Bist Sequence System Test With External Loopback Modes - Motorola MC92603 Reference Manual

6.2.2 BIST Sequence System Test with External Loopback
Modes
The MC92603's transmitter has an integrated, 23rd order, pseudo-noise (PN) pattern
generator. Stimulus from this generator may be used for system testing. The receiver, has a
23rd order signature analyzer that is synchronized to the incoming PN stream and may be
used to count code group mismatch errors relative to the internal PN reference pattern.
This implementation of the 23-bit PN generator and analyzer uses the following
polynomial:
5
f = 1 + x
The total mismatch error count is reset to zero on entering BIST mode. The count is updated
continuously while in BIST mode. The value of the count is presented on the receiver
interface signals, RECV_x_7–RECV_x_0, which make up the 8-bit error count. The value
of the count is sticky in that the count will not wrap to zero on overflow, but rather, stays at
the maximum count value (11111111).
An error counter is maintained in MDIO RA 18 for each
specific channel in all BIST test modes. See Chapter 4,
"Management Interface (MDIO)," for details.
The RECV_x_ERR, RECV_x_DV, and RECV_x_COMMA signals, as interpreted and
shown in Table 6-5, have special meaning in this test mode. They report the status of the
receiver and PN analysis logic.
RECV_x_ERR RECV_x_DV
Low Low
Low High
Low High
High Low
High High
The BIST sequence makes use of the 8B/10B encoder/decoder. Therefore, this test mode
overrides the setting on the TBIE signal and forces byte interface mode. Additionally, the
BIST sequence requires that a normal byte alignment mode be used. The setting of BSYNC
is overridden, forcing the device into the byte aligned mode, which forces BSYNC high
internally.
MOTOROLA
23
+ x
Table 6-5. BIST Error Codes
RECV_x_COMMA
Don't care
Low
High
Don't care
Don't care
Chapter 6. Test Features
NOTE
Description
Not byte/word sync. The receiver is in start-up or has lost byte
alignment and is searching for alignment.
BIST running. No PN mismatch this code group.
BIST running. This code group is a COMMA code group.
Receiver byte/word synchronized. PN analyzer is not locked.
BIST running. PN mismatch error for this code group.
System Accessible Test Modes
6-5