EAGLE
PRELIMINARY
Ver 1.3
3.27.3 DATA TRANSFER FORMAT
All data length on SDA line is 8 bits wide. The number of bytes transmitted per transfer has no limits.
The address field is located one byte after Start condition. TWI controller shall transmit the address field when operating
as master. ACK bit is included after all bytes are transferred. All transfers always start with MSB bit of data or address..
Write Mode Format with 7-bit Addresses
S
Slave Address 7bits R/W A
DATA(1Byte)
A P
"0"
Data Transferred
(Write)
(Data + Acknowledge)
Read Mode Format with 7-bit Addresses
S
Slave Address 7bits R/W A
DATA(1Byte)
A P
"1"
(Read)
Data Transferred
(Data + Acknowledge)
NOTES:
1. S:Start, rS:Repeat Start, P:Stop, A:Acknoledge
2. :From Master to Slave, from Slave to Master
Figure 3-46 TWI-Bus Interface Data Format
3.27.4 START AND STOP CONDITION
The Start condition enables the the TWI Controller to start data transfer while the Stop condition stops the data transfer
operation. Start condition is triggered by a high to low change on SDA line when SCL is high. Stop condition is generated by
a low to high change on SDA line when SCL is high. After the Start condition, TWI bus transitions to busy state. After Stop
condition, TWI bus enters release state.
SDA
MSB
Acknowledgement Signal
from Receiver
Acknowledgement Signal
from Receiver
1
7
8
9
2
SCL
Start
Stop
ACK
Byte Complete, Interrupt within
Receiver
Clock Line Held Low While
Interrupts are Serviced
Figure 3-47 Data Transfer on the TWI-Bus
Beijing Peak Microtech Co.Ltd.
CONFIDENTIAL
194
ETC [ ETC ]
