A000047 Arduino, A000047 Datasheet - Page 241

• Manufacturer Part Number: A000047
• Description: MCU, MPU & DSP Development Tools Mega2560
• Manufacturer: Arduino
• Series: -r
• Type: MCUr

Specifications of A000047

• Processor To Be Evaluated: ATmega2560
• Interface Type: USB, I2C, SPI
• Dimensions: 4 in x 2.1 in
• Operating Supply Voltage: 5 V
• Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ATmega2560

23. 2-wire Serial Interface
23.1
23.2
23.2.1
2549M–AVR–09/10
Features
2-wire Serial Interface Bus Definition
TWI Terminology
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The 2-wire Serial Interface (TWI) is ideally suited for typical microcontroller applications. The
TWI protocol allows the systems designer to interconnect up to 128 different devices using only
two bi-directional bus lines, one for clock (SCL) and one for data (SDA). The only external hard-
ware needed to implement the bus is a single pull-up resistor for each of the TWI bus lines. All
devices connected to the bus have individual addresses, and mechanisms for resolving bus
contention are inherent in the TWI protocol.
Figure 23-1. TWI Bus Interconnection
The following definitions are frequently encountered in this section.
Table 23-1.
Term
Master
Slave
Transmitter
Receiver
Simple yet Powerful and Flexible Communication Interface, only two Bus Lines needed
Both Master and Slave Operation Supported
Device can Operate as Transmitter or Receiver
7-bit Address Space Allows up to 128 Different Slave Addresses
Multi-master Arbitration Support
Up to 400 kHz Data Transfer Speed
Slew-rate Limited Output Drivers
Noise Suppression Circuitry Rejects Spikes on Bus Lines
Fully Programmable Slave Address with General Call Support
Address Recognition Causes Wake-up When AVR is in Sleep Mode
SDA
SCL
TWI Terminology
Description
The device that initiates and terminates a transmission. The Master also generates the
SCL clock.
The device addressed by a Master.
The device placing data on the bus.
The device reading data from the bus.
Device 1
Device 2
ATmega640/1280/1281/2560/2561
Device 3
........
Device n
V
CC
R1
R2
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