EEPROM command kills my LCD-display!

[zap-zarrap]

I dont know if it is the right place to put my issue here, because its a bit complicated, so sorry for that if its so.

i created my own arduino nano low power version. see pic
if any one is interested in the EAGLE FILE, i will upload it.

the board is working fine so far. the code (relevant parts shown) used is already tested before with standard arduino nano. no problems so far. in short, i first upload a sketch via USB where i write 2 float variables in to the EEPROM. after that i upload a sketch where it reads the floats from EEPROM and saves them to the variables Min and Max. and then i display the values on the LCD(with I2c). in standard opperation of the device i need to change these values by buttons and then save them to EEPROM again for use after reboot.

Now here is the Problem:
If i Upload the code via ISP-Programmer AVRISP MKII to my custom arduino the LCD freezes with black bars forever (ireversible, even if i upload a working sketch) and the arduino freezes too, i cant even reset the atmega. if i delete the EEPROM lines in the sketch, remove the lcd and upload to the same arduino and replace to a new LCD Display, it is working again. i am using an ATMEGA 328PB on my custom arduino. i destroyed 2 lcd until i found the problem. i have no clue whats going on here and i am not very experienced in programming. if anyone has an idea i would be very thankful!

"
#include "HX711.h" // GitHub - bogde/HX711: An Arduino library to interface the Avia Semiconductor HX711 24-Bit Analog-to-Digital Converter (ADC) for Weight Scales.
#include "Wire.h"
#include <LiquidCrystal_I2C.h> // GitHub - johnrickman/LiquidCrystal_I2C: LiquidCrystal Arduino library for the DFRobot I2C LCD displays
#include "math.h"
#include <ButtonDebounce.h>
//#include <EEPROM.h>
#include "LowPower.h"

float Min = -5.0;
float Max = -3.0;

//float Min = EEPROM.get(0, f);
//float Max = EEPROM.get(4, f);

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
// Serial.begin(115200);

// float Min = -5.0;
// float Max = -3.0;
// EEPROM.put(0,Min);
// EEPROM.put(4,Max);

lcd.init(); //Im Setup wird der LCD gestartet
lcd.backlight(); //Hintergrundbeleuchtung einschalten (0 schaltet die Beleuchtung aus).

lcd.setCursor(0, 0);
lcd.print(" ");
lcd.setCursor(7, 0);
lcd.print(">Min=");
lcd.print(Min, 1);
lcd.setCursor(7, 1);
lcd.print(" Max=");
lcd.print(Max, 1);
"

[anon73444976]

Your code is incomplete.

Please remember to use code tags when posting code

[zap-zarrap]

I forgot to say, that i am using minicore with the internal clock 8mhz.

i found out now, that the compiler overrides the eeprom upon uploading code, so it states "nan" at the serial monitor for the value of the float Min. so i am sending some kind of strange bit sequence to the lcd-i2c converter, possibly damaging the operating system of the i2c module?!

@themember....
how do i use code tags?

[anon73444976]

zap-zarrap:
I forgot to say, that i am using minicore with the internal clock 8mhz.

sp. "8MHz"

i found out now, that the compiler overrides the eeprom upon uploading code

It does? The compiler doesn't upload code...

@themember....
how do i use code tags?

Like this [code][/code] (It's the </>" icon on the toolbar)

[WattsThat]

You do not destroy lcd’s with incorrect code. You are perhaps using incorrect settings for your crystal or other issues with the clock source. It would be a good idea to post the board schematic in pdf format.

Please code all of your code, with code tags.

nan means “not a number” which means you’re reading an invalid floating point number which happens when reading the wrong address.

[cattledog]

@zap-zarrap

in short, i first upload a sketch via USB where i write 2 float variables in to the EEPROM. after that i upload a sketch where it reads the floats from EEPROM and saves them to the variables Min and Max. and then i display the values on the LCD(with I2c). in standard opperation of the device i need to change these values by buttons and then save them to EEPROM again for use after reboot.

Now here is the Problem: If i Upload the code via ISP-Programmer AVRISP MKII to my custom arduino the LCD freezes with black bars forever (ireversible, even if i upload a working sketch) and the arduino freezes too, i cant even reset the atmega

It sounds like you have incorrect fuse settings when loading with the ISP.

[zap-zarrap]

Thank you for your help i solved this Problem by setting the Fuses and then the eeprom retains and the data send to the lcd is Not nan anymore. But noch ive got a similar Problem. I will open a New Topic. Its so strange....