AMIMON AMN11310 WHDI, Datasheet

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Interfaces
Version 0.4
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3.3 Management Buses and Connectors
3.3.1 Two-Wire Serial Bus Interface
The WHDI application observes and controls the AMN11310 via a Two-Wire interface and an interrupt line
connecting the application microcontroller and the AMN11310 MAC microcontroller. The protocol of the Two-Wire
bus for the WHDI application/MAC interface is described in the following sections.
The Two-Wire bus is bidirectional and, as its name implies, has only two wires: a Serial Clock Line (SCL) and a
Serial Data Line (SDA). The Two-Wire architecture includes master and slave devices. The master initiates a
data transfer on the bus and generates the clock signal. The AMN11310 MAC operates as a slave device. Each
slave device is recognized by a unique address and can operate as either a receive-only device or a transmitter
with the ability to both receive and send information.
Application
MicroController
(Two-Wire Master)
WHDI MAC
(Two-Wire Slave)
SDA
SCL
Figure 7: Two-Wire Application/MAC Connection
On top of the Two-Wire low level operation described in sections 3.3.1.3 and 3.3.1.4, the WHDI application and
the MAC microcontrollers communicate with each other in a defined protocol, which avoids all possibilities of
confusion. The protocol defines command oriented transactions between the application and the WHDI MAC.
Each Two-Wire command has a predefined data byte length and is defined to be exactly one Two-Wire
transaction long.
3.3.1.1 Two-Wire Timing
Generally, the clock frequency of the bus is dictated by the slowest device on the Two-Wire interface. However,
the selected MAC supports the 100 KHz SCL frequency rate.
Refer to STM32F Two-wire reference application note for detailed description of the physical protocol and timing.
http://www.st.com/stonline/products/literature/ds/13587.pdf, pp 55-59.
3.3.1.2 Device Addresses
The MAC device address may be altered by two jumpers on VDU/VSU board.
Table 6: Device Addresses
Device Address
MAC uC 0x62 or 0x82 or 0x90 or 0x70
(Board configuration dependant)
Alternatively, the device address can be set in the MAC SW in advance.