EEPROM in a library

Projects Programming
1

Naively I have tried to use EEPROM in a library I'm writing.

EEPROM.read always returns 0, even though I can read the same memory address from setup and echo out the real, non zero, value.

Apart from including #include <EEPROM.h> into the library file, what else is required ?

(I'm using an Uno R4 Minima )

2

Please show a sketch that demonstrates the issue. To my knowledge the Uno R4 series does not have EEPROM.

3

Tutorial on using the EEPROM: https://docs.arduino.cc/tutorials/uno-r4-minima/eeprom/

4

I'll post a simplified sketch in a minute. In the meantime there is 8kB of Flash emulated EEPROM on the RA4M1 chip used as the mcu.

Description
The Arduino® UNO R4 Minima is the first UNO board to feature a 32-bit microcontroller. It features a RA4M1 series microcontroller from Renesas (R7FA4M1AB3CFM#AA0), which embeds a 48 MHz Arm® Cortex®-M4 microprocessor. The UNO R4 Minima's memory is larger than its predecessors, with 256 kB flash, 32 kB SRAM and 8 kB data memory (EEPROM).

5

Yes that works. I am writing a separate library to control a CAN bus. I have written some values to the EEPROM and can read them back via the Setup function.
However if I read the same address space in my library it is zero.

I will post a simplified example ... soon.

6

Then there are errors in your code. For help, please read and follow the instructions in the "How to get the best out of this forum" post.

7

Here is the sample I have prepared. Please help me isolate the errors in my code.
EEPROM_test.zip (1.3 KB)

8

I've just uploaded a simple example.

9

I think I have found the issue ....

my declaration of the class instance should be

VelbusNode* node;

and then I need to create the instance

 node = new VelbusNode();

outputs

16:19:44.764 -> initialising EEPROM
16:19:44.764 -> reset local var, should be 0
16:19:44.764 -> 0
16:19:44.764 -> Read from EEPROM, should be 1
16:19:44.764 -> 1
16:19:44.764 -> Read from node, should be 1, not 0xFF
16:19:44.764 -> 1
16:19:44.764 -> write other node member value, should be 0x10
16:19:44.764 -> 16

You don't learn if you don't make mistakes !

10

I've figured it out now. I did not realise I was on SO.
Apparently some on this forum have forgotten the original ethos of Arduino.
https://www.google.com/search?channel=fs&client=ubuntu&q=arduino+purpose

11

What in the current discussion force you to think that?

12

Glad you found the errors!

13

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