Atmel SpW-10X Port Control/Status Registers, Generic port control/status register fields

SpW-10X	Ref.:	UoD_SpW-10X_
SpaceWire Router		UserManual
	Issue:	3.4
User Manual
	Date:	11th July 2008

WARNING

Care must be taken when setting a the routing tables to avoid a possible infinite loop. For example if there is a SpaceWire link made between two ports of a single router and a logical address routes a packet out of one of these ports then that packet will arrive back at the router, and be routed back out of the port again. Depending on the size of the packet it may block because it cannot get access to the output port the second time around as the tail of the packet is still being fed to the output port. In this case the blockage will cause a timeout (when watchdog timer mode set – see section 8.3.5) and the packet will be spilt. If the packet is a small packet it could continually circle around the loop. A SpaceWire network architecture and configuration should be checked for possible loops for all logical addresses being used. Unused logical addresses should NOT be configured in the SpW-10X routing tables so that a packet arriving at a router with an invalid (unused) logical address will be spilt immediately.

9.4 PORT CONTROL/STATUS REGISTERS

The port control/status registers address range is 0 – 31 (0x0000 0000 – 0x0000 001F )

The port control/status registers provide the means to configure and control the ports of the router and for reading the status of each port. There is a port control/status register for each SpaceWire port, each External port and for the configuration port. The address in configuration memory space of a port control/status register reflects the physical address of the port. For example, the register for port 0, the configuration port, is at address 0, and the register for a SpaceWire port number 3 is at address 3. Each port control/status register is a 32-bit register.

The fields within the port control/status register depend on the type of port that it is attached to. All port control/status registers have fields for port type and current port connection. These generic fields are described first followed by the specific fields for the configuration port, SpaceWire ports and External ports.

Port control/status register bits 31:24 are generic to all ports. Register bits 23:0 are specific to the type of port to which the register is attached.

9.4.1 Generic port control/status register fields.

The configuration port control/status fields are described in Table 9-4.

Table 9-4 Configuration Port Control/Status Register Fields

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