DIG-OLE large LCD display

W

whiteoaks7

New Member
I've just had delivery of my nice new display but I must be missing something or else it's dead. To try it out I connected it to my desktop and fed it with characters "CL" at 9600,N,8,1 over the comm port. This should have cleared the screen and it didn;t. The thing boots up, running through its splash screen and confirming UART baud 9600 then nothing else happens. So should there be a cursor blinking? Should "CL" as an ascii string clear the display? I tried other codes and also got no response. I checked the data was getting to the board with a scope and it seemed fine. Is it DOA or have i missed something?

http://rover.ebay.com/rover/0/e11050.m43.l1123/7?euid=f72fa120f0264e42917717d4909a9765&loc=http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=251180493188&ssPageName=ADME:X:AAQ:US:1123

Dave
 
N

nick12ab

Senior Member
As it's designed for use with Arduino, the serial polarity will be T9600. Use an inverter IC to correct the polarity of the signals from the computer.

Also are the jumpers on the back correctly set for UART serial operation?
 
JimPerry

JimPerry

Senior Member
whiteoaks7 said:
The thing boots up, running through its splash screen and confirming UART baud 9600 then nothing else happens. So should there be a cursor blinking? Should "CL" as an ascii string clear the display? I tried other codes and also got no response. I checked the data was getting to the board with a scope and it seemed fine. Is it DOA or have i missed something?

http://rover.ebay.com/rover/0/e11050.m43.l1123/7?euid=f72fa120f0264e42917717d4909a9765&loc=http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=251180493188&ssPageName=ADME:X:AAQ:US:1123

Dave
Click to expand...
Obviously not DOA - with splash screen etc - check jumpers and comms protocol :rolleyes:
 
B

BeanieBots

Moderator
Have you set the contrast to a value that will show something? This has caught many out in the past.

EDIT:
Doh! you have already seen the splash so not that.
As said, check baud polarity/jumpers.
 
G

g6ejd

Senior Member
I've got one of these, their great value and good quality. Using a PICAXE this is how I say Hello World:

setfreq m16 ' 18M2 increase speed for 9600 baud
SerOut 6, T9600_16,("CL") 'Clear LCD 240 x 64 pixels
PAUSE 500
SerOut 6, T9600_16,("CL","SF",10) 'Clear LCD 240 x 64 pixels, set font to size 10
SerOut 6, T9600_16,("TP",0,4,"TT") ' Text has to be preceded with TT
SerOut 6, T9600_16,("hello World!")

I can give you a full programme that displays time, date, temperature (18B20) and pressure (MPS4115) and then graphs pressure, let me know.

I've got three lines connected, +5v, gnd and data (Rx pin on LCD unit). No inversion required, well T9600 does that.

I have spent some time learning about this display driver, it does work very well. The only command I cannot get working is the change baud rate one, but I ran out of time before the xmas break to send it binary speed data rather than ASCII numbers, I spoke to the supplier and he says that's what the problem is, so not a problem really.

PS I've got from that supplier the 12864 (128x64) LCD graphics unit, that's OK too. Serial, but needs a lot more to drive it (synchronous data) I use that on my Arduino project, I can give you the source code for a METAR (weather) reader if you need it. well it's on my web page under computing.
 
W

whiteoaks7

New Member
Thanks everyone, things for me to try. I had this from the supplier: "You can't connect it to RS232 directly, the voltage of RS232 is -15V to +15V, hope you didn't burnt out the display. This display can work with UART, the voltage is 0 to 5V, you need a voltage converter to convert RS232 to UART." which is a bit of a shock !!!! Frankly, as far as I know, a UART is a UART is a UART which certainly should be able to handle RS232 even in it's most aggressive form. (Wiki agrees: http://en.wikipedia.org/wiki/Universal_asynchronous_receiver/transmitter ). Anyway, I'll condition the signal and try again.

The purpose of using the PC is that development of the correct output ought to be easier to experiment with than a picaxe, the display can easily be powered from a USB and the serial plugged into a com port. Once the correct sentences are developed it's trivial to convert to picaxe basic (I hope).

Cheers Dave

OOOOps - nope! I got that wrong so red face and humble pie the signal has to be conditioned before it hits the UART :-(
 
Last edited:
G

Goeytex

Senior Member
Hi,

The attached circuit should work fine. It will convert and invert the RS232 +15 / -15 signal
from the PC to 0v / +5v TTL level for the display.

The 4148 diodes can be replaced with BAT85 Diodes for slightly better performance but will
work fine as is.

Have Fun
 

Attachments

G

g6ejd

Senior Member
UART signalling levels to me are digital logic levels, generally agreed to be 0/3.3v or 0/5v.

It would be much easier to trial this on a PICAXE, where you can test each command one by one, by contrast running from a PC serial port is frankly going to be a bit of trial and error until you get the polarities and data formats correct.
 
Last edited:
M

MPep

Senior Member
Frankly, as far as I know, a UART is a UART is a UART which certainly should be able to handle RS232 even in it's most aggressive form.
Click to expand...
Realistically, PIC, PICAXE, Arduino etc have UARTs in them, but only run at 3V3 to 5V (or there-abouts). Therefore, your assumption is incorrect.

Also, on the Ebay page listed, "Communication signal can work on 3.3V and 5.0V TTL"
 
You must log in or register to reply here.
Top