So my little arduino clone is fun but I was wondering something
-
You should check whether the display takes inverted serial input instead of normal.
The difficult we do right away... ...the impossible takes slightly longer.
That's interesting. I wouldn't know since this kit has zero instructions. It's a clone of the Arduino Mega 2560 and presumably all of the gear in the kit (like the display) is supposed to work out of the box just like the arduino stuff. If not, then I may as well throw it away since there are no instructions. That said, the pinouts for this LCD and the one in the Arduino provided sample are all labeled the same except 2 pins have a different name on the schematic - "A" vs "LED+" and "K" vs "LED-" but i think they are the same thing, given the other 14 pins are identical, and those are for the backlight according to the schematic
Real programmers use butterflies
-
Some displays require you to send a command to turn on the backlight.
The difficult we do right away... ...the impossible takes slightly longer.
I'm almost certain this one is voltage controlled based on the schematic I'm working with - it's got a potentiometer wired between one of the pins and the power source.
Real programmers use butterflies
-
It's 5vdc from the looks of it. I would think I'm certain having checked multiple times, but the display disagrees with me, since it just sits there dead as a fish when it's supposed to be printing "Hello World" I need to order a multimeter from amazon. I suppose I'll do that today.
Real programmers use butterflies
Assuming the connections are proper, the backlite should work if power is present. Are the character segments doing anything (I'm guessing it's a 16x2 or similar)? It's been my experience that the segments 'get slightly darker' when power is applied, regardless of backlite. Also, there's the contrast voltage to consider.
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment "Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst "I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
-
Assuming the connections are proper, the backlite should work if power is present. Are the character segments doing anything (I'm guessing it's a 16x2 or similar)? It's been my experience that the segments 'get slightly darker' when power is applied, regardless of backlite. Also, there's the contrast voltage to consider.
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment "Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst "I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
jeron1 wrote:
It's been my experience that the segments 'get slightly darker' when power is applied, regardless of backlite
Thank you! That's helpful. It's not doing anything - it's as dead as fish, meaning I've either wired it catastrophically wrong or it came dead on arrival. I've checked the wiring many times, so at this point I'm kind of at a loss. It's why I wanted to know if anyone knew how to simply get power to thing just so I can prod it for signs of life.
Real programmers use butterflies
-
jeron1 wrote:
It's been my experience that the segments 'get slightly darker' when power is applied, regardless of backlite
Thank you! That's helpful. It's not doing anything - it's as dead as fish, meaning I've either wired it catastrophically wrong or it came dead on arrival. I've checked the wiring many times, so at this point I'm kind of at a loss. It's why I wanted to know if anyone knew how to simply get power to thing just so I can prod it for signs of life.
Real programmers use butterflies
Does turning the pot from one extreme to the other do anything noticeable?
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment "Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst "I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
-
Does turning the pot from one extreme to the other do anything noticeable?
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment "Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst "I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
Nope. I even tried wiring/shorting around the pot but nothing.
Real programmers use butterflies
-
jeron1 wrote:
It's been my experience that the segments 'get slightly darker' when power is applied, regardless of backlite
Thank you! That's helpful. It's not doing anything - it's as dead as fish, meaning I've either wired it catastrophically wrong or it came dead on arrival. I've checked the wiring many times, so at this point I'm kind of at a loss. It's why I wanted to know if anyone knew how to simply get power to thing just so I can prod it for signs of life.
Real programmers use butterflies
honey the codewitch wrote:
I've either wired it catastrophically wrong or it came dead on arrival
If you bought it off of ScamBay then this could be the problem. Selling broken electronics is a huge thing on the auction sites. I avoid the batteries too... I saw a clear pattern from multiple sellers where they would sell me 50% good batteries and the other half bad. I've got some really good stories to tell about ScamBay... I once bought some flood lights off the site. I bought eight of them and the seller only sent me six. He fought me in the dispute and I suddenly realized that I could use the FedEx package weight to prove that it was impossible that the shipment contained 8 of them. Best Wishes, -David Delaune
-
Nope. I even tried wiring/shorting around the pot but nothing.
Real programmers use butterflies
The pot is for contrast so you generally can't go around it (unless you're using fixed resistors). The fact that the backlite does nothing, is suspicious like there's no voltage. Without a multimeter it's difficult say, you wouldn't happen to have a discrete LED and a 1K resistor, that you could use as a kind of 'voltage' probe?
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment "Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst "I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
-
The pot is for contrast so you generally can't go around it (unless you're using fixed resistors). The fact that the backlite does nothing, is suspicious like there's no voltage. Without a multimeter it's difficult say, you wouldn't happen to have a discrete LED and a 1K resistor, that you could use as a kind of 'voltage' probe?
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment "Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst "I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
Yeah but I'm not sure which pins i need to check. I think i know which are the data pins, but the control pins labels aren't very clear. It's why I was hoping someone could tell me at minimum, which of the 16 pins on this apparently standard LCD interface I need to wire up to show signs of life.
Real programmers use butterflies
-
honey the codewitch wrote:
I've either wired it catastrophically wrong or it came dead on arrival
If you bought it off of ScamBay then this could be the problem. Selling broken electronics is a huge thing on the auction sites. I avoid the batteries too... I saw a clear pattern from multiple sellers where they would sell me 50% good batteries and the other half bad. I've got some really good stories to tell about ScamBay... I once bought some flood lights off the site. I bought eight of them and the seller only sent me six. He fought me in the dispute and I suddenly realized that I could use the FedEx package weight to prove that it was impossible that the shipment contained 8 of them. Best Wishes, -David Delaune
Got it new off amazon. Only concern is it is a knockoff made my elegoo and not an arduino branded kit. It was a lot cheaper so if i have to order a replacement LCD screen I'm probably still money ahead. :) Although that's not taking into account the aggravation of testing an LCD screen for signs of life.
Real programmers use butterflies
-
Yeah but I'm not sure which pins i need to check. I think i know which are the data pins, but the control pins labels aren't very clear. It's why I was hoping someone could tell me at minimum, which of the 16 pins on this apparently standard LCD interface I need to wire up to show signs of life.
Real programmers use butterflies
I would check pins 1 and 2, generally pin 1 is ground and pin 2 is 5v, if you don't have this nothing else matters. Similarly, pin 16 is ground for that backlite and pin 15 is the current limited 5v input for the backlite.
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment "Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst "I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
-
Is it a 5 volt display or does it use some other voltage? Are you sure you have the power connected to the correct pins?
The difficult we do right away... ...the impossible takes slightly longer.
First thing to do: Check your wiring, especially ground and the supply voltage. If that does not help, get yourself the datasheet of the display (the one that you have, not the one you assume you have!). I have had such things before. in my case it was a MAX232 Rs232 level shifter. I wired it up according to the datasheet from Texas Instruments and the output voltage levels were not anywhere near RS232 specifications. Then I got the original datasheet and one of the external capacitors was indeed connected to ground instead of VCC. Now it actually works. Edit: Have you tried to read something from the display's registers instead of writing? This way you might cut some corners. I would also take a look at the signals with my oscilloscope, but I assume you don't have one just waiting for something to do...
I have lived with several Zen masters - all of them were cats. His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
-
Does anyone know what the simplest circuit to use for a 16 pin LCD hitachi style display is to make it display *anything* or even turn on the backlight? I got a new kit and I can't seem to get the LCD display to respond at all, and I'm not finding the answer to this anywhere. All the examples I can find use a library, and require the thing to be fully wired up. The problem is, after having done that, even after double checking and triple checking my wiring against the examples it still didn't work. I need something simpler just to do a basic power-on sanity check for the LCD. I have no idea what the hitachi display protocol looks like in practice and the pins aren't very descriptive. I know there are some arduino-heads here on CP. Can I get that LCD to do anything at all with two or three connections?
Real programmers use butterflies
I have had these exact problems with these[^]. If one data line isn't connecting exactly properly then you will not see anything. I switched to the ones with the I2C interface [^] (only 3 lines to worry about) and I was much happier. I also had the problem with a 8x2 and I posted the issue (with pictures) at : character lcd - With power only on this LCD, will I see anything? - Electrical Engineering Stack Exchange[^] That may provide some additional insight. When you get your multimeter you'll probably discover that either one of your jumper wires is bad or you'll discover that one of your breadboard connections is fouled out. That's what has gotten me in the past. Good luck.
-
I would check pins 1 and 2, generally pin 1 is ground and pin 2 is 5v, if you don't have this nothing else matters. Similarly, pin 16 is ground for that backlite and pin 15 is the current limited 5v input for the backlite.
"the debugger doesn't tell me anything because this code compiles just fine" - random QA comment "Facebook is where you tell lies to your friends. Twitter is where you tell the truth to strangers." - chriselst "I don't drink any more... then again, I don't drink any less." - Mike Mullikins uncle
Thank you! I'll give that a whirl.
Real programmers use butterflies
-
I have had these exact problems with these[^]. If one data line isn't connecting exactly properly then you will not see anything. I switched to the ones with the I2C interface [^] (only 3 lines to worry about) and I was much happier. I also had the problem with a 8x2 and I posted the issue (with pictures) at : character lcd - With power only on this LCD, will I see anything? - Electrical Engineering Stack Exchange[^] That may provide some additional insight. When you get your multimeter you'll probably discover that either one of your jumper wires is bad or you'll discover that one of your breadboard connections is fouled out. That's what has gotten me in the past. Good luck.
Grrr, yes it is one of those 16 pin interface LCDs. I think you're probably right that it's a bad jumper wire or something. I guess I need to go ahead and order a multimeter. I just overlooked it when i got the kit.
Real programmers use butterflies
-
Grrr, yes it is one of those 16 pin interface LCDs. I think you're probably right that it's a bad jumper wire or something. I guess I need to go ahead and order a multimeter. I just overlooked it when i got the kit.
Real programmers use butterflies
Get yourself the datasheet and take a good look at the pinout of that connector. Never assume anything. Guessing never helps.
I have lived with several Zen masters - all of them were cats. His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
-
Get yourself the datasheet and take a good look at the pinout of that connector. Never assume anything. Guessing never helps.
I have lived with several Zen masters - all of them were cats. His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
I know that the pinout is a de facto standard 16 pin interface for small LCDs like this. I don't need to assume anything about it. I just need to get it to respond. A multimeter will help. A datasheet won't solve my current issue.
Real programmers use butterflies
-
I know that the pinout is a de facto standard 16 pin interface for small LCDs like this. I don't need to assume anything about it. I just need to get it to respond. A multimeter will help. A datasheet won't solve my current issue.
Real programmers use butterflies
And some guy in China never heard of your de facto interface or had his own ideas. Are the signals at least labeled on the display's board? That would help a little, even without the datasheet.
I have lived with several Zen masters - all of them were cats. His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
-
And some guy in China never heard of your de facto interface or had his own ideas. Are the signals at least labeled on the display's board? That would help a little, even without the datasheet.
I have lived with several Zen masters - all of them were cats. His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
They're labeled, but not in way that's helpful. Let me put it this way. The LCD is either the standard hitachi interface for it, just like the one the genuine arduino has, or it's just garbage because exactly one person knows how to use it and that's the person that designed it. if that's the case, no datasheet exists. So datasheets still aren't the solution.
Real programmers use butterflies
-
Does anyone know what the simplest circuit to use for a 16 pin LCD hitachi style display is to make it display *anything* or even turn on the backlight? I got a new kit and I can't seem to get the LCD display to respond at all, and I'm not finding the answer to this anywhere. All the examples I can find use a library, and require the thing to be fully wired up. The problem is, after having done that, even after double checking and triple checking my wiring against the examples it still didn't work. I need something simpler just to do a basic power-on sanity check for the LCD. I have no idea what the hitachi display protocol looks like in practice and the pins aren't very descriptive. I know there are some arduino-heads here on CP. Can I get that LCD to do anything at all with two or three connections?
Real programmers use butterflies
I don't now what specific device you're talking about, as you only specified "16 pin"; some identification could have been useful, or even a link to the thing you bought. However, most low-end LCD displays include a control chip that is either a Hitachi HD44780 or some derivative thereof. It has been launched over 30 years ago, it got its own Wiki page here[^] and you can find its complete datasheet everywhere[^]. I used it a couple of times, but that was long ago (using 8-bit microcontroller and assembly code); I can't remember but I would expect the backlight to be working as soon as you apply 5V to the appropriate pins with a double caveat: My best guess is you already killed the backlight, either by applying a reverse voltage, or by not including a series resistor; some if not all such LCD displays need a resistor in pin 15, and yes there are Youtube-quality instructions that don't show that. But this one does.[^] Anyway the best way to test is by properly connecting everything up, and sending the appropriate commands and data. A library is not essential, you could perform each of the steps required using simple instructions, even when the backlight isn't working (use incident light at an angle of some 45 degrees). It is all a matter of sending some bytes to some addresses (which is true for all software of course). Using the Arduino "LiquidCrystal" library can make it a little easier: Example (warning: the essential resistor is lacking here!)[^]. :) PS: You can't just try and retry until it works, your hardware deteriorates when maltreated so you better get it mostly right from the start. It ain't software, it is called hardware for a reason.
Luc Pattyn [My Articles] If you can't find it on YouTube
