Roku BrightSign Compact, Руководство по оборудованию

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BrightSign Compact
This information applies to a product under development. Its characteristics and specifications are subject to change without notice. Roku assumes no
obligation regarding future manufacturing unless otherwise agreed to in writing.
www.rokulabs.com © Roku 2008
The pinout of the DB9 on the REVB HD2000 board is as follows (NC=No Connect):
pin Description pin Description
1 NC 2 Receive data into HD2000
3 Transmit data out of
HD2000 4 Available 5V @ 500mA
5 Ground 6 NC
7 Optional TX 2
nd
channel 8 Optional RX 2
nd
channel
9 NC
DB15 Switch/LED connector
The Switch/Led connector is a DB15 Female. This connector is used to allow the Compact to control
external LEDs or other devices requiring 24mA of current or less. Connect the LED outputs to the LED
ANODE and connect LED CATHODE to ground. If you want to connect up some other device then the
output is capable of sourcing or sinking up to 24mA at 3.3V, but we do have a series resistor of 100 Ohms
in each line. This connector also allows connecting up external contact closures to ground. In order to
connect a switch, connect one side of the switch to the switch input, and connect the other side of the
switch to one of the ground pins on the DB25 connector. Finally the connector can also supply 3.3V at up
to 500mA to an external device. The 3.3V output is polyfuse protected and can source up to 500mA.
If a Brightsign is driving the inputs on another Brightsign, then you can at most drive 3 inputs from 1
output. Calculations follow showing why this is:
The GPIO outputs have 100 Ohm series resistors, the inputs have 1K pullup resistors to 3.3V, and the
input threshold on the 541 chips is 2V high, and .8V low. The high voltage is not a problem, but the low
voltage can be if there are too many inputs connected to 1 output.
Here are the calculations:
1 out driving 1 in: V=3.3*100/(100+1000)=0.3
1 out driving 2 in: V=3.3*100/(100+500)=0.55
1 out driving 3 in: V=3.3*100/(100+333.3)=0.76
1 out driving 4 in: V=3.3*100/(100+250)=0.94 (Too high, so we can only let 1 output drive 3 inputs
MAX!)