ATMEGA328-MUR Atmel, ATMEGA328-MUR Datasheet - Page 222

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ATMEGA328-MUR

Manufacturer Part Number
ATMEGA328-MUR
Description
IC MCU AVR 32K FLASH 32QFN
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheets

Specifications of ATMEGA328-MUR

Core Processor
AVR
Core Size
8-Bit
Speed
20MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
23
Program Memory Size
32KB (16K x 16)
Program Memory Type
FLASH
Eeprom Size
1K x 8
Ram Size
2K x 8
Voltage - Supply (vcc/vdd)
1.8 V ~ 5.5 V
Data Converters
A/D 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
32-VQFN Exposed Pad, 32-HVQFN, 32-SQFN, 32-DHVQFN
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
21.5
21.5.1
21.5.2
8271C–AVR–08/10
Overview of the TWI Module
SCL and SDA Pins
Bit Rate Generator Unit
The TWI module is comprised of several submodules, as shown in
drawn in a thick line are accessible through the AVR data bus.
Figure 21-9. Overview of the TWI Module
These pins interface the AVR TWI with the rest of the MCU system. The output drivers contain a
slew-rate limiter in order to conform to the TWI specification. The input stages contain a spike
suppression unit removing spikes shorter than 50 ns. Note that the internal pull-ups in the AVR
pads can be enabled by setting the PORT bits corresponding to the SCL and SDA pins, as
explained in the I/O Port section. The internal pull-ups can in some systems eliminate the need
for external ones.
This unit controls the period of SCL when operating in a Master mode. The SCL period is con-
trolled by settings in the TWI Bit Rate Register (TWBR) and the Prescaler bits in the TWI Status
Register (TWSR). Slave operation does not depend on Bit Rate or Prescaler settings, but the
CPU clock frequency in the Slave must be at least 16 times higher than the SCL frequency. Note
ATmega48A/48PA/88A/88PA/168A/168PA/328/328
Slew-rate
Address Match Unit
Arbitration detection
Control
START / STOP
Address Comparator
Address Register
Control
SCL
(TWAR)
Spike
Filter
Bus Interface Unit
Spike Suppression
Address/Data Shift
Register (TWDR)
Slew-rate
Control
SDA
Status Register
Ack
Spike
Filter
(TWSR)
State Machine and
Control Unit
Status control
Bit Rate Generator
Control Register
Bit Rate Register
Figure
Prescaler
(TWCR)
(TWBR)
21-9. All registers
222

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