CS8900
Not in Boundary Scan
Test Mode
TESTSEL switches low (AEN must be low)
ENTER BOUNDARY SCAN:
CS8900 resets, all digital
output pins and bi-directional
pins enter High-Z state,
and AEN becomes shift clock
AEN switches high
AEN switches low
OUTPUT CYCLE
34 cycles
AEN switches high
Selected output
goes low
INPUT CYCLE
AEN switches low
50 cycles
AEN switches high
AEN switches low
Selected input
copied out
to the
EEDataOut
pin
AEN switches high
All digital output pins and
bi-directional pins enters
High-Z state
TESTSEL switches high
EXIT BOUNDARY SCAN:
AEN becomes ISA bus
Address Enable
Figure 6.1. Boundary Scan Continuity Cycle
110
DS150PP2