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MBIST Instruction Register
3-2
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ARM DDI 0414C
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3.1
About the MBIST instruction register
The MBIST executes loaded instructions stored in the MBIR. The MBIR is 58 bits wide
and divided in a control unit part of 18 bits and a dispatch unit part of 40 bits.
The MBIR is loaded through serial port
MBISTDATAIN
of the control unit when
MBISTSHIFT
is asserted. When
MBISTSHIFT
is asserted again, the control unit
passes
MBISTDATAIN
serially to the dispatch unit through its
MBISTTX[3]
port.
Figure 3-1 shows the control unit part of the MBIR.
Figure 3-1 MBIST instruction register control unit
The control unit contains the following fields:
Pattern
Specifies the test algorithm.
Control
Specifies MBIST mode of operation and sticky or nonsticky fail
flag.
Write latency
Specifies the number of cycles to enable a RAM write.
Read latency
Specifies the number of cycles to enable a RAM read.
Figure 3-2 shows the dispatch unit part of the MBIR.
Figure 3-2 MBIST instruction register dispatch unit
The dispatch unit contains the following fields:
CPU On
Controls the data comparison for the CPUs under test.
Pattern
17
12 11
6 5
3 2
0
Control
(57)
(52) (51)
(46) (45) (43) (42) (40)
Write Latency
Read Latency
31
28 27
24 23
4 3
1 0
39
36 35
32
CPU On
ArrayEnables
2
MaxXAddr
MaxYAddr
DataWord
CacheSize
ColumnWidth