7. I
2
C Interface > SMBus Support
163
Tsi578 User Manual
June 6, 2016
Integrated Device Technology
www.idt.com
7.6.1
Incoming Mailbox
To send data to the processor/host, an external I
2
C master writes data to the incoming mailbox register,
EXI2C_MBOX_IN, through the Tsi578 slave interface. When the Stop condition is seen (indicating the
external master is completed writing to the mailbox), the slave interface sets the IMB_FLAG in the
C Slave Access Status Register”
, and the processor/host is interrupted to let it
know the mailbox is full by setting IMB_FULL status in the
optional interrupt can be sent to the Interrupt Controller if enabled in IMB_FULL of the
In response to the interrupt, the processor/host reads the incoming mailbox to retrieve the data. This
process of reading the register clears the IMB_FLAG in the status register. The external I
2
C master can
poll the status register through the slave interface, and when it sees the flag go to 0, it knows the
processor/host has read the data and it is safe to write more. If the external I
2
C master writes more data
before earlier data is read, the old data is overwritten. In this case, depending on timing, the
processor/host may read a mixture of old and new data.
7.6.2
Outgoing Mailbox
To send data to an external I
2
C master, the processor/host writes data to the outgoing mailbox register,
EXI2C_MBOX_OUT. This sets the OMB_FLAG in the
, which the external I
2
C master can poll through the slave interface. When the flag goes up
(1), the external I
2
C master reads the outgoing mailbox register through the slave interface.
Once the Stop condition is seen (indicating the external master has completed reading the mailbox), the
slave interface clears the OMB_FLAG in the status register, EXI2C_ACC_STAT, and interrupts the
processor/host with an OMB_EMPTY in the
to let it know the mailbox
has been read and it is safe to write more data. An optional interrupt can be sent to the Interrupt
Controller if enabled in OMB_EMPTY of
. If the processor/host writes
more data to the mailbox before the data is read, the old data is overwritten. In this case, depending on
timing, the external I
2
C master may read a mixture of old and new data.
7.7
SMBus Support
The I
2
C Interface provides limited functionality for SMBus applications. The Tsi578 can act as an
SMBus Host and communicate to other SMBus slave devices through a subset of the SMBus protocols
(see
).
As a host, the Tsi578 cannot effectively receive a SMBus Host Notify message sent by another
non-host SMBus device acting as a master. In addition, the Tsi578 cannot effectively act as a non-host
SMBus device and receive commands from an external SMHost. Although the Tsi578 responds as a
slave to the SMBus protocols, they are processed relative to the slave interface functionality. The
SMBus command code is assumed to be a peripheral address, and data written to or read through the
slave interface will depend on the peripheral address selected.
Содержание Tsi578
Страница 1: ...IDT Tsi578 Serial RapidIO Switch User Manual June 6 2016 Titl ...
Страница 20: ...About this Document 20 Tsi578 User Manual June 6 2016 Integrated Device Technology www idt com ...
Страница 102: ...4 Internal Switching Fabric Packet Queuing 102 Tsi578 User Manual June 6 2016 Integrated Device Technology www idt com ...
Страница 228: ...11 Signals Pinlist and Ballmap 228 Tsi578 User Manual June 6 2016 Integrated Device Technology www idt com ...
Страница 504: ...B Clocking P_CLK Programming 504 Tsi578 User Manual June 6 2016 Integrated Device Technology www idt com ...
Страница 526: ...Index 526 Tsi578 User Manual June 6 2016 Integrated Device Technology www idt com ...