atmega163l ATMEL Corporation, atmega163l Datasheet - Page 80

• Manufacturer Part Number: atmega163l
• Description: Atmega163 8-bit Avr Microcontroller With 16k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Two-wire Serial
Interface (Byte
Oriented)
80
ATmega163(L)
The Two-wire Serial Interface supports bi-directional serial communication. It is
designed primarily for simple but efficient integrated circuit (IC) control. The system is
comprised of two lines, SCL (Serial Clock) and SDA (Serial Data) that carry information
between the ICs connected to them. Various communication configurations can be
designed using this bus. Figure 49 shows a typical Two-wire Serial Bus configuration.
Any device connected to the bus can be master or slave. Note that all AVR devices con-
nected to the bus must be powered to allow any bus operation.
Figure 49. Two-wire Serial Bus Configuration
The Two-wire Serial Interface supports Master/Slave and Transmitter/Receiver opera-
tion at up to 217 kHz bus clock rate. The Two-wire Serial Interface has hardware
support for 7-bit addressing, but is easily extended to, e.g., a 10-bit addressing format in
software. When the Two-wire Serial Interface is enabled (TWEN in TWCR is set), a
glitch filter is enabled for the input signals from the pins PC0 (SCL) and PC1 (SDA), and
the output from these pins is slew-rate controlled. The Two-wire Serial Interface is byte
oriented. The operation of the Two-wire Serial Bus is shown as a pulse diagram in Fig-
ure 50, including the START and STOP conditions and generation of ACK signal by the
bus receiver.
Figure 50. Two-wire Serial Bus Timing Diagram
The block diagram of the Two-wire Serial Interface is shown in Figure 51.
SDA
SCL
CONDITION
START
Device 1
MSB
1
2
Device 2
7
R/W
BIT
8
Device 3
ACK
9
FROM RECEIVER
ACKNOWLEDGE
.......
1
2
Device n
8
ACK
9
R1
R2
STOP CONDITION
REPEATED START
CONDITION
1142E–AVR–02/03
V
SCL
SDA
CC