CT2577 Datasheet, PDF (20/41 Pages) Aeroflex Circuit Technology – APPLICATION NOTE 108

b) The self test data word is read from the appropriate RAM location, transferred to the encoder
and transmitted contiguously following the command word.
c) The Command word is received by the Manchester decoder, if valid and with correct RT
address or broadcast is stored in the RT protocol.
d) The data word is received by the decoder and if valid is stored in the 32 word data memory.
e) The RT protocol will validate the message and if successful will write the Command word to
the 32 word Command / Status memory and transfer the data word to the appropriate RAM
location.
5. As the data word received is written to the same RAM location that it was originally accessed
from, the contents should be altered while the self test is in progress (eg. write 0000). This can be
done immediately after the BC to RT transfer was initiated. There is approx 45 us for the self test
to complete.
6. To ensure that the RAM contents have been altered it is advisable to read the data back from the
RAM.
7. On completion of a successful self test the signal NCMDSTRB will go active low, after which the
data can be read from the RAM and compared with the data used in the self test.
8. In addition the Command word used in the self test may be read from 0 00 00.
9. Disable self test by writing to 1 00 08. The device will revert back to its original state (BC or RT).
APPLICATION NOTE #108
20
Released 9/98