MSC8113 Reference Manual, Rev. 0
9-6
Freescale Semiconductor
Extended Core
9.2.1.2 Memory Contention and Priority
Each memory group has four I/O ports: L, P, Xa, and Xb, which are accessed by the local bus,
internal program bus, and the two internal data buses, respectively. The two data buses,
connected to ports Xa and Xb, can accesses the same memory group simultaneously. However,
the local bus (L port) and the program bus (P port) cannot access the same 32 KB memory group
simultaneously; nor can either bus access the same 32 KB memory group as a data bus. If such
access is attempted in the same cycle, a contention causes a lost cycle in the SC140 core. Except
for dual data bus access, each memory module serves only one bus in a cycle. The use of memory
interleaving and the fact that there is no contention on the same line of a module minimize the
probability of a contention when close data is addressed with the Xa and Xb buses. In summary:
Group contention occurs between the X, P, and L ports. There is no contention between
Xa and Xb to the same group.
Module contention occurs between Xa and Xb. There is no contention on the same line.
9.2.2 Errors and Exceptions
The QBus control unit detects contentions and errors on the internal core buses and outputs
exception signals to the interrupt controller. See Chapter 17, Interrupt Processing.
9.2.2.1 Errors
Errors generate interrupts using the
NMI
inputs to the interrupt controller, as follows:
Bus Error. When an address on the internal bus does not match any physical address in the
internal memory space, a bus error occurs and
NMI4
is generated internally. Such accesses
include implicit accesses by pipelined program fetches. In rare cases, the bus error
interrupt does not occur after an access to a non-valid address in internal memory. If this
problem occurs during software development, place a debug instruction before the NMI4
handler and transfer control to the debugger to search for the root cause of the problem.
Misaligned program. SC140 instructions are 16 bits (two bytes) and must be aligned. If
the address on the program bus is not 16-bit aligned, a misaligned program error occurs
and
NMI3
is generated internally.
9.2.2.2 Exceptions
Exceptions assert the interrupt request lines of the interrupt controller and can be masked. The
contention exceptions are mainly used for debug and profiling and can be masked otherwise. The
exceptions generate the following interrupts:
Misaligned data. When the address on the data buses (Xa or Xb) is misaligned with the
data size, a misaligned data exception occurs and
IRQ13
is generated internally.
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 ...