2.1.4. Data log retrieval

During a test, the ARM L210 MBIST Controller automatically logs the first detected failure. If required, you can retrieve the data log at the end of the test to generate failure statistics. Figure 2.4 and Figure 2.5 show the method of retrieving a data log.

Note

MBISTRESULT[0] is the serial data output for instructions and the data log.

After the MBISTRESULT[2] flag goes HIGH, stop the test by putting the PLL in bypass mode and driving MBISTRUN LOW as Figure 2.4 shows. To begin shifting out the data log on MBISTRESULT[0], drive MBISTDSHIFT HIGH. The MBISTRESULT[2] flag goes LOW two cycles after MBISTRUN goes LOW. Data begins shifting out on MBISTRESULT[0] two cycles after MBISTDSHIFT goes HIGH.

Figure 2.4. Start of data log retrieval

When the last data log bit shifts out, drive MBISTDSHIFT LOW as Figure 2.5 shows.

Figure 2.5. End of data log retrieval

Table 2.1 shows the format of the data log.

Table 2.1. Data log format

BitsDescription
[85:68]Address of the failing location.
[67:4]Failing data bits. These bits are set for faulty bits and cleared for passing bits.
[3:0]The data seed used in the test. See Data seed field, MBIR[19:16].

The address contained in the data log refers to the full address of the failing location as it appears on the MBISTADDR[17:0] port of the MBIST interface of the ARM L210. It always includes the doubleword select value in the least significant two bits (see Y addr and xaddr fields, MBIR[23:20] and MBIR[27:24] for more information on the doubleword select value). Contact ARM if you require more information.

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