Display
Features
Only monochrome text is available in genlock/overlay mode. Characters from ROM are displayed by
default in white with a thin black outline. Halftone (reduced video intensity) and black character
backgrounds are optional. Characters from font RAM have less display flexibility. This includes
European language support, which is part of the default RAM character set. Color display features,
including character background control, are supported in local video generation mode. In local mode,
blue matte background is supplied by default. Other background colors are available by command.
Blinking may be selected for any character or group in either video mode. Manual adjustment of
transparency as well as character and background brightness (gray scale) is optional, with external
circuits. Vertical scrolling may be configured for any contiguous group of display rows. A single crawl
(horizontal scroll) line can display up to 256 characters sequentially. No other display is possible
when crawl mode is invoked. The entire text display may be toggled on or off without affecting the
contents of display RAM. Writing to display RAM is permitted with display on or off. A non-volatile
boot script memory stores up to 512 characters that may be used to configure BOB-3 and/or
automatically generate a display at power-up time.
Note: Product specifications, policies and prices are subject to change without notice. Contact Decade Engineering
to confirm current status if any specified parameter is critical to your application.
System Hookup
Basic Hookup:
The schematic diagram below shows a typical BOB-3 installation. The serial data rate defaults to 9600bps. 4.7K
pullup resistors (to pin 3) are required at pins 12, 13, and 14 unless those three socket contacts are left floating. An
RS-232 hardware interface is required for connection to a PC COM port (see next section), but not for connection
to a microcontroller. Some optional BOB-3 features are not implemented here, but are discussed in other parts of
this document.
VIDEO OUT
BOB-3
30-PIN SIMM SOCKET
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
DATA IN
VIDEO IN
DATA OUT
GND
+12V
4.7K x 3
Important Notes:
Pin 2 and pin 29 must be linked through a PCB ground plane or other low-impedance connection. Use 22AWG or
larger wire (or multiple wires) for hand-wired installations or development fixtures.
April 22, 2004: Decade Engineering now recommends that new BOB-3 applications use regulated 5VDC power at
pin 3 instead of unregulated DC applied to pin 1 as shown above (also see pin description table). There will be no
difference in BOB-3 operation, aside from reduced on-board power dissipation. This hookup change simply makes
your host circuit board compatible with power supply requirements for BOB-4, our as yet ‘unannounced’ next-
generation video overlay module. No further BOB-4 information is published at this time, but we will attempt to
answer specific questions from customers regarding support for existing BOB-3 features in BOB-4.
BOB-3 Version 3.4 Application Guide ~ Copyright © 2004 by Decade Engineering ~ Page 3
