Protocol, Ams0805wah, Start condition – Rainbow Electronics DAB-GPS-C01 User Manual
Page 9: Stop condition, Sda scl start stop, Motion sensor
AMS0805WAH
MOTION SENSOR
9
Protocol
●
Transaction Rules
Each data transferred on the SDA is accompanied by a pulse on the clock signal. The
data on the SDA must be stable when the clock is high. The only exception is for generating start
and stop. The master initiates and terminates a data transmission.
Start condition
: To start reading/writing operation, it is necessary to generate a start condition by
switching the SDA input from high level to low level when the SCL input is high
level.
Stop condition
: To stop reading/writing operation, it is necessary to generate stop condition by
switching the SDA input from low level to high level when the SCL input is high
level. When the stop condition is generated, the operation is stopped, the data
is processed and the system enters in standby mode.
●
Single-Byte Write Sequence
The Single Byte Write Sequence is composed of 3 bytes of 9 bits, the 9
th
bit being the
acknowledgement. It starts by a start condition and ends by a stop condition. The first byte is the
Slave Address, the second is the Register Address and the third is the Data Byte. The LSB of the
Slave Code byte is the R/W indicator.
SDA
SCL
Start
Stop
1
0
1
0
0
X
W
A
SCL
SDA
Slave address
0
S
6
5
4
3
2
1
0
A
Command
7
6
5
4
3
2
1
0
A
Data
7
P
MSB
LSB
MSB
LSB
MSB
LSB
A
A
A
SDA SLAVE
SDA MASTER
1
0
1
0
0
X
W
0
S
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
7
P
MASTER Transmit & SLAVE Receive