When CUBIC is turned on or reset, it performs a series of self-tests and memory checks. During these self-tests, we will present a special self-test telemetry format to the SAC-B \ Housekeeping Serial Channel 00 and to our bilevel port. This self-test telemetry format provides feedback on the self-test status.
The Bilevel Port (BL1) will be used to indicate the status of the self-test code. The five most significant bits (at the checkout station or MOCC), which are controlled by software, will be cycled to indicate which test is being executed at any moment, according to Table 19.
Table 19: CUBIC Self-Test status (BL1)
For this test, the bits of BL1 are therefore reassigned as shown in Table 20.
Table 20: CUBIC BL1 Self-Test Bit Assignments
(Note that the test number being executed will be written into the 5 low bits of BL1 because of the bit-swap in the C&DH wiring.) Because the memory tests occur asynchronously with the telemetry sampling, the sequence of BL1 values that actually appears in the telemetry is unpredictable (some test numbers may be skipped if the test requires less time than a minor frame). If the software hangs up during the memory tests, BL1 will indicate the last test being executed. If the memory tests complete successfully, BL1 will be set to 0xF9 (at the checkout station/MOCC) for at least two minor frames before the regular housekeeping loop starts updating BL1 with its normal bit assignments given in Table 17.
During the self-tests, the HK data in words 49, 50, and 51 will be 0xFF. When the self-tests are complete, a summary block of data will be written to the Serial HK FIFO containing the results of the tests. This data will appear in the major frame following the test completion and will therefore not be correlated with the tests codes written into BL1. In minor frames 0 -- 3 of this summary block, word 49 gives the test number and words 50 and 51 give a 16 bit count of the number of errors detected (MSB in word 50, LSB in word 51). The major frame format used for the self-test summary block is shown in Table 21.
Table 21: CUBIC Self-Test Major Frame format
Here ECn is the number of defective memory words found in test n. This pattern will be used in the CUBIC Aliveness Test to verify that the instrument is functioning correctly.
If errors are found in the memory tests, the bad addresses will be stored in ICP RAM and written into the Science Data RAM using a special format (see § 4.6.7). These can be dumped to the ground using a Science Data Dump. If an error is found in the ICP RAM test, an abbreviated summary block containing only the first test result is written to the HK FIFO in case the startup code cannot progress any further.