BeagleBoardRawLCD

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This page is about interfacing BeagleBoard to Raw LCD Panels. The BeagleBoard can drive raw LCD panels through its DVI port by interfacing through an external LCD driver board. The Digital View ALR-1400 [1] is one such driver board. Several individuals have been interested in having the LCD signals routed out to the expansion connector--without a board change by TI this is one way to address this perceived short-coming. Below documents connecting of the BeagleBoard through an ALR-1400 to drive a WVGA (800x480) LCD panel [2] OSD070TN84.

Lcd splash.jpg

The following was needed to implement this setup:

  • (1) LCD Panel OSD070TN84
  • (1) HDMI to DVI-D cable
  • (1) Belden SMT to through-hole adapter PCB (0.5mm pitch) [3]
  • (1) 40 Pin 0.5 mm top entry FPC connector
  • (1) 40 Pin 0.5 mm length of FPC flat cable
  • (1) Digital View ALR-1400
  • (1) Digital View 762-426500500-3 TTL cable
  • (1) 4 Pin 2.5 mm JST Connector Housing (Tap Aux. 5V line for LCD Backlight)
  • (2) Crimp Terminals for JST 2.5 mm Housing
  • (1) Molex 2 Position 3mm Single row connector housing (ALR-1400 Power)
  • (2) Crimp Terminals for Molex 3mm connector housing (ALR-1400 Power)
  • (optional) Digital View control panel (includes power switch and 5 push buttons for OSD control)
  • (not optional) lots of patience

Let me start by saying that if you want to do this and have the flexibility use one of the suggested panels from Digital View's documentation, you should do it. The reasons for this are two-fold: (1) The LCD interface connectors on the ALR-1400 are very high density Hirose and the proper crimp tools to terminate them run anywhere from $500-$1200 USD. (2) There is no guarantee that a panel not on Digital View's list of supported LCD's will work. I tried a couple of different panels for this project and only this one works as-is.

Also, if something is done wrong, you can easily ruin a very expensive LCD panel. Proceed at your own risk.

Very carefully mount the FPC connector to the Beldyn adapter board. Use lots of flux and be very patient. It takes only the smallest amount of solder to wet the contacts. I've done this several times now, and it still takes me at least 45 minutes to solder a 40 pin connector.

Next, leaving enough wire length, cut the Digital View TTL cable (yeah, I know it was nearly $40 from mouser electronics, but it's cheaper than a $1,000 crimp tool). Strip back the outer insulation and the EMI shield. I went ahead and re-shrink wrapped mine.

I used the following table to translate between the Digital View Cable and the FPC interface board (please check for accuracy and/or revisions):

Beldyn adapter.jpg

ALR Pin Number Pin Function LCD Pin Number
1 gnd 40
2 gnd
3
4
5
6
7 r0 35
8 r1 34
9 r2 33
10 r3 31
11 r4 30
12 r5 29
13 gnd 28
14 gnd 36
15
16
17
18
19 g0 27
20 g1 26
21 g2 25
22 g3 23
23 g4 22
24 g5 21
25 gnd
26 gnd 20
27
28
29
30
31 b0 19
32 b1 18
33 b2 17
34 b3 15
35 b4 14
36 b5 13
37 gnd 12
38 gnd 16
39 vsync 10
40 dclk 37
41 hsync 11
42 de 9
43
44 vcc 6
45 vcc 7
46 vcc 8
47
48
49
50

Next, Connect a 5 volt line to the LED Backlight (Pin 4 on JST connector CNA1 on ALR-1400) to pin 1 of the Beldyn board and Backlight ground to pin 4 of the Beldyn board to JST connector CNA1 pin 3. The Backlight brightness control is on Beldyn pin number 3. It is a PWM input, I tied it to LCD VCC for full brightness.

Make a power cable for the ALR-1400 using the above Molex connector.

I already had a Digital View front panel from another project and used it at first. This is not a requirment. If you do not have one or want to purchase one, you can simply install a jumper at JP6. Additionally, the Digital View documentation explains how to control the ALR-1400 through a serial interface.

I found that I had to adjust many of the settings for proper color correction through the front panel. So you may want to investigate the methods of adjusting the settings at this time.

The switch settings that seem to work well with this LCD are: SW1 (8 position DIP switch) On-Off-Off-On-Off-On-On-Off and SW2 (2 Position DIP Switch) On-On.

Please note there may be additional instructions on initial set-up of the ALR-1400. Please consult the Digital View documentation accordingly.

Connect 12 Volts to the ALR-1400 without the LCD connected and check that proper voltages are where they should be. My panel/ALR-1400 combination draws about 0.5 amps at 12 volts.

If everything checks out, power the unit back down, connect the LCD, and power it back up. If you've connected your BeagleBoard, you should see the splash screen.