M67025E
Table 5. Example Semaphore Procurement Sequence
Function
D0 - D15 Left
D0 - D15 Right
Status
No Action
1
0
1
1
Semaphore free
Left Port Writes ’0’ to Semaphore
Left Port has semaphore token
No change. Right side has no write
access to semaphore
Right Port Writes ’0’ to Semaphore
Left Port Writes ’1’ to Semaphore
Left Port Writes ’0’ to Semaphore
0
1
1
1
0
0
Right port obtains semaphore token
No change. Left port has no write
access to semaphore
Right Port Writes ’1’ to Semaphore
Left Port Writes ’1’ to Semaphore
Right Port Writes ’0’ to Semaphore
Right Port Writes ’1’ to Semaphore
Left Port Writes ’0’ to Semaphore
Left Port Writes ’1’ to Semaphore
0
1
1
1
0
1
1
1
0
1
1
1
Left port obtains semaphore token
Semaphore free
Right port has semaphore token
Semaphore free
Left Port has semaphore token
Semaphore free
Note:
1. This table denotes a sequence of events for only one of the 8 semaphores on the M67025E.
Figure 1. Semaphore Logic
10
4146J–AERO–06/03
ATMEL [ ATMEL ]
