Atmel SpaceWire Router SpW-10X User Manual

Ref.:   UoD_SpW-10X_ 

 

Issue:  3.4 

  

 

Date:  11

 

 

37

 

5.2.3  Operation with 5V Powered LVDS Devices 

Since LVDS is based on a current loop it should not matter what the supply voltage is to an LVDS 
device connected to the SpW-10X router. However, there is a potential problem when connecting to 
devices with power supplies greater than 3.3 V, which is the supply voltage of the SpW-10X device. It 
should be emphasised that during normal operation there is no problem, but if the LVDS device 
connected to the SpW-10X device can fail in such a way as to put a higher voltage than 3.3 V on to 
the pins of the SpW-10X device then this can cause a problem. The simplest way to overcome this 
potential problem is to ensure that the LVDS devices driving the SpW-10X device are all powered by 
3.3V. 

5.3  EXTERNAL PORT DATA SIGNALS 

The External port signals are listed in Table 5-3. The timing of these signals is shown in Figure 6-1 
External port write timing specification and Figure 6-2 External port read timing specification.   

112 
111 
110 
107 
104 
103 
102 
101 
100 
 

Out Output data from external port number one 

FIFO.  Bit eight determines the type - data, 
EOP or EEP.  The encodings are defined as: 
 
 

(8)(7......0)

 – Bits 

 (0)(dddddddd)

 - Data byte 

 

(1)(XXXXXXX0)

 - EOP. 

 

(1)(XXXXXXX1)

 - EEP. 

 
Bit 7 is the most significant bit of the data byte. 

CMOS3V3

113 

Out FIFO ready signal for external output port 

zero. When high the FIFO has data. When low 
the FIFO is empty. 

CMOS3V3

114 

In 

Asserted (low) to read from the external output 
port zero FIFO. 
A pull-up resistor (e.g. 4k7 

Ω) should be 

connected to this input if External FIFO port 9 
is not being used. 

CMOS3V3

123 
122 
121 

In 

Input data to external port number one FIFO. 
Bit eight determines the type - data, eop or 
eep.  The encodings are defined as: 

CMOS3V3