AMIS-30624 Datasheet, PDF (41/56 Pages) AMI SEMICONDUCTOR – I2C Microstepping Motordriver

AMIS-30624
15.5.3. Clock Generation
The master generates the clock on the SCK line to transfer messages on the I²C-bus. Data is only valid during the HIGH period of the
clock.
15.6 Data Formats with 7-bit Addresses
Data transfers follow the format shown in Figure 29. After the START condition (S), a slave address is sent. This address is 7-bit long
followed by an eighth bit which is a data direction bit (R/W) – a ‘zero’ indicates a transmission (WRITE), a ‘one’ indicates a request for
data (READ). A data transfer is always terminated by a STOP condition (P) generated by the master.
START
SDA
PC20070217.6
STOP
SCK
1-7
8
9
1-7
8
9
1-7
8
9
START
condition ^ADDRESS
R/W
ACK
DATA
ACK
Figure 29: A Complete Data Transfer
DATA
STOP
ACK
condition
However, if a master still wishes to communicate on the bus, it can generate a repeated START (Sr) and address another slave without
first generating a STOP condition. Various combinations of read/write formats are then possible within such a transfer.
15.6.1. Data Transfer Formats
15.6.1.1 Writing Data to AMIS-30624
When writing to AMIS-30624, the master-transmitter transmits to slave-receiver and the transfer direction is not changed. A complete
transmission consists of:
• Start condition
• The slave address (7-bit)
• Read/Write bit (‘0’ = write)
• Acknowledge bit
• Any further data bytes are followed by an acknowledge bit. The acknowledge bit is used to signal a correct reception of the
data to the transmitter. In this case the AMIS-30624 pulls the SDA line to ‘0’. The AMIS-30624 reads the incoming data at SDA
on every rising edge of the SCK signal
• Stop condition to finish the transmission
•
S Slave Address R/W A
Data
A
Data
AP
"0" = WRITE
N bytes + Acknowledge
Master to AMIS-30624
AMIS-30624 to Master
S = Start condition
P = Stop condition
A = Acknowledge (SDA = LOW)
A = No Acknowledge (SDA = HIGH)
Figure 30: Master Writing Data to AMIS-30624
PC20070219.3
Some commands for the AMIS-30624 are supporting eight bytes of data, other commands are transmitting two bytes of data. See Table
30.
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