80KSBR200 Datasheet, PDF (34/172 Pages) Integrated Device Technology – sRIO SERIAL BUFFER FLOW-CONTROL DEVICE

IDT 80KSBR200
Notes
Advanced Datasheet*
sRIO 8/16 Bit Destination IDs for sRIO Doorbells
While typically all transactions with the SerB will be either 8 or 16-bit addresses exclusively, the SerB may be used in
systems that mix 8 and 16 bits. Every flag register contains 16 bits that may be used as a destination ID. To define the
usage of 8 or 16 bits, every flag register that is capable of sending a doorbell contains a "TT" designation in the flag
register that indicates whether the full 16 bits should be used as a destination ID for the doorbell or only the 8 LSBs. The
sRIO packet will be formed with the address, based upon the TT bit.
In no case will a transaction contain an 8-bit source ID and a 16-bit destination ID (or the reverse) in the same doorbell.
This does not exclude the possibility of a queue using 8 bits as the destination ID for the queue, and then generating a
doorbell to a 16-bit destination. It does mean that if a user is trying to mix 8 and 16 bit destination IDs, they will need to
correlate the 8 LSBs for both.
sRIO Flag Doorbell Payload
The sRIO Flag Doorbell Payload is a maximum of 16 bits. The payload consists of the following
◆ _{2 bits = Unused}
◆ _{6 bits = Register number of the flag that is causing the doorbell}
◆ _{8 bits = Register contents showing the status of every flag in the register, regardless of whether the flags are}
masked.
5.2 External Interrupt Pins Int(0) and Int(1)
Each of the two external interrupt pins may be toggled by any unmasked flag. Each pin has its own flag mask available
allowing the user to designate the flag or combination of flags that will cause the interrupt pin to toggle.
There are two types of flags indicated in the flag register, which are RT (Real Time) and CL (Clearable) flags. When an
unmasked RT flag toggles an interrupt pin, the pin will remain active as long as the flag is active and cannot be clear,
except by reprogramming the mask. When an unmasked CL flag toggles the pin, the user may reset the flag, and the inter-
rupt indication will be removed from the pin until the flag again toggles or the mask is reprogrammed.
It is expected that one of the two pins will be programmed to indicate a generic flag concern, including all flags that may
cause concern to the user. The second flag pin would be used to monitor an immediate or frequently used condition, such
as "packet ready", meaning that the toggling of the flag generates immediate response without further determination
concerning the cause of the interrupt.
There is no ability for sRIO to toggle one of the interrupt pins directly through a command. sRIO may toggle a pin indi-
rectly by creating a condition that causes one of the unmasked flags to toggle, subsequently affecting the designated pin.
5.2.1 Clearing Interrupt
Clearing an interrupt is accomplished by clearing all flags that are causing the interrupt. Since multiple flags are
together in a register and additional flags may toggle after a register has been read, completely clearing a register may
clear unrecognized flags. The proper usage of flags and how to clear them, is described in section 8.5, Flag and Flag Mask
Registers in the notes of this datasheet. As described, writing a "1b" to a flag clears it. Writing a "0b" to a flag does not
affect the flag. This way, any flag may be individually cleared or cleared in combination with other flags in the same
register.
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March 19, 2007
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