Printing numbers and letters to I2C LCD using serial communication

Question

N/A 2019-8-6

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/475151-printing-numbers-and-letters-to-i2c-lcd-using-serial-communication

评论： MathWorks MATLAB Hardware Team 2023-12-11

Hi everyone,

I'm currently using an Arduino Uno with a I2C LCD hooked up to it. I've browsed through a bunch of the posts and have tried numerous strategies to get my I2C display to display numbers and a string. Anything I output is just giving me whole numbers like 100, 101, 110 etc. I'm not getting any text at all. What I would like it to display on my LCD Screen is "Heart Rate: 79.95"

Here is what I have:

arduino=serial('/dev/tty.usbmodem14101','BaudRate',9600);

fopen(arduino);

heartrate=79.95;

fprintf(arduino,'Heart Rate: %d\n',heartrate);

fclose(arduino);

I've varied fprintf (ex: fprintf(arduino,'%.2f',heartrate)) to just print a decimal number and it also won't do it, I still get whole numbers.

Any ideas?

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Answer 1

N/A 2019-8-8

0
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https://ww2.mathworks.cn/matlabcentral/answers/475151-printing-numbers-and-letters-to-i2c-lcd-using-serial-communication#answer_386856

I ended up solving my problem. For future reference, if you are trying to use an I2C LCD with Arduino there's a couple of steps you have to follow.

Install Matlab Arduino Hardware Support Packages
Install Arduino IDE
Find the correct port for your device on Windows (COM) or Mac (/dev/tty or /dev/cu)
Install LiquidCrystal_I2C and find your I2C address
Read the thread by Robin2 and use the code that matches your needs
Search for fprintf_r and install in Matlab directory
This snippet of code sends the heartrate to Arduino IDE

calculated_HR = 79.95;

heartrate=num2str(calculated_HR);

fprintf(arduino,heartrate);

fprintf_r('reset');

Two things to note: First, it's really important to convert your double to a string since Arduino will be receiving it as an array of characters. Second, fprintf_r is needed because it basically sends a carriage end to Arduino to signify that's the end of the transmission.

Hope this helps.