR–10/10
USIBR – USI Data Buffer
USISR – USI Status Register
Instead of reading data from the USI Data Register the USI Buffer Register can be used. This
makes controlling the USI less time critical and gives the CPU more time to handle other pro-
gram tasks. USI flags as set similarly as when reading the USIDR register.
The content of the USI Data Register is loaded to the USI Buffer Register when the transfer has
been completed.
The Status Register contains interrupt flags, line status flags and the counter value.
• Bit 7 – USISIF: Start Condition Interrupt Flag
When two-wire mode is selected, the USISIF Flag is set (to one) when a start condition has
been detected. When three-wire mode or output disable mode has been selected any edge on
the SCK pin will set the flag.
If USISIE bit in USICR and the Global Interrupt Enable Flag are set, an interrupt will be gener-
ated when this flag is set. The flag will only be cleared by writing a logical one to the USISIF bit.
Clearing this bit will release the start detection hold of USCL in two-wire mode.
A start condition interrupt will wakeup the processor from all sleep modes.
• Bit 6 – USIOIF: Counter Overflow Interrupt Flag
This flag is set (one) when the 4-bit counter overflows (i.e., at the transition from 15 to 0). If the
USIOIE bit in USICR and the Global Interrupt Enable Flag are set an interrupt will also be gener-
ated when the flag is set. The flag will only be cleared if a one is written to the USIOIF bit.
Clearing this bit will release the counter overflow hold of SCL in two-wire mode.
A counter overflow interrupt will wakeup the processor from Idle sleep mode.
• Bit 5 – USIPF: Stop Condition Flag
When two-wire mode is selected, the USIPF Flag is set (one) when a stop condition has been
detected. The flag is cleared by writing a one to this bit. Note that this is not an interrupt flag.
This signal is useful when implementing two-wire bus master arbitration.
• Bit 4 – USIDC: Data Output Collision
This bit is logical one when bit 7 in the USI Data Register differs from the physical pin value. The
flag is only valid when two-wire mode is used. This signal is useful when implementing Two-wire
bus master arbitration.
• Bits 3:0 – USICNT3:0: Counter Value
These bits reflect the current 4-bit counter value. The 4-bit counter value can directly be read or
written by the CPU.
Bit
0x10 (0x30)
Read/Write
Initial Value
Bit
0x0D (0x2D)
Read/Write
Initial Value
USISIF
R/W
MSB
7
0
R
7
0
USIOIF
R/W
6
0
R
6
0
USIPF
R/W
5
0
R
5
0
USIDC
R
4
0
R
4
0
USICNT3
R/W
3
0
R
3
0
USICNT2
R/W
2
0
R
2
0
ATtiny24/44/84
USICNT1
R/W
1
0
R
1
0
USICNT0
LSB
R/W
R
0
0
0
0
USIBR
USISR
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