UG-277 Datasheet, PDF (10/24 Pages) Analog Devices – SDP-B Controller Board

UG-277
Pin Sharing
Two types of pin sharing occur on the SDP-B board and must
be considered when using two or more of the connector’s
peripheral interfaces between a daughter board and the SDP
board. The first type is pin sharing that occurs internally in the
Blackfin processor. The second type is pin sharing that occurs
when a single Blackfin processor output pin is shared across
both Connector A and Connector B.
Internal Blackfin processor pin sharing can restrict the
simultaneous availability of peripheral interfaces on a single
connector or across both connectors. The Blackfin processor's
internal design has multiple signals physically sharing each
single output pin. As mentioned previously, the pins on the 120-
pin connector were defined independently of this pin sharing.
This has the effect of limiting the peripherals, which can be
used simultaneously on the SDP. A system designer must
consult the ADSP-BF52x Blackfin Processor Hardware
Reference for the ADSP-BF527 processor to ensure the selected
peripherals are available simultaneously and their signals do not
share Blackfin processor output pins. An example of this
sharing is that the SPORT and PPI peripherals physically share
the same Blackfin processor pins. Therefore, these two
interfaces cannot be utilized in a single application. Pin sharing
also occurs from certain Blackfin processor output pins to both
Connector A and Connector B. The following signals are
connected from a single Blackfin processor output pin to both
Connector A and Connector B:
• I²C Bus 1, Pin 41 and Pin 42
• SCL 0 on I²C Bus 0, Pin 79
• GPIO 6 and GPIO 7, Pin 47 and Pin 67
• Timer D, Pin 72
• UART, Pin 59 and Pin 62
SDP User Guide
POWER
The SDP-B board requires that any daughter board connected
to the SDP-B board provides the SDP-B board with 5 V at 200
mA. This supply should be made available on Pin 1 (VIN) of
the 120-pin connector. This supply is required to power the
Blackfin processor, the memory, and the other components on
the SDP-B board. The SDP board also provides 3.3 V at 20 mA
on Pin 116 (VIO_3.3) to connected daughter boards as the VIO
voltage for the daughter board. Pin 5 (USB_VBUS) is connected
to the +5 V line of the USB connector, providing 5 V ±10% as
an output of the SDP board.
DAUGHTER BOARD DESIGN GUIDELINES
The daughter board design guidelines specify the layout,
connector position, keep out areas, and dimensions of potential
daughter boards. This guidance is to ensure that a daughter
board can connect off either Connector A or Connector B of
the SDP-B board. Following these guidelines ensures that both
connectors on the SDP can have any one of the catalogue of
daughter boards physically attached to the connectors
simultaneously.
Connector Location
The daughter board connector and securing screw holes are to
be located in the top left hand corner. This arrangement can
be seen for Daughter Board A in Figure 4. Note that Daughter
Board B is the same as Daughter Board A rotated clockwise
through 90°. The exact location of the connector from the
board's edge is important in order to allow both boards connect
at the same time. As seen in Figure 4, if either board exceeds
these dimensions, it is not possible to connect the other. Every
effort was made to extend the 5.9 mm dimension as large as
possible in order to allow space for vias between the connector
and the edge of the board. These are absolute maximum
dimensions and should not be exceeded.
Rev. B | Page 10 of 24