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9 votes

My program is using too much memory

There are lots of repetitions in your code. This is something you should generally avoid, not only because of memory usage, but also, and most importantly, because of maintainability. The most common ...
Edgar Bonet's user avatar
  • 43.3k
8 votes
Accepted

Confused between SPI and I2C for SSD1306 OLED

SCK and SCL are the same thing. Serial ClocK Serial CLock They seem to be interchangeable. The fact you have SDA (Serial DAta) as opposed to separate SDI / SDO or MOSI / MISO pins means it's I2C. ...
Majenko's user avatar
  • 105k
7 votes
Accepted

Frequent ON OFF in SSR

You need to implement hysteresis. Set two temperature points around set_temp. One a little higher to be a limit for turning the heater off and a one a little lower then set_temp to turn the heater on. ...
Juraj's user avatar
  • 18k
5 votes
Accepted

Need help with 2X3 matrix for braille

First of all, may I say "Thank you" for helping your friend like that? I cannot think of a better way to use an Arduino than as a driver for a Braille display like you describe! As you know, Braille ...
5 votes

Image Breakdown

240 by 320 pixels. That's 76800 pixels. In your example it looks like you want 3 bytes per pixel, so that's 230400 bytes. An Arduino Mega has 8K bytes of SRAM memory. There's enough room in the ...
Delta_G's user avatar
  • 3,366
5 votes
Accepted

Image Breakdown

I presume you are trying to create a system that has one image stored, and want the image to be available without needing an SD card reader on the system. If the logic of your program is small enough ...
James Waldby - jwpat7's user avatar
5 votes
Accepted

Can't get 4 digit 7 segment display to show different values

You have a common cathode display and all your cathodes are tied to ground through resistors. You have no way at all of separating out the different digits. You cannot directly drive such a display ...
Majenko's user avatar
  • 105k
5 votes

Arduino freezing with OLED display

Because your program uses various String objects in several different sizes, there's a good chance that heap memory (in RAM) is getting fragmented to the point that String allocation begins to fail, ...
James Waldby - jwpat7's user avatar
5 votes

How to show the º character in a LCD?

Some displays have different characters above 128. It is best to make your own character. That is what @dannyf ment with "CGRAM". The custom characters are stored in CGRAM. There is no need to read ...
Jot's user avatar
  • 3,246
4 votes
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Code runs different on USB vs Battery

The USB provides the one thing that is missing from your diagram there: the common ground. The GND pins of the two boards must be connected together. By using USB the USB becomes that connection. As ...
Majenko's user avatar
  • 105k
4 votes
Accepted

Show images on a monitor using Arduino via Wifi

I have somewhere in my stash a shield that enables an Arduino to overlay graphics on the screen. But it is kinda crude and low-res. What you're trying to achieve is definitely not for Arduino, it is ...
dda's user avatar
  • 1,588
4 votes

Need help with 2X3 matrix for braille

Each character will be 6 bits (so let's use a byte to store it) and we'll use the following bit to LED mapping bit0 bit1 bit2 bit3 bit4 bit5 Now you just need an array of bytes where each byte ...
KennetRunner's user avatar
4 votes
Accepted

Arduino code to run 2 thing simultaneously

Arduino Microprocessors are mostly single core devices and thus are unable to do more than one thing at a time. The trick is to write code efficiently so it looks like several things are happening at ...
Brian Moreau's user avatar
3 votes

How can I implement double buffering with an Arduino UNO?

How can I implement double buffering with an Arduino UNO? Full screen double buffering (aka off-screen bitmap) for an ST7735 (128 x 160 x 16 bit color) would require 40 Kbyte. With only 2K byte SRAM ...
Mikael Patel's user avatar
  • 7,969
3 votes
Accepted

How to concatenate strings

You can use sprintf to format a string. You have to change: test=celcius+" deg celsius"+" "+relativeHumidity+" relative humidity"; for sprintf(test,"%d deg celsius %d relative humidity",celcius,...
Juansal's user avatar
  • 46
3 votes

How to concatenate strings

You cannot "add" character arrays like that. You may try to use a String object instead, as these do support the + operator as a way to concatenate them: String message = (String(celcius) + " deg ...
Edgar Bonet's user avatar
  • 43.3k
3 votes

7-segment display code

bitRead(x, y) takes a value x, and looks at bit number y. So, if: y is the number 2; x is 53 (binary number 0 0 1 1 0 1 0 1) ^ it looks at bit #2. Bits are ...
John Burger's user avatar
  • 1,875
3 votes

ILI9163C screen not working properly

I had the same board and problem as you, what fixed is was changing the board setting to black even though it is phyiscally red. Inside Arduino\libraries\TFT_ILI9163C\_settings\TFT_ILI9163C_settings....
pizzaisdavid's user avatar
3 votes

Adafruit 128x64 OLED not turning on

Wiring is your problem. Use soldering iron/solder and flux. Solder your wires. Intermittent connections and accidental shortages with current setup may damage your Arduino and display (and possible ...
smajli's user avatar
  • 472
3 votes
Accepted

Reading text from SD card is returning weird characters

The text file is not ASCII, it is UTF-8. You will either have to convert it to pure ASCII, or write (or obtain) a conversion routine to approximate the UTF-8 characters using ASCII on the Arduino. ...
Majenko's user avatar
  • 105k
3 votes
Accepted

How to get text to flash on ssd1306 i2c screen

As approved by the OP, the error was caused by not having reset the cursor to a visible position on the display. The text was written outside of the OLED. It seems as the clearDisplay() method does ...
Peter Paul Kiefer's user avatar
3 votes

How can I display text on OLED?

Just guessing but looks to me like you read the CAN message and print it character by character to the Serial console but you don't save those characters in a buffer as you get them from CAN.read(). ...
Richard Chambers's user avatar
3 votes
Accepted

Scroll Left to Right on MAX7219 Display

To scroll in the opposite direction, change this if statement: if( --x < len * -8 ) { x = LEDMATRIX_WIDTH; } to this: if( ++x > LEDMATRIX_WIDTH+len*8 ){ x = 0; } x (the start ...
chrisl's user avatar
  • 16.3k
3 votes
Accepted

Slow refresh rate of 1.8 TFT display

The ST7735 TFT uses SPI to communicate. That can never be particularly fast. At 160x128 pixels with 16-bit colour depth that gives you 327680 bits that you need to transfer just for the colour data. ...
Majenko's user avatar
  • 105k
3 votes
Accepted

I want a bar type display for my Arduino Project

As Majenko already stated, the second image shows a custom display. It is not pixelated, because each shown element/symbol has it's own element in the LCD. When you have one of these displays, you ...
chrisl's user avatar
  • 16.3k
3 votes
Accepted

ST7789 TFT display only shows a correct image while Arduino reset button is held down - Why?

I found the answer to this problem. After reading multiple web pages / YouTube videos from multiple authors on this device and ~all of them warning you must never connect the Vcc to 5v or it will ...
WildCat's user avatar
  • 323
3 votes
Accepted

Alternatives to Nextion display

We work with Proculus displays, and we are a distributor of this display here in Brazil (Victor Vision). The display is great, very professional. Used in medical equipments, and cheaper than Nextion. ...
Marcio Mello's user avatar
3 votes

Can this display's address be changed?

There are two different OLED screens in the links you shared. 1. OLED Display on Adafruit Link The OLED display on the Adafruit link does not have an address as it communicates via the SPI interface. ...
Sercan's user avatar
  • 131
3 votes
Accepted

LiquidCrystal issue with HD44780 display

The error is, that V0 has VDD level by the way you connected the resistors. The "lower end" of your ladder needs to be at GND, pin 1. The pin 15 (A) is the anode of the backlight, and is not ...
the busybee's user avatar
  • 2,088

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