MSC8113 Reference Manual, Rev. 0
14-2
Freescale Semiconductor
Direct Slave Interface (DSI)
The DSI stops prefetching data and flushes the read buffer when one of the following conditions
is met:
The host read access address is not consecutive to previous access address. A consecutive
address is the last a 4 bytes in 32-bit bus mode and the last a 8 bytes in
64-bit bus mode. For burst read accesses, the consecutive address is the last address (the
address of the first beat of the burst) + 32 bytes for both 32-bit and 64-bit bus mode.
A host write access has begun (to ensure data coherency).
In Synchronous mode, a burst read access starts after a single read access, or a single read
access starts after a read burst access.
Note:
Using the prefetch mechanism, the host reads the data from the read buffer instead of
directly from memory. It can therefore read data that is not up-to-date.
To reduce latency for accesses to the MSC8113 internal or external address space, writes by the
DSI are done via the write buffer. Write accesses to the DSI registers bypass the write buffer;
therefore, you can change the DSI control registers and immediately perform the next access with
the guarantee that this access is controlled by the new setting programmed in the DSI control
registers. Overflow can occur only during broadcast accesses because there is no
HTA
signal to
validate the write access (See Section 14.3.5). To preserve data coherency, a read access to the
DSI stalls until all previous write accesses in the write buffer are complete.
When a host writes memory buffers to the device internal or external memory from the DSI port
and then generates a Buffer Ready interrupt into one of the device
IRQ
s, the interrupt may reach
its destination before the buffer contents are correctly placed inside the memory because the DSI
first writes to its internal write buffer and not directly to the memory. To avoid this situation, the
host should perform the write accesses, then a read access (for example, a read of the DSI status
register), and only then issue the Buffer Ready interrupt. Because the read access flushes the
write buffer into the memory, the interrupt cannot arrive before the end of the last write (the
interrupt occurs only at the end of the read access).
Note:
For the description of the DSI external signals, see Chapter 3, External Signals.
Note:
In systems that include a host device that connects to the MSC8113 through the DSI
and the MSC8113 connects to other MSC8113, MSC8122, or MSC8126 devices
through the system bus, all devices on the system bus must allow 64-bit read access for
reads initiated by the host device. This is because any read access by the host through
the DSI is translated by the MSC8113 DSI block as a 64-bit access.
Summary of Contents for MSC8113
Page 1: ...MSC8113 Reference Manual Tri Core 16 Bit Digital Signal Processor MSC8113RM Rev 0 May 2008 ...
Page 20: ...MSC8113 Reference Manual Rev 0 xx Freescale Semiconductor Contents ...
Page 28: ...MSC8113 Reference Manual Rev 0 xxviii Freescale Semiconductor ...
Page 56: ...MSC8113 Reference Manual Rev 0 1 28 Freescale Semiconductor MSC8113 Overview ...
Page 76: ...MSC8113 Reference Manual Rev 0 2 20 Freescale Semiconductor SC140 Core Overview ...
Page 134: ...MSC8113 Reference Manual Rev 0 4 30 Freescale Semiconductor System Interface Unit SIU ...
Page 168: ...MSC8113 Reference Manual Rev 0 6 18 Freescale Semiconductor Boot Program ...
Page 180: ...MSC8113 Reference Manual Rev 0 7 12 Freescale Semiconductor Clocks ...
Page 260: ...MSC8113 Reference Manual Rev 0 8 80 Freescale Semiconductor Memory Map ...
Page 300: ...MSC8113 Reference Manual Rev 0 9 40 Freescale Semiconductor Extended Core ...
Page 304: ...MSC8113 Reference Manual Rev 0 10 4 Freescale Semiconductor MQBus and M2 Memory ...
Page 308: ...MSC8113 Reference Manual Rev 0 11 4 Freescale Semiconductor SQBus ...
Page 590: ...MSC8113 Reference Manual Rev 0 17 46 Freescale Semiconductor Interrupt Processing ...
Page 614: ...MSC8113 Reference Manual Rev 0 18 24 Freescale Semiconductor Debugging ...
Page 622: ...MSC8113 Reference Manual Rev 0 19 8 Freescale Semiconductor Internal Peripheral Bus IPBus ...
Page 724: ...MSC8113 Reference Manual Rev 0 21 32 Freescale Semiconductor UART ...
Page 920: ...MSC8113 Reference Manual Rev 0 25 150 Freescale Semiconductor Ethernet Controller ...
Page 1171: ...MSC8113 Reference Manual Rev 0 Freescale Semiconductor C 61 EF wait_rts P 01077FFC 9F rts 71 ...
Page 1172: ...MSC8113 Reference Manual Rev 0 C 62 Freescale Semiconductor MSC8113 Boot Code ...
Page 1202: ...MSC8113 Reference Manual Rev 0 Index 30 Freescale Semiconductor Index ...