MPC563XM Reference Manual, Rev. 1
782
Freescale Semiconductor
Preliminary—Subject to Change Without Notice
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Microcode request, through microinstruction field CIRC (see
Interrupt and Data Transfer Requests
”). This Global Exception source is flagged by bits
MGE1(Engine 1) and MGE2(Engine 2) in register ETPUMCR. The cause of this illegal state is
application-dependent. The microcode may write an error code into the SPRAM to indicate the
cause of the exception, for instance.
Global Exceptions cannot be directly disabled within eTPU, except by disabling its sources (MISC and
microcode), and it is cleared by writing 1 to the GEC bit in ETPUMCR. Clearing Global Exception clears
all Global Exception source status bits (ILF1, ILF2, SCMMISF, MGE1, MGE2). If GEC is written 1 at the
same time any of the sources issues a Global Exception, both the interrupt and the status bit of that source
remains asserted. The assertion of Global Exception by one of the sources above does not prevent the
others from asserting it too, so any number of them, in any combination, can be flagged.
NOTE
There can be a race between the clear of a Global Exception and occurrence
of a new set condition, such that the set happens just before the clear and
cannot be sensed by the Host. Therefore, Global Exceptions cannot be used
as a normal interrupt source: it should only be used for emergency
procedures.
23.4.2.2.2
Interrupt and Data Transfer Request Overflow
If a Channel Interrupt was issued, its status bit is still set, and microcode issues another Channel Interrupt,
the Interrupt Overflow status bit is set for that channel. Interrupt Overflow status can be checked by the
Host in Channel Status register ETPUCxSCR bit CIOS (
Section 23.3.7.2, “ETPUCxSCR - eTPU Channel
), mirrored in register ETPUCIOSR (
Section 23.3.6.3, “ETPUCIOSR - eTPU
Channel Interrupt Overflow Status Register
). Interrupt Overflow status is not cleared automatically when
Interrupt Status is cleared. The same mechanism and respective registers (ETPUCDTROSR) are available
for Data Transfer Requests.
If interrupt is set and cleared at the same time, set prevails and overflow is not altered (keeps the same state
as it was before, asserted or not).
Global Exception has no overflow status.
23.4.2.3
Parameter Access
23.4.2.3.1
Parameter Access Widths
From the Host side the SPRAM address space is mapped in bytes, and each 32-bit parameter occupies 4
contiguous, aligned bytes. The Host can read/write the SPRAM by 8-, 16-, or 32-bit accesses in aligned
addresses.
In 32-bit access, Host can access all 32 bits or only the lower 24 bits with an automatic sign extension (see