Atmel SpW-10X user manual Status Interface Operation, SpaceWire Router, User Manual, Preliminary

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

SEL_EXT_TIME signal when EXT_TICK_IN signal has a rising edge. If SEL_EXT_TIME is 1 then the EXT_TIME_IN(7:0) inputs are used to provide the contents of the time-code. If SEL_EXT_TIME is 0 then the internal time-code counter provides the least-significant 6-bits of the time-code and the EXT_TIME_IN(7:6) inputs provide the most-significant 2-bits. When using the EXT_TIME_IN(7:0) inputs to provide the complete time-code, the time-code is only broadcast if it is a valid time-code i.e. if the count in bits 5:0 is one more than the internal time register of the router (see SpaceWire standard [AD1]). Note that only one router or node in a SpaceWire network should normally operate as a time master generating time codes (see SpaceWire standard [AD1]).

EXT_TICK_OUT

EXT_TIME_OUT

Figure 6-4 Time-Code Output Interface

When a valid time-code is received by the router the value of this time-code (flags plus time value) will be placed on the EXT_TIME_OUT outputs and the EXT_TICK_OUT signal will be set to zero. The EXT_TICK_OUT signal is set to one a short time later, once the EXT_TIME_OUT outputs have stabilised, to indicate that these outputs are valid. They then remain valid until the next time-code is received and the EXT_TICK_OUT signal will be set to zero.

TIME_CTR_RST

TIME_CTR Count

Figure 6-5 Time-code reset interface

When a rising edge is detected on TIME_CTR_RST then the time-code register is reset to zero.

6.3 STATUS INTERFACE OPERATION

The STAT_MUX_ADDR signal determines the output status on STAT_MUX_OUT as shown in Figure 6-6 and in Table 6-1.

CLK

STAT_MUX_ADDR

STAT_MUX_OUT

Figure 6-6 Status Multiplexer output interface

When STAT_MUX_ADDR is stable STAT_MUX_OUT is output from after each clock edge.

Preliminary 49