Atmel AT7910E Manual de usuario descargar pdf (Pagina 5)

AT7910E [DATASHEET]

7796G AERO 02/13

The AT7910E provides a routing capability between eight SpaceWire links according to the SpaceWire Standard ECSS-

E-50-12A. In addition for use as a node interface, the AT7910E integrates other interfaces such as:

External ports

Configuration port

Time-code interface

Control/Status interface

1.1 SpaceWire Ports

The SpaceWire router has eight bi-directional SpaceWire links each compliant with the SpaceWire standard ECSS-E-50-

12A.

Each SpaceWire link is controlled by an associated link register and routing control logic. Packets received on SpaceWire

links are routed by the routing control logic to the configuration port, other SpaceWire link ports or the external FIFO ports

depending on the packet address.

Packets with invalid addresses are discarded by the SpaceWire router. The SpaceWire link status is recorded in the

associated link register and error status is held by the router until cleared by a configuration command.

1.2 External Ports

The SpaceWire router has two bi-directional parallel FIFO interfaces that can be used to connect the router to an external

host system. The external port FIFO is two data characters deep.

Each FIFO is written to or read from synchronously with the 30MHz system clock.

An eight-bit data interface and an extra control bit for end of packet markers are provided by each external port FIFO.

Packets received by the external port are routed by the routing control logic to the configuration port, SpaceWire link ports

or the other external port depending on the packet address.

Packets with invalid addresses are discarded by the SpaceWire router.

1.3 Configuration Port

The SpaceWire router has one configuration port which performs read and write operations to internal router registers.

Packets are routed to the configuration port when a packet with a leading address byte equal to zero is received. The

Remote Memory Access Protocol (RMAP) is used to access the configuration port.

If an invalid command packet is received then the error is flagged to an associated status register and the packet is

discarded.

1.4 Routing table

The SpaceWire router routing table is set by the router command packets to assign logical addresses to physical

destination ports on the router.

A group of destination ports can be set, in each routing table location, to enable group adaptive routing. When a packet is

received with a logical address the routing table is checked by the routing control logic and the packet is routed to the

destination port when the port is ready. Routing table locations are set to invalid at power on or at reset.

The routing table logical addresses can also be set to support high priority and header deletion. High priority packets are

routed before low priority packets and header deletion of logical addresses can be used to support regional logical

addressing.

An invalid routing address will cause the packet to be spilled by the control logic.

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Atmel AT7910E Manual de usuario Pagina 5