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4.5 Timing Characteristics SpaceWire Interface

Notes:

1. The SPW_CLK frequency must be less than 4x the SYS_CLK frequency. For example, if SPW_CLK is running at 200MHz, the SYS_CLK frequency must be

greater than 50MHz.

2. All outputs are measured using the load conditions shown in Figure 15.

3. Applies to both high pulse and low pulse.

4. A unit interval (UI) is defined as the nominal, or ideal, bit width.

Figure 8. SpaceWire Transmit Timing Diagram

Figure 9. SpaceWire Receive Timing Diagram

Symbol

Description

Min

Max

Units

SPW_CLK period

5

--

ns

(SPW_TXD[3:0])

37

ns

(SPW_TXS[3:0])

37

ns

Transmit data and strobe bit width variation

(SPW_TXD[3:0] and SPW_TXS[3:0])

UI+600

ps

Receive data and strobe bit width

(SPW_RXD[3:0] and SPW_RXS[3:0])

2.5

--

ns

t16

Receive data and strobe edge separation

(SPW_RXD[3:0] and SPW_RXS[3:0])

2.5

--

ns

t13

t13

t14

t14

t12

t12

t14

t14

t11

t11

SPW_CLK

SPW_TXD

SPW_TXS

t15

t

t16

t16

t15

t

SPW_RXD

SPW_RXS