Anyone have experience with the nice LCD alphanumeric panel driver, kit 117 from Peter Anderson and others?
I've used them happily for LCD panels without a backlight.
In another thread, a new user is having trouble with the "Set backlight brightness" commands.
He can send "Hello World"
He can send "?f" (to clear the screen)
When he sends "?BEF" to set the brightness quite high, his panel acts as if he's sending characters.
Ideas? (Panel is usually dark, but was once, briefly, bright.)
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It may be that the controller is "missing" some of the circuitry needed to control the LCD's backlight's brightness.
In the following notes, in the last of them, some external circuitry is shown....
But those notes are for one of the 117's predecessors. If your controller came with an unexplained "extra" TIP-41 transistor, or if you can't see one as part of your 117, I would guess that the transistor driver for the brightness control is still an "off-board" optional extra, to be hooked up as shown in the diagram cited above. Anyone buy a 117 recently and get backlight control working? Is my guess right?
If all of the above is right... and you have an LCD panel with backlight, you might decide just to "hardwire" the input to the brightness control, rather than mess with having it controllable from the 117... but that does seem a pity! The minor work of connecting up the transistor would seem worth it to me, to have "backlight on/off" accessible through software in the program driving the controller. Hardwire to "on" to check it is working, maybe?
I THINK... but anything you try is ON YOUR HEAD... I don't know what panel you have, etc, etc, that to hardwire the backlight "on", you connect....
From 5v, through a 4.7 ohm (yes, very small... worries me... I'd try to look at my panel's datasheet, and I'd try a bigger resistor first) resister (in series), to pin 15 of the LCD panel (Again, check YOUR panel's datasheet... you want backlight anode), and from your panel's backlight LED cathode (pin 16 on the one in the Anderson diagram) to ground.
For others reading the thread:
a) The contol language is case sensitive... "?bef" would not work.
b) The "brightness" command consists of a B followed by two characters from 0-9, A-F... i.e. they are a number, written in hex.