Spw-10x spacewire router – Atmel SpaceWire Router SpW-10X User Manual
Page 37
Ref.: UoD_SpW-10X_
UserManual
Issue: 3.4
SpW-10X
SpaceWire Router
User Manual
Date: 11
th
July 2008
Preliminary
37
5.2.3 Operation with 5V Powered LVDS Devices
WARNING
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.
Table 5-3 External Port Interface Signals
PinNo Signal
Dir Description
Type
112
111
110
107
104
103
102
101
100
EXT9_OUT_DATA(8)
EXT9_OUT_DATA (7)
EXT9_OUT_DATA(6)
EXT9_OUT_DATA(5)
EXT9_OUT_DATA(4)
EXT9_OUT_DATA(3)
EXT9_OUT_DATA(2)
EXT9_OUT_DATA(1)
EXT9_OUT_DATA(0)
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
EXT9_OUT_EMPTY_N
Out FIFO ready signal for external output port
zero. When high the FIFO has data. When low
the FIFO is empty.
CMOS3V3
114
EXT9_OUT_READ_N
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
EXT9_IN_DATA(8)
EXT9_IN_DATA(7)
EXT9_IN_DATA(6)
In
Input data to external port number one FIFO.
Bit eight determines the type - data, eop or
eep. The encodings are defined as:
CMOS3V3