ATMEGA32U4-MUR Atmel, ATMEGA32U4-MUR Datasheet - Page 231

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ATMEGA32U4-MUR

Manufacturer Part Number
ATMEGA32U4-MUR
Description
MCU AVR 16K FLASH 16MHZ 44VQFN
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheet

Specifications of ATMEGA32U4-MUR

Core Processor
AVR
Core Size
8-Bit
Speed
16MHz
Connectivity
I²C, SPI, UART/USART, USB
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
26
Program Memory Size
32KB (16K x 16)
Program Memory Type
FLASH
Eeprom Size
1K x 8
Ram Size
2.5K x 8
Voltage - Supply (vcc/vdd)
2.7 V ~ 5.5 V
Data Converters
A/D 12x10b
Oscillator Type
External
Operating Temperature
-40°C ~ 85°C
Package / Case
44-VQFN
Lead Free Status / RoHS Status
Lead free / RoHS Compliant

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
ATMEGA32U4-MUR
Manufacturer:
UCC
Quantity:
1 001
20.6
20.6.1
20.6.2
7766F–AVR–11/10
TWI Register Description
TWI Bit Rate Register – TWBR
TWI Control Register – TWCR
The TWINT Flag is set in the following situations:
• Bits 7..0 – TWI Bit Rate Register
TWBR selects the division factor for the bit rate generator. The bit rate generator is a frequency
divider which generates the SCL clock frequency in the Master modes. See
Unit” on page 229
The TWCR is used to control the operation of the TWI. It is used to enable the TWI, to initiate a
Master access by applying a START condition to the bus, to generate a Receiver acknowledge,
to generate a stop condition, and to control halting of the bus while the data to be written to the
bus are written to the TWDR. It also indicates a write collision if data is attempted written to
TWDR while the register is inaccessible.
• Bit 7 – TWINT: TWI Interrupt Flag
This bit is set by hardware when the TWI has finished its current job and expects application
software response. If the I-bit in SREG and TWIE in TWCR are set, the MCU will jump to the
TWI Interrupt Vector. While the TWINT Flag is set, the SCL low period is stretched. The TWINT
Flag must be cleared by software by writing a logic one to it. Note that this flag is not automati-
cally cleared by hardware when executing the interrupt routine. Also note that clearing this flag
starts the operation of the TWI, so all accesses to the TWI Address Register (TWAR), TWI Sta-
tus Register (TWSR), and TWI Data Register (TWDR) must be complete before clearing this
flag.
• Bit 6 – TWEA: TWI Enable Acknowledge Bit
The TWEA bit controls the generation of the acknowledge pulse. If the TWEA bit is written to
one, the ACK pulse is generated on the TWI bus if the following conditions are met:
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
• After the TWI has transmitted a START/REPEATED START condition.
• After the TWI has transmitted SLA+R/W.
• After the TWI has transmitted an address byte.
• After the TWI has lost arbitration.
• After the TWI has been addressed by own slave address or general call.
• After the TWI has received a data byte.
• After a STOP or REPEATED START has been received while still addressed as a Slave.
• When a bus error has occurred due to an illegal START or STOP condition.
TWBR7
TWINT
R/W
R/W
7
0
7
0
for calculating bit rates.
TWBR6
TWEA
R/W
R/W
6
0
6
0
TWBR5
TWSTA
R/W
R/W
5
0
5
0
TWBR4
TWSTO
R/W
R/W
4
0
4
0
TWBR3
TWWC
R/W
R
3
0
3
0
TWBR2
TWEN
R/W
R/W
2
0
2
0
TWBR1
R/W
ATmega16/32U4
R
1
0
1
0
TWBR0
TWIE
R/W
R/W
0
0
0
0
“Bit Rate Generator
TWBR
TWCR
231

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