Cortex-A8 R2P2.pdf - ARM Information Center

Design for TestArrayFail[22:0] fail_addr[16:2] failing_bits[37:0]pattern[5:0]expect_data[3:0]alg_pass[3:0]Figure 11-5 L1 MBIST Datalog Register bit assignmentsArrayFail[22:0]Read the ArrayFail[22:0] field to identify arrays that produce failures. The bits in thisfield correspond to the bits in the L1_array_sel[22:0] field in the L1 MBIST InstructionRegister. Table 11-5 on page 11-7 shows how each bit corresponds to one of the L1arrays. Testing more than one array while not in bitmap test mode can set more than oneArrayFail[22:0] bit to 1. The least-significant 1 in the ArrayFail[22:0] field indicates thefirst failing array.expect_data[3:0]Read the expect_data[3:0] field for the expected data seed for the first failing array.Because data seed toggling occurs throughout pattern execution, the value in this fielddoes not always correspond to the programmed data seed.fail_addr[16:2]Read the fail_addr[16:2] field for the physical address of the first failing array. See theaddress scramble information contained within the Design for Test implementationdocumentation for details on shows how this address is constructed.failing_bits[37:0]Read the failing_bits[37:0] field to identify failing bits in the first array that fails. Thisfield contains the EXCLUSIVE-OR of read data and expect data.alg_pass[3:0]For the first failing array, read the alg_pass[3:0] field to identify which pass of thealgorithm produced a failure. For example, the CKBD algorithm has four passes, wscan,rscan, wscan, and rscan, numbered 1, 2, 3, and 4. Because failures only occur on reads,a CKBD failure results in an alg_pass[3:0] value of b0010 or b0100.pattern[5:0]Read the pattern[5:0] field to identify the pattern running at the time of the first failure.Table 11-2 on page 11-4 shows the pattern codes. This field is useful when runningmore than one pattern during a GO-NOGO test.ARM DDI 0344E Copyright © 2006-2008 ARM Limited. All rights reserved. 11-15