AMIS-30622_13 Datasheet, PDF (38/50 Pages) ON Semiconductor – I2C Micro-Stepping Motor Driver

AMIS−30622
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.
Data Formats with 7−bit Addresses
Data transfers follow the format shown in Figure 27. After
the START condition (S), a slave address is sent. This
START
SDA
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.
STOP
SCK
1−7
8
9
1−7
8
9
1−7
8
9
START
condition ^ADDRESS
R/W
ACK
DATA
ACK
Figure 27. 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.
Data Transfer Formats
Writing Data to AMIS−30622
When writing to AMIS−30622, 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−30622 pulls the
SDA line to ‘0’. The AMIS−30622 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 28. Master Writing Data to AMIS−30622
Some commands for the AMIS−30622 are supporting
eight bytes of data, other commands are transmitting two
bytes of data. See Table 25.
Reading Data to AMIS−30622
When reading data from AMIS−30622 two transmissions
are needed:
1. The first transmission consists of two bytes of
data:
♦ The first byte contains the slave address and the
write bit.
♦ The second byte contains the address of an
internal register in the
AMIS−30622. This internal
register address is stored in the circuit RAM.
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