AMIS-30624 I2C Microstepping Motordriver
Data Sheet
16.0 I2C Bus Description
16.1 General Description
AMIS-30624 uses a simple bi-directional 2-wire bus for efficient inter-ic control. This bus is called the Inter IC or I2C-bus.
Features include:
• Only two bus lines are required; a serial data line (SDA) and a serial clock line (SCK).
• Each device connected to the bus is software addressable by a unique address and simple master/slave relationships exists at
all times; master can operate as master-transmitter or as master receiver.
• Serial, 8-bit oriented, bi-directional data transfers can be made up to 400 kbit/s.
• On-chip filtering rejects spikes on the bus data line to preserve data integrity.
• No need to design bus interfaces because I2C-bus interface is already integrated on-chip.
• IC’s can be added to or removed from a system without affecting any other circuits on the bus.
16.2 Concept
The I2C-bus consists of two wires, serial data (SDA) and serial clock (SCK), carrying information between the devices connected on the
bus. Each device connected to the bus is recognized by a unique address and operates as either a transmitter or receiver, depending
on the function of the device. AMIS-30624 can both receive and transmit data. In addition to transmitters and receivers, devices can
also be considered as masters or slaves when performing data transfers. AMIS-30624 is a slave device. See Table 30.
Table 29: Definition of I2C –bus Terminology
Term
Description
Transmitter
Receiver
Master
The device which sends data on the bus
The device which receives data from the bus
The device which initiates a transfer, generates clock signals and terminates a transfer
The devices addressed by a master
Slave
Synchronization
Procedure to synchronizer the clock signals of two or more devices
Motordriver_2
AMIS-30624
Motordriver_4
AMIS-30624
Micro-
controller
SDA
SCL
Motordriver_1
AMIS-30624
Motordriver_3
AMIS-30624
PC20070217.1
Figure 23: Example of an I2C-bus Configuration Using One Microcontroller and Four Slaves
Figure 23 highlights the master-slave and receiver-transmitter relationships to be found on the I2C-bus. It should be noted that these
relationships are not permanent but only depend on the direction of data transfer at that time. The transfer of data would proceed as
follows:
1) Suppose the microcontroller wants to send information to motordriver_1:
• Microcontroller (master) addresses motordriver_1 (slave)
• Microcontroller (master-transmitter) sends data to motordriver_1 (slave-receiver)
• Microcontroller terminates the transfer
AMI Semiconductor – Apr. 2007, Rev 3.1, M-20664-003
39
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