12. Register Descriptions
350
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
12.5.60
Semaphore 0 Register
When a SEMx is 0, this semaphore can be obtained by writing a 1 to the SEMx bit with a unique tag
TAGx. If on a subsequent read, the SEMx bit is set and the TAGx field contains the same unique tag,
then the semaphore has been obtained successfully.
To release a semaphore, write a 0 to the SEMx bit and the same tag that was used to obtain the
semaphore. If the tag is different from the tag that is in the register, then the write will have no effect.
Access to a single semaphore in this register requires a byte-wide transaction.
Register Name: SEMA0
Register Offset: 0x470
PCI
Bits
Function
PB
Bits
31-24
SEM3
TAG3
0-7
23-16
SEM2
TAG2
8-15
15-08
SEM1
TAG1
16-23
07-00
SEM0
TAG0
24-31
Name
Type
Reset
By
Reset
State
Function
SEM3
R/W
G_RST
0
Semaphore 3
TAG3[6:0]
R/W
G_RST
0
Tag 3
SEM2
R/W
G_RST
0
Semaphore 2
TAG2[6:0]
R/W
G_RST
0
Tag 2
SEM1
R/W
G_RST
0
Semaphore 1
TAG1[6:0]
R/W
G_RST
0
Tag 1
SEM0
R/W
G_RST
0
Semaphore 0
TAG0[6:0]
R/W
G_RST
0
Tag 0