Hardware User Guide UG-400
Rev. 0 | Page 9 of 20
ISOLATED SPI
Two isolated SPI ports are implemented using the ADuM3401,
the ADuM3402 iCoupler signal isolators, and the ADuM5000
isoPower isolated dc-to-dc converter. The isolated SPI0 imple-
mentation on the ezLINX hardware uses the ADuM3401. The
ADuM3401 connects to SPI0 of the Blackfin ADSP-BF548 and
is used to isolate the SCLK, MISO, SSEL1, and MOSI lines. The
ADuM3402 is used for isolating the SPI slave select lines. Figure 8
shows a circuit diagram of the implementation of isolated SPI1
using the ADuM3401, ADuM3402, and ADuM5000 on the
ezLINX hardware.
The isolated SPI2 implementation on the ezLINX hardware uses
the ADuM3401. The ADuM3401 connects to SPI2 of the ADSP-
BF548 and is used to isolate the SCLK, MISO, SSEL1, and MOSI
lines. The ADuM3402 is used for isolating the SPI slave select
lines. Figure 9 shows a circuit diagram of the implementation of the
isolated SPI2 using the ADuM3401, ADuM3402, and ADuM5000
on the ezLINX hardware.
The V
DD1
pin (Pin 1) of the ADuM3401 and ADuM3402 and
the V
DD1
pins (Pin 1 and Pin 7) of the ADuM5000 are powered
by 3.3 V. T h e ADuM5000 generates an isolated 3.3 V, which is
used to supply power to the V
DD2
pin (Pin 16) of the ADuM3401
and ADuM3402.
Two 7-pin screw terminal connectors, J10 and J25, are used for easy
access to the SPISCK (Pin 1 of J10 and J25), SPIMOSI (Pin 2 of J10
and J25), SPISEL1/SPISS (Pin 3 of J10 and J25), SPIMISO (Pin 4
of J10 and J25), SPISEL2 (Pin 5 of J10 and J25), SPISEL3 (Pin 6 of
J10 and J25), and SPI_ISO_GND (Pin 7 of J10 and J25) signals.
To connect the isolated SPI0 as a master, connect Jumpers JP5,
JP7, JP9, JP11, JP13, JP15, JP21, and JP36 while leaving Jumpers
JP6, JP8, JP10, JP12, JP14, JP16, JP20, and JP37 open (see the
Warnings s
ection). To connect the isolated SPI0 as a slave, connect
Jumpers JP6, JP8, JP10, JP12, JP14, JP16, JP20, and JP37 while
leaving Jumpers JP5, JP11, JP13, JP15, JP21, and JP36 (see the
Warni ngs section).
Table 1. Isolated SPI0 Connections
Jumper SPI0 Master SPI0 Slave
JP5 Connect Open
JP6 Open Connect
JP7 Connect Open
JP8 Open Connect
JP9 Connect Open
JP10 Open Connect
JP11 Connect Open
JP12 Open Connect
JP13 Connect Open
JP14 Open Connect
JP15 Connect Open
JP20 Open Connect
JP21 Connect Open
JP36 Connect Open
JP37 Open Connect
To connect the isolated SPI2 as a master, connect Jumpers JP22,
JP24, JP26, JP28, JP30, JP32, JP35, and JP38 while leaving
Jumpers JP23, JP25, JP27, JP29, JP31, JP33, JP34, and JP39 open
(see the Warnings section). To connect the isolated SPI2 as a slave,
connect Jumpers JP23, JP25, JP27, JP29, JP31, JP33, JP34, and
JP39 while leaving Jumpers JP22, JP24, JP26, JP28, JP30, JP32,
JP35, and JP38 open (see the Warnings section).
Table 2. Isolated SPI2 Connections
Jumper SPI2 Master SPI2 Slave
JP22 Connect Open
JP23 Open Connect
JP24 Connect Open
JP25 Open Connect
JP26 Connect Open
JP27 Open Connect
JP28 Connect Open
JP29 Open Connect
JP30 Connect Open
JP31 Open Connect
JP32 Connect Open
JP33 Open Connect
JP34 Open Connect
JP35 Connect Open
JP38 Connect Open
JP39 Open Connect
The ADuM5000 contains isoPower technology that uses high
frequency switching elements to transfer power through the
transformer. Special care must be taken during PCB layout to
meet emissions standards. See the AN-0971 Application Note,
Recommendations for Control of Radiated Emissions with
isoPower Devices, for board layout recommendations.
Warnings
JP20 and JP21
JP20 and JP21 should never both be connected because doing
so will create a short circuit between 3.3 V and GND.
JP34 and JP35
JP34 and JP35 should never both be connected because doing
so will create a short circuit between 3.3 V and GND.
