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TC1784
Peripheral Control Processor (PCP)
User´s Manual
10-42
V1.1, 2011-05
PCP, V2.09
Note: This scheme also limits the number of Channel Programs that can be invoked.
Note: FPI PRAM write accesses to PRAM are unaffected by this protection.
10.7.2.2 Protected Channel PRAM Protection
To ensure that an Unprotected Channel Program cannot corrupt the PRAM assigned to
a protected channel program it is necessary to protect the PRAM space used by the
protected channels from instruction executed by non-protected channels. The PCP
provides a protection scheme which prevents corruption of a programmable range of
locations at the base of PRAM by writes generated by a non-protected channel. This
region is termed the “Protected Channel PRAM”. Protection is enabled via PPROT.ENI
and the size of the protected region is controlled by PPROT.PSIZE. This function is
controlled by the PCP_PPROT register (
“PRAM Protection Register, PCP_PPROT”
).
Whenever a Unprotected Channel Program executes a PRAM write instruction (and
protection is enabled) the target address will be examined to determine whether it lies
within the Protected Channel PRAM region. If the address lies within the region then the
PRAM write will not take place and the PCP will exit the channel with an IOP (Illegal
Operation) error.
Note: FPI PRAM write accesses to PRAM are unaffected by this protection.
10.8
FPI Interface
The PCP operates both as an FPI Master and an FPI Slave.
10.8.1
Operation as an FPI Master
The PCP generates FPI read and write transactions in response to execution of PCP FPI
instructions. The PCP can generate Byte, Half-word and Word single transactions and
bursts of length two, four and eight. All FPI transactions are generated in Supervisor
Mode.
For High Integrity Systems it is necessary to prevent the PCP from generating unwanted
FPI writes to critical locations in the event of a PCP malfunction. To address this problem
a Memory Protection feature is provided to control the address range that can be written
to by the PCP. The scheme is based around a user definable FPI address window. Along
with defining the window base address and size the user can select whether:-
•
Writes are allowed only to addresses that are within the window (Limit).
•
Writes are allowed only to addresses that are outside the window (Exclude).
Whenever the PCP executes an FPI instruction that will result in an FPI write accesses
the destination address is checked to ensure that it is to an allowed address. If a write
access is to an address that is not allowed then the write will not take place and the PCP
will exit the channel with an IOP (Illegal Operation) error.
Summary of Contents for TC1784
Page 1: ...User s Manual V1 1 2011 05 Microcontrollers TC1784 32 Bit Single Chip Microcontroller ...
Page 3: ...User s Manual V1 1 2011 05 Microcontrollers TC1784 32 Bit Single Chip Microcontroller ...
Page 950: ...TC1784 Direct Memory Access Controller DMA User s Manual 11 132 V1 1 2011 05 DMA V3 03 ...
Page 1949: ...TC1784 General Purpose Timer Array GPTA v5 User s Manual 21 297 V1 1 2011 05 GPTA v5 V1 14 ...
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