AXE133 LCD no output.

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caseybee

New Member
Testing my AXE133 LCD for the first time and I get no output. Running the simple "Hello" program produces nothing. I would assume that the display in general would light up when power applied but it doesn't. I have tested for 5v H3 OK. What other tests can I do?

Do I have a LCD or OLED? I purchased the 'Budget Serial LCD Module' but there was no VR1 (not required for OLED) in the kit.

Any thoughts?
Keith
 
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nick12ab

Senior Member
caseybee said:
Do I have a LCD or OLED? I purchased the 'Budget Serial LCD Module' but there was no VR1 (not required for OLED) in the kit.
Click to expand...
Before the crystal ball joke comes up, check the module. If the screen is a light grey or light green colour then you have an LCD but if it is dark purple or black, it's an OLED.



From the fact that nothing's come up on the display without VR1 fitted, it will probably be a LCD.

Just fit VR1 and the module will work. Any variable resistor between 4.7K and 20K will do.
 
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caseybee

New Member
Thanks Nick. So I do have an LCD as I thought. Now to find a suitable variable resistor. Should there have been one in the kit?

Keith
 
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EricD

Member
The Axe133 is an LCD which is what you have. The OLED version is Axe133Y and costs more (nearly twice as much) than the 'Budget Serial LCD Module'. I bought the same one a few weeks ago, VR1 was included.
 
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Brian M

Member
Keith

Yes, Had one in my budget kit 10K miniature skeleton pre-set. Check the list in the AXE133 data sheet.

Brian
 
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nick12ab

Senior Member
caseybee said:
Thanks Nick. So I do have an LCD as I thought. Now to find a suitable variable resistor. Should there have been one in the kit?
Click to expand...
The impression I get from the datasheet is that it should have been included.
Code
Qty
Description
PCB
1
AXE133 PCB
Display
1
16x2 OLED or 16x2 LCD or 20x4 OLED
IC1
1
PICAXE-18M2 preprogrammed with AXE133 firmware
IC1
1
18 pin IC socket
R1
1
22k resistor (red red orange gold)
R2,3
2
10k resistor (brown black red gold)
C1
1
100nF capacitor
CON1
1
3.5mm download socket
H1,2
2
10 pin header (snap to length as required)
VR1
1
10k preset (not required for OLED kits - LCD Contrast)
Click to expand...
You could use a potential divider until you get the pot - or just a resistor between the wiper pin and the ground pin of where the pot went. Or just use any 9mm trimmer pot such as this one or this one.

Rev-Ed might send you a free one next time you order to make up for not including it.
 
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fierojo

New Member
I've built about 3 or 4 of the AXE033Y displays and they have all worked immediately upon power application. There's a two line message. Forgot what the first line was, but the second was www.picaxe.com. I'm looking at another project involving the 134Y (4x20 OLED). I built it but it did not light up and won't display information from a known good source. I swapped the M2's from another OLED display and it still doesn't work. Tech support is suspecting a solder issue. Possible, but I'll have to rip the display from the conversion board, which is some I'm not looking foward to to verify. Hopefully the error is mine.

Also, since I'm on the topic, what is the control command to get the cursor to the third and fourth lines of the 133Y display? It's not in any information which comes with the display or the AXE008 data sheet.

Thanks.

S. Joe Wynman
 
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nick12ab

Senior Member
fierojo said:
Tech support is suspecting a solder issue. Possible, but I'll have to rip the display from the conversion board, which is some I'm not looking foward to to verify. Hopefully the error is mine.
Click to expand...
You don't have to - use a multimeter set to continuity range to check for a) shorts between connections and b) continuity between 18M2 board and the OLED module.

fierojo said:
Also, since I'm on the topic, what is the control command to get the cursor to the third and fourth lines of the 133Y display? It's not in any information which comes with the display or the AXE008 data sheet.
Click to expand...
Line 3 is a continuation of line 1 and line 4 is a continuation of line 2, so for line 3 use (128 + 20) = 148 and for line 4 use (192 + 20) = 212.
 
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caseybee

New Member
Found a resistor (RES030), don't know why I ordered one months ago. Lucky me. Now to unsolder the boards. Do I unsolder the LCD board or the daughter board? Any suggestions?

Keith
 
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nick12ab

Senior Member
caseybee said:
Found a resistor (RES030), don't know why I ordered one months ago. Lucky me. Now to unsolder the boards. Do I unsolder the LCD board or the daughter board? Any suggestions?
Click to expand...
Isn't the AXE133 PCB double sided? If that is the case, then just insert the pot into its holes and apply the solder from the accessible side without removing the PCB from the LCD.
 
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nick12ab

Senior Member
caseybee said:
Did wonder if that could be done. I think I will wait until I see my kit builder.
Click to expand...
Kit builder?

Someone builds your kits for you?

That's no fun! Most of the fun with kits is in building kits yourself. And then you learn in the process.
 
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john2051

New Member
Hi, I got my 20x4 oled display kit, and it worked first time!. The thing you have to watch though, the pins are different on the 20x4 oled, ie pins 15 and 16 are the
opposite end. Good job I checked, I wondered if that was the problem one of the other members was having.

I never solder the axe133 pcb to the display, I always use 16 way sil plugs and sockets, then if either the board or the display fails all is not
lost.

All the best john
 
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michaelmichael

New Member
Thanks for the LED / OLED photographs. I've got a mixture of OLEDs and LED displays - all nominally ordered as OLEDs but maybe not clear on my part and certainly not clear from the catalogue. And not a single pot in sight! At5 least I now know why the last 2 I built won't display. Thanks to all but the packers!
 
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caseybee

New Member
Finally got round to fitting pot. Unfortunately still no display! Checked that there is 5v on H3 OK. Plugged cable into socket and checked 18M2 working OK. Checked there no shorts on H1 OK. Any suggestions for other tests I can do?

Regards
Keith
 
Technical

Technical

Technical Support
Staff member
michaelmichael said:
all nominally ordered as OLEDs but maybe not clear on my part and certainly not clear from the catalogue. And not a single pot in sight! At5 least I now know why the last 2 I built won't display. Thanks to all but the packers!
Click to expand...
To clarify - OLED kits do not include the 10K as it is not used on OLED kits. However for LCDs it is required *and* must be adjusted to set the contrast correctly.

caseybee said:
Plugged cable into socket and checked 18M2 working OK. Checked there no shorts on H1 OK.
Click to expand...
Have you reprogrammed the AXE133 on-board 18M2? Some users have misunderstood and tried the sample 'serout' programs on the AXE133 module itself, instead of a different PICAXE chip 'linked' across to the AXE133 module. The 18M2 on the LCD board is generally not reprogrammed - it simply runs the AXE133 firmware all the time.
 
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caseybee

New Member
No black rectangles!
Just tried programming the output pins C.0, C.1 & C.2 on H3. Initially all low. After (255, #00000111) then only C.0 High. After (255, #00000000) all low again. After (255,#00000100) only C.0 High. This shows something getting through but not correctly. So is it the display or something else?

Keith
 
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nick12ab

Senior Member
caseybee said:
No black rectangles!
Just tried programming the output pins C.0, C.1 & C.2 on H3. Initially all low. After (255, #00000111) then only C.0 High. After (255, #00000000) all low again. After (255,#00000100) only C.0 High. This shows something getting through but not correctly. So is it the display or something else?

Keith
Click to expand...
# is for ascii conversion, you need to use % if you want to specify a number using binary. The PICAXE's outputs won't affect whether the black squares appear or not so I suggest you build a simple circuit on breadboard with just the LCD and a power supply with pins 1 and 3 to ground and pin 2 to 5V and see if the black blocks appear then.
 
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caseybee

New Member
Oops! the 3 outputs now work correctly. So only problem is nothing on the display. Presume it's back to Techsupplies.

Keith
 
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nick12ab

Senior Member
caseybee said:
only problem is nothing on the display. Presume it's back to Techsupplies.
Click to expand...
Have you done what BeanieBots suggested?
BeanieBots said:
When you turn the contrast fully up, do you get black rectangles?
If not, there is wiring problem.
Click to expand...
And if that didn't work, did you try what I said?
nick12ab said:
The PICAXE's outputs won't affect whether the black squares appear or not so I suggest you build a simple circuit on breadboard with just the LCD and a power supply with pins 1 and 3 to ground and pin 2 to 5V and see if the black blocks appear then.
Click to expand...
 
Technical

Technical

Technical Support
Staff member
If the LCD never shows any black triangles when you move the contrast pot all the way from one end to the other it normally implies a soldering issue somewhere. Have you used a multimeter to measure voltage on pins 1, 2 and 3 on the actual LCD (1=0V, 2=V+, 3=contrast).Pin 3 value should change between 0V and V+ as you move the pot.
 
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caseybee

New Member
As per my reply to BeanieBots, no black rectangles when adjusting pot. Connecting just power to 2 and gnd to 1 and 3 produces nothing.

Checking LCD pins: between 1 and 2 gives 5v, between 1 and 3 always gives 5v for all adjustment on the pot!

Keith
 
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nick12ab

Senior Member
Just an idea for testing that you've got it soldered right - in the image below which pin on the LCD is pin 1 - A, B, C or D? No peeking below the picture!


Click to view large version

Please use the mouse to highlight the following in order to read the text (you can do this by triple-clicking anywhere between the two inward-pointing arrows):
> If you answered anything but C then it it very likely that you have connected the LCD incorrectly to the AXE133. You need to have it so that all 16 holes on both LCD and AXE133 line up. <
If after this it still doesn't work, then this might be of help.
 
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caseybee

New Member
Thanks for the info. C was the position I had worked out. Looking at your diagnostic guide, where are Vss, Vdd and Vo?

Keith
 
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nick12ab

Senior Member
Vss (aka Ground) is pin 1, Vdd (aka power, 5V) is pin 2 (which is to the left of pin 1 when looking at the LCD from the front) and Vo is pin 3 and is the contrast control.
 
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DDJ2011

Member
I have the same problem with my lcd - ie no resistor...wonder if there has been a packing glitch?

Lots of things to try here to get it working again though which I will have a go at over the next few days.
 
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nick12ab

Senior Member
Remember that in my flowchart all voltages are in relation to Vss unless otherwise stated.

caseybee said:
Nick. Vo is the same as Vdd therefore fail with second box on the right. Which means?

Keith
Click to expand...
The contrast on LCDs (Vo) is relative to Vdd so in general in order to see something on the LCD, Vo needs to be -4V or less (e.g. -6V as it's negative) in relation to Vdd. Modern standard temperature range LCDs such as the one included with the AXE133 don't require Vo to be less than -5V in relation to Vdd so you can use a single supply and connecting Vo directly to Vss (which is ground) when the supply (Vdd) is 5V will make the display quite dark.
 
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Captain Haddock

Senior Member
Occaisionally some idiots get vdd & vss the wrong way round, it's easy to tell as you get a burning smell while trying to work out why nothing is displaying, what sort of idiot would do that I hear you say?
:eek::eek::eek: Take a guess, it was only 2 days old too :( At least it was only a cheap ebay jobbie, new one ordered).
 
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nick12ab

Senior Member
The way to remember it is Vdd goes to the drain of a MOSFET (through a load) and Vss goes to the source of a MOSFET.

My method of protecting investments is to fit a 5.1V zener diode which depending on power will cap the voltage and/or short protecting the device from harm.
 
Technical

Technical

Technical Support
Staff member
DDJ2011 said:
I have the same problem with my lcd - ie no resistor...wonder if there has been a packing glitch?
Click to expand...
We have checked all our shelf stock and they are correct - AXE133 has the 10k preset, AXE133Y does not.
However anyone who thinks they had one missing can contact us for a replacement.

caseybee said:
Checking LCD pins: between 1 and 2 gives 5v, between 1 and 3 always gives 5v for all adjustment on the pot!
Click to expand...
That is not correct and is probably the issue. Look for a short between pins 2 and 3.
If you can't adjust the voltage on pin 3 between 0V and 5V you simply can't adjust the contrast, so the LCD will never work until this is resolved.
 
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nick12ab

Senior Member
Well I was in the process of preparing and uploading an image of a quick schematic but then Technical posted, so...
If after checking your AXE133 module the LCD still doesn't work, you can rule out the LCD being faulty by building this circuit on some breadboard.
 
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caseybee

New Member
Some progress! Shorting pins 1 and 3 gets the display to show (as per Nicks previous post). Hurrah! The LCD does work OK.

This means the problem must be on the daughter board I presume. I can not find a short between 2 and 3 (or any others). Pin 3 is connected to the centre of the pot. Adjusting the pot changes the reading between 3 and the other sides of the pot. So where to next? Presume the problem is under the board so will have to remove it. I can either unsolder the daughter board or the LCD, which do you recommend?

Thanks for help so far. Keith
 
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nick12ab

Senior Member
I'd unsolder the board since the LCD is known good but the board might not be so desolder the board to prevent any potential damage to the LCD.

But if adjusting the pot changes the reading between 3 and the other sides of the pot then the other pins of the pot can't be shorted. Before disassembling the assembly, check for shorts between pin 3 and pin 4 of the LCD connector.
 
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nick12ab

Senior Member
caseybee said:
Short between 5 and one side of the pot.
Click to expand...
That's intentional. Pin 5 of the LCD (R/W) goes to ground as it is not required. If one side of the pot goes to power (Vdd) and the other goes to ground (Vss) then the short you're looking out for is between the wiper and anything else.

When you did your resistance check, did you make sure that one probe was on the LCD itself and not just on the pot? Please check continuity between the pot wiper and LCD pin 3 (Vo).
 
hippy

hippy

Ex-Staff (retired)
caseybee said:
I can either unsolder the daughter board or the LCD, which do you recommend?
Click to expand...
Having made something of a pig's ear of doing that myself I would perhaps recommend cutting the connector in half to separate the two ( carefully do a pin at a time to not strain connection points ), and unsolder each. That way you're only unsoldering one pin at a time not trying to do the whole lot together.

And perhaps throw an order in for 0.1" header sockets and pins so you can use / try different LCD / OLED with the same board. Put header sockets on the board is my recommendation as you are likely to have more LCD's than boards when they come to execute your will and it'll be cheaper.
 
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caseybee

New Member
Wiper to LCD pin 3 pad is a short. Wiper is not shorted to anything else that I can get at (except one side of unused C3 under a label).

Thanks for your patience, there can't be much more to check?
 
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