Size of EEPROM changed

Firmware
1

Upgraded to firmware 5.0. I noticed in the reference docs that the size of the emulated EEPROM has changed from 2048 to 2047 bytes for the Photon. I tried testing this by writing and reading values and discovered that the size of the EEPROM is actually 2043 bytes. Verified this finding on 2 Photons. Can anyone else confirm this?

2

The eeprom emulation was recently rewritten by @jvanier to be more robust and testable - I’ll leave it to him to comment on any size changes.

3

The EEPROM now has 2047 addressable bytes on the Photon. Can you tell me more details on how you calculate 2043?

4

@jvanier
Hi Julien, I arrived at that conclusion, maybe too quickly, because I’m unable to put and get different values to addresses 2044-2047. They always return the same value.

5

@jvanier
I’ve also just encountered a new EEPROM problem now with a Photon. After a red SOS (didn’t manage to count the number of blinks), I’m now unable to write new values to certain EEPROM addresses. When I try to write to address 2043 after power up, the Photon will attempt to store a new value to that address, but when I try to retrieve that data with a get command, the Photon will not respond. All I’m trying to do with that 2043 location is store a bool variable that when equal to 1, will perform certain tasks. As is with this Photon in question, I’m unable to write a value of 1 to this location. This worries me quite a bit since I rely very heavily upon the EEPROM in several permanent installations.
I’ll also mention that after the red SOS event, all of the data written to the EEPROM was lost.

6

Could you please save the current state of eeprom so that we can investigate the issue.

You can do this by running:

dfu-util -d 2b04:d006 -a 0 -s 0x80C000:0x14000 -U eeprom.bin

Thanks :smile:

7

Can you try the test program below? It does EEPROM.put to offsets 2040 to 2050 and then does EEPROM.get to the same offsets.

#include "application.h"

void setup() {
  for(uint8_t i = 0; i < 10; i++) {
    EEPROM.put(2040 + i, i);
  }

  String s;
  for(uint8_t i = 0; i < 10; i++) {
    uint8_t c;
    EEPROM.get(2040 + i, c);
    s += String(c, DEC) + " ";
  }
  Particle.publish("eeprom_bytes", s);
}

Then run particle subscribe mine
You should see that offsets 2040 to 2046 return the value written. 2047 and later EEPROM offsets will always return 255 (erased bytes).

{"name":"eeprom_bytes","data":"0 1 2 3 4 5 6 255 255 255 ","ttl":"60","published_at":"2016-04-25T13:43:09.603Z","coreid":"xxxxxxxxxxx"}