A complete MIDI interface will be on the main board.
As I understand it, the LCD display microcontroller monitors the
MIDI data stream looking for a SYSEX string.
My thought was to simply send the 5 volt level TXD pin to the external LCD board.
Not the current loop signal.
That would eliminate any need for level shifting or an opto isolator on the display sub
assembly.
It would also allow the display to mounted in many more mechanical positions if seperate
from the main board, and with it's own power supply.
It would also be possible to have different size displays, or multiple displays each with a
unique SYSEX code.
That seems like the easiest solution. Rough in a connector for a smart display in the main
board, then the display sub-assembly can change and evolve as needed.
--- In ComputerVoltageSources@yahoogroups.com, "djbrow54" <davebr@...> wrote:
>
> --- In ComputerVoltageSources@yahoogroups.com
> > Backlight is 160 mA. Sounds like the 4 pin interface means the LCD
> > microcontroller is on another board.
>
> The backlights for these LCD controllers do take a lot of power. My
> first display was a VFD which took 400 mA of +5!!! My 8x2 takes about
> 70 mA of +5. I would suspect that we wouldn't use this display at
> full 160 mA backlight. Generally, they are very bright! Some
> experimentation would be needed to determine an appropriate
> brightness. The A and K for the backlight are on separate pins which
> means we could power these from either a +5 or a +15 supply if
> desired.
>
> The LCD logic is only a couple of mA. The controller is the same.
> The MIDI spec is 5 mA. Total display/MIDI power without the backlight
> is probably around 10 mA. I think you will find, however, that the
> AtomPro28 might consume more than 25 mA. My PSIM consumes 70 mA with
> all the LEDs on. I've not measured it with the LEDs off.
>
> > > Doing a little research, I found the following Lumex LCD.
> > > LCM-S01602DSF/C
> > > LCD 16x2 STN Y/G LED backlit
> > > $13.36 available from stock from either Mouser or Digi-Key
> > > Board size: 3.346 x 1.181 inches
>
> This looks like a nice display. Crummy data sheets, though. I assume
> the Samsung controller is compatible with the Hitachi. There are some
> features built into the controller that it would be nice to know if
> are implemented in the display module. For example, what is the
> character font (I can't find it), how many programmable characters,
> etc. I assume this is a 5x7 with an 8th row for cursor. I'll keep
> looking for a complete data sheet.
>
> Dave
>