UG-277 datasheet(10/24 Pages) AD

10 / 24 page

UG-277

SDP User Guide

Rev. B | Page 10 of 24

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

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.

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