AXE033 LCD display issues

[evans_us]

Hi, after getting my code for the AXE033 LCD display to work in the simulator (great invention) I received my AXE033 kits. After putting one of these kits together and plugging into my picaxe28x1 I do not get any messages on the screen - even if I short the clock pins as suggested. There is no clock module attached.

I have checked all of the solder joints and they look very clean and no obvious connections to more than one pin. However, when I check with a ohmmeter I have some interesting connections. I soldered the headers directly between the 2 boards. I am driving with a 5VDC supply and I get 5V at the input header.
Looking at the connections on the LCD side (on the left) and checking with ohmeter to the pcb side I see the following connections to the PCB side (right pins)
lcd pin1=pcb pin1
lcd pin2=pcb pin2
lcd3=connects to pcb 1,3,5,7,8,9 and 10
lcd4=pcb4
lcd5=pcb 1,3,5,7,8,9,10
lcd6=pcb6
lcd7=pcb 1,3,5,7,8,9,10
lcd8=pcb 1,3,5,7,8,9,10
lcd9=pcb 1,3,5,7,8,9,10
lcd10=pcb 1,3,5,7,8,9,10
lcd11=pcb11
lcd12=pcb12
lcd13=pcb13
lcd14=pcb14
Can anyone tell me if this should be expected (looking at a working unit) and, if not what could be causing this? I want to solder the other unit but not without checking this one works first. With the 2 headers soldered this will be VERY difficult to disconnect.

Thanks for your help.
Evans_US

 

[westaust55]

AXE033 LCD display - module connections

Pins 1,5,7,8,9,10 are all connected to 0V.

Pin2 – Vdd
Pin3 – wiper 10K
Pin4 – leg 8 IC

Pin6 – leg 9 IC

Pin11 – leg 6 IC
Pin12 – leg 11 IC
Pin13 – leg 12 IC
Pin14 – leg 15 IC

In fact its exactly like the diagram in the PICAXE manual 3 pages 34/35 in terms of Vdd (5V), 0V and the contrast pot.

This information was already given previously by Tarzan and myself in another thread some time ago.

 

[Technical]

Have you adjusted the contrast? At full contrast you should at least get something on screen, e.g. a row of black boxes.

 

[rmeldo]

I have connected the two boards of my AXE033 with a header socket and header pins, in order to allow me to separate the two boards at any time.

the only thing I had to do was to make up new slightly longer spacers.

I can upload a photograph if required.

 

[evans_us]

In reply to Technical I see a row of black boxes on the top row when I adjust the contrast. It sounds like the connections are OK (Thanks WestAust) so I am going to try and use different pins on the picaxe to communicate with the device. My current code is shown below

symbol mosfet =1
symbol LCD=0
symbol LCDdly =1000 'delay when LCD displays text
'output0 (leg 21) =LCD
'output1 (leg 22) =mosfet

do
sertxd ("Testing SerTXD",13,10)
'This works - shows the picaxe is OK
pause lcddly
serout lcd,n2400,(254,128)
pause LCDdly
serout lcd,n2400,("n2400 LINE1 ")
pause LCDdly
serout lcd,n2400,(254,192)
pause LCDdly
serout lcd,t2400,("n2400 LINE2 ")
pause LCDdly
loop

I see the message using sertxd on my PC so I know the communications cable and picaxe are OK but nothing on the LCD.
Will change pin the lcd is connected to and see if this fixes it.
Any other suggestions? Should I just quit if I do not see the clock when shorting the clock pins?
How can I check the firmware chip is functioning?
Thanks

 

[Technical]

Are you connecting directly to output 0, not, for instance, incorrectly through the darlington driver chip on a project board (as in the starter pack).

 

[evans_us]

Connecting LCD

Yes I connect straight to the pin using a header.

 

[evans_us]

I just assembled the second LCD display and this worked right away!!
Nothing seems different between this and the non-functioning unit. It could be that the firmware chip is at fault - is there a way to check this? I could pull the functioning chip from the one display but am afraid to wreck this one since I need this for development.

 

[hippy]

It is unlikely the chip was faulty of the firmware was incorrect so the first course of action should be to double check that there are no shorts and that all solder joints are good. At least you have a good version to compare against which will help a lot.

You're right to be cautious about dismantling the working one to see if you can make the other work. That should really be a last resort, especially if you need a working unit; better to have one than none.