I needed an LCD for a project I am doing and because my local electronics store was already closed I decided to look around my house. I found my old PalmPilot and lucky for me, there is software for it called PalmORb that emulates a Matix Orbital LK204-25.
Using my PC and LCDsmartie I was able to get the LCD to work at 9600 baud over serial quite easily.
However, using this tutorial
and this pinout
does nothing. The LCD just sits there.
Any idea on why this might be happening?
I should note that I am using an external power supply for the palm.
Right now I can get it to display all of
Instead of "Hello World"
The serial options has a few settings, but I don't know which ones are the right ones.
Baud Rate: 19200
Data Bits: 5|6|7|8
Stop Bits: 1|2
Flow Control: Hardware|None
Use larger input buffer
The baud rate is set to 19200 in the code, so I know that is right.
Any tips on things I should try?
It looks to me like the arduino example you reference uses the "rs232ttl" input of the display, while the Palm almost certainly has only "TRUE" rs232.
Note: the code below is for a non-inverted TTL serial signal. Some displays, like the one pictured above, have a jumper (J6 in this case) that you have to set in order for this to work.
You'll need some sort of ttl to rs232 conversion. If you're lucky, this could be a simple inverter.
I've been trying to get a Palm compatible Visor in a serial cradle to work as a Matrix Orbital display. It works with LCDsmartie, and the Arduino is outputing serial to the monitor program satisfactorily via an STK500 board, although the combination doesn't work - just as you've found.
One clue is researching the distinction between DCE and DTE RS232 devices. The computer is a DTE and the PDA (emulating the Matrix Orbital) is a DCE - which is why it works. I had (originally) expected the Arduino/STK500 to be a DTE, but it's not - it's a DCE, which explains how it can communicate without a null modem to the computer. I put the null modem in the chain, expecting the PDA to now work, but it didn't. So there's more going on here, perhaps some missing handshaking on the lines. Or the fact that STK500 is not putting out full +12v/-12v RS232 signals like the PC port (it's closer to +5v/-5v) - that's my current hypothesis.
It's not really cost effective to research much further, like you, it was intended to be a stop-gap display, I'll have a real display on hand shortly, but I am curious - it should work.