
MBIST Instruction Register
ARM DDI 0402B
Copyright © 2007, 2008 ARM Limited. All rights reserved.
3-11
The doubleword select bits choose between the four 64-bit groups of RAM data before
sending the data to the 64-bit
MBISTDOUT[63:0]
bus. These two bits always map to
the Y-address counter bits between the column address and the block address.
Because this cache RAM has 256 rows per column, it uses eight bits for the row address,
this uses up all eight bits of the X-address counter. This RAM also contains two blocks
of 16 columns each, so it uses one bit for the block address. This maps to the most
significant bit of the Y-address counter. To correctly test this RAM, the Y-address field
must have a value of seven, MBIR[36:33] = b0111, and the X-address field must have
a value of eight, MBIR[40:37] = b1000. Values higher or lower than these produce
incorrect results.
Note
If the columns have fewer than 256 rows, you must still assign address bits to the row
address until all eight bits are used before assigning any to the block address. If the
cache RAM has more than 256 rows per column, then the additional bits must be
assigned to the block address. This does not have any detrimental effects on the test
coverage of the RAM.
Figure 3-3 shows how the MBIST controller builds the address output. The doubleword
select bits are the least significant two bits of the address. These two bits are ignored
unless the data RAM is selected. The exclusive OR of the two least significant bits of
the Y-address counter is the least significant bit of the column address for physical
addressing of the columns. This is followed by the row address from the X-address
counter and, if required, the block address.
Figure 3-3 MBIST address scrambling
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Содержание PL310
Страница 4: ...Contents iv Copyright 2007 2008 ARM Limited All rights reserved ARM DDI 0402B ...
Страница 8: ...List of Figures viii Copyright 2007 2008 ARM Limited All rights reserved ARM DDI 0402B ...
Страница 22: ...Introduction 1 8 Copyright 2007 2008 ARM Limited All rights reserved ARM DDI 0402B ...
Страница 56: ...MBIST Instruction Register 3 18 Copyright 2007 2008 ARM Limited All rights reserved ARM DDI 0402B ...