#23 LCD BIG DIGITS for your Arduino using I2C - Easy! 

Thanks Ralph. Although I wasn't looking to print large characters on an LCD however your video provided the answer to another problem I had.

Hi Ralph. Have these now been moved to a private part of your Dropbox?

Links updated to point to my Github (it was correct in the video description but not here). Oops.

Glad it was helpful! I want to use this font again in the near future.

Glad to help!

Excellent! That's great news, glad it helped.

I'm glad you're liking the videos, DocBanzai, and I'm sorry you experienced those frustrations with the LCD library. Normally I include the libraries I use in my GitHub but this one is an old video and I don't believe I have a GitHub repository for it. But, and this is important, you didn't give up and eventually got a working solution. Just think of the experience you've gained. Sounds like you should do well with that clock radio project! And yes, I repaired my boss' ZX81 once, much to his delight. Didn't get me promoted though.

@@RalphBacon Wish I still had my old ZX81, but that passed on many years ago. I've still got my Beeb which has been upgraded over the years and now runs everything from an internal SD card module which is great and I STILL mess with it from time to time! Just to go off on a complete tangent; referring to your video #5 (RTC modules) there was mention about a follow up video about the SQR and 32k pins on the module. I believe that SQR is a square wave generator and the 32k is some kind of non-volatile memory. Did you ever do this follow up or am I missing something? Please don't get me wrong, I'm not moaning! I think I've seen all your vids (more than once) and have never heard you mention it. I'm only asking as I'm curious whether the 32k (EEPROM I'm assuming) could be used as a sort of external storage device mainly for constant variables, strings etc. as I know the number of write cycles would probably be finite. I'm probably way off the mark but I hope you don't mind me asking. I have done (very) litle research but I'm kind of sticking to your vids for the time being as I prefer your style and, frankly, a lot of others just confuse me! Oh and just an idea but I've been reading about the TV-Out library that lets you output to tv, and it seems suspiciously simple. Is it something you're aware of or have tried? Haven't had the courage to try it yet as I don't want to blow up my TV! Thanks again!

Hmmm, long time ago that video... I probably did not follow up on the 32K EPROM because I instead did a video on the onboard EEPROM on the Arduino. Same principle but easier to use on the Arduino. I just didn't get a vibe that there was that much interest on (yet more) EEPROM space, on what is effectively an external device that not every project needs. Especially as it can't be used as run-time memory or program space. The SQR is indeed a square wave output that can be configured to 1Hz which can be useful to light up a LED every second (it looks very slow but really is 1 second). Could be useful for interrupts on the Arduino (to wake it up every second) but, once again, I never really explored that. Oh dear! But all these comments do make me rethink whether there are legs on any of those ideas for a future video (or part video), so thanks for that, it's all been added to my list.

When you say "double brackets" do you mean [ ] or [ ] [ ]? They both indicate an array, the first is a simple, one dimensional array like this: int scores[ ] = {9,8,7,6,5,4,3,2,1}; You then refer to each *element* of the array like this: Serial.print(scores[4]); which is actually the 5th element because arrays always start at zero: scores[0] value is 9 because that is the zero'th (first) element in the array. The second is an array of arrays. In the Real World think of it as a list of lists, such as a stack of boxes each with several colours of pencil in each. box 1 contains red, green pencils box 2 contains blue pencils box 3 contains yellow, red, orange and pink pencils Do you see how this can be considered a list (of boxes) of lists (pencil colours)? In C++ this might be described as: string boxes[ ][4] = {{"red", "green"}, {"blue"}, {"yellow", "red", "orange", "pink"}}; How to get the "yellow" colour? Serial.println( boxes [2][0]); Starting always from zero, this is the *third* box, first [0] colour within it. You can practice this here: www.tutorialspoint.com/compile_cpp_online.php which allows you to type in simple C++ stuff like this and execute there and then. Have a guess how I validated my examples?! Here's a complete example: #include using namespace std; int main() { string boxes[ ][ 3] = {{"red", "green"}, {"blue", "pink", "grey"}}; cout

yes i meant this double double [ ] [ ]. can you give an example on this one

The example is already in the reply above! It starts with the words "The second is an array of arrays..." Have a read and tell me what you think, Soliman.

Glad you like them! Oh, I just read, "...pool water temperature". Sigh. In my dreams.

@@RalphBacon 29dgC, sunny & warm! It's almost California weather today!

Glad it was helpful!

+Maxx B Glad you liked it. It's just not that complicated when it's laid out step by step, is it? If you have any suggestions for future videos just post them in the Discussions section or right here under any video!

+Ralph S Bacon I'm new to electronics and I suppose I could describe myself as a mature student. I've spent a lifetime programming, learning BASIC in the 80s and several languages since. Since an illness has left me partially disabled, I'm teaching myself electronics to try to keep my brain going and as exercise for my hands. The arduino is turning out to be a great way to incorporate my programming experience with electronics. My current project is to make an RF controlled vehicle using this pair of modules bit.ly/arduino-rf to provide the communication between the controller and the vehicle. I'd be interested to see a project using the Tx/Rx pair.

Sounds an interesting project (not to mention a challenge!). I will doubtless get round to the RF modules but before then I want to cover the various wi-fi modules (ESP8266) and the bluetooth module. If you can code then the electronics will be less of a challenge (most people in the Arduino forum face challenges with coding). So much to cover and so little time to do it all in. Stay tuned for future videos and do spread the word if at all possible :)

I use a wooden, red chopstick now, much safer!

Yes, a later version of the library made this breaking change, very bad not for it to be backward compatible.

Hi Vibhor, let's see. If you are using my unchanged LCD_CustChar_Demo_2 then it is line 107 that is causing you issues. The code stops there whilst PIN 7 (GPIO D7) is HIGH. You must connect D7 to GND for the code to continue. Or else just comment out the line that reads: while(digitalRead(7)) { } I hope this helps!

Glad you liked it Hung Viet! I use the Big Digits every day in my Wireless Rain Sensor receiver (video #54) and it works very well. I can read the temperature the other side of the room. Thanks for posting.

I am using the nodemcu module and I have also done it. Thank you for sharing

Glad you liked it Soliman. I used the big digits in another project to tell me when it was raining so I could bring the cat basket and stuff in - the big digits display the temperature, all described in video #48. Thanks for posting.

You can do this but not by using a pot. 😱 Background: The LED is on pins 15 & 16 on the LCD module and the jumper connects pin 15 to VCC. Pin 16 is then controlled by an NPN transistor on the backpack module. If you remove the jumper, you can control the power at pin 15 (VCC) by connecting to one of the bare jumper connections (your multimeter will tell you which one is connected to pin 15 on the backpack). You could easily turn the LED on and off just by connecting it to a digital pin on the Arduino (warning! measure the current being drawn first, across the jumper, must be less than 20mA, probably is). To control the brightness in a more granular fashion, you can use PWM on a digital pin that supports it too by using AnalogWrite (I'm guessing you know all this).

You're awesome Ralph 👍many thanks! No, I didn't know all of this, the info you gave me was exactly what I was looking for! Thank you very much.

My module's jumper print claims the jumper shorts "5v to Gnd" 🙄

The 5v (VCC) goes to the LED first (via the jumper) then to ground via the transistor - at least, that's what the schematic shows. If there is no transistor present then it would need a resistor to limit the current, probably 200Ω or thereabouts.

Aha! Many thanks for everything Ralph!

Thank you, R Willis, appreciated.

There is a function in the Liquid Crystal library to turn blinking on and off. Ensure you have not called that. Also, check that it really is blinking and not your code displaying a value, then displaying blanks, then displaying a value again - it looks like it is blinking but is not. I would change the sketch to display the values of A0 and A1 _separately_ first, and then combine them.

Can you help me. I want to display 2 adcs with lcd 1602. but when I print. displayed value. A0 blinking . A1 is good

You say it stops at lcd.begin(). That sounds like it hasn't found the I2C screen. Did you first load the 'scanner' sketch to get the address of the screen? It might be the default 0x27 but could be some other address - no point in guessing, load the scanner.ino and see what it finds.

Well, the example sketches I provide should easily get you started, and if you use an ESP32 you can join a Wi-Fi network to get the time (the ESP32 auto-syncs the internal time against real-time).

Without re-engaging my entire thought process for this design, I'm assuming my characters are taller and use the entire set of pixels?

@@RalphBacon yes, OK. I made a mistake. LCD pixels are 5x8, not 5x7. When I use the LiquidCrystal_I2C.h library and I do lcd.print(line), where line is a character string, I only see 7 lines of pixels (if my vision is not too cloudy). This must be because the folks that wrote that library wanted to keep a small space between the 2 lines of the display. Sorry to bother you for that!

No bother, Bill, it's all a learning experience!

You're undoubtedly right, but in a single project I guess it would be unusual to use more than one, right?

@@RalphBacon Yes but they don't all have unique addresses as you described. just one or the other.

+zoran b I can't find a register command for the HD44780 chip (that controls the LCD) to put it into 'sleep' mode but one way (given that you are putting the Arduino into deep sleep) is to control the power to the LCD via the Arduino (either a logic-level MOSFET or an NPN transistor) on a standard GPIO pin. Switch the LCD on when you come out of deep sleep, wait 50ms for the LCD to initialise (says the datasheet, but you may need to give it a bit more time) and you are on your way. Shut off the power via the Arduino just before you set the Arduino into deep sleep. I hope this helps! And thanks for the interesting question.

Simply download the example sketch of mine from my GitHub and see how that works. It's all straightforward. I have just done exactly that for a project I am working on for this Friday's video! What a coincidence! Have a look at what I do there (also a time display).

what a person you are?thanks a lot brow. i will try with this.

In the description! github.com/RalphBacon/LCD_Big_digits

I will sort this out in a day or so, thanks for letting me know. What's happened is that Dropbox has removed the public access to the files. I will move them to a Github repository as soon as I can. I'll update here when that is done.

Links in the comments updated to point to my Github. Video description was already up to date. Enjoy!

It's all in my GitHub repository, József: github.com/RalphBacon/LCD_Big_digits Enjoy!

Indeed, Brian, indeed. But we must accept that and be creative! The big digits I use (in daily use showing the outside temperature in Benny's cat run) is very readable across the room. And perhaps this is where the custom characters excel, rather than defining a whole raft of them. But, as you say, if only the chip manufacturer had allowed a full 128 though, or 256, or... oh well!

Ha ha! Yes, I'm using the big digit code on my Smart Heater Controller in my workshop. I literally just copied and pasted my original code (from an Arduino) into the sketch for my ESP32 and it "just worked". How good is that?

That means your I2C device is not connected up correctly (or powered incorrectly). Check SDA vs SCL lines. You need it to be recognised to move forwards. Try another I2C device (any kind) to prove your sketch is working OK. You're running this on an Arduino Uno?

Pease add your reply to _this thread_ and don't repost another topic!

I cannot think of a way to test LCD so ordered another, however I connected an LED in series with a resistor clock and data both showed the Uno to be active. I don't have any other I2C items. Thank you for your time.

Once you have your scanner sketch telling you that it has found something on the I2C bus, your LCD sketch (to prove it works) should look like this: #include #include // Set the LCD address to 0x27 (default) for a 16 chars and 2 line display LiquidCrystal_I2C lcd(0x27, 16, 2); void setup() { // initialize the LCD lcd.begin(); // Turn on the backlight and print a message. lcd.backlight(); lcd.print("Hello, world!"); } void loop() { // Do nothing here... } Pins A4 and A5 are SDA and SCL respectively.