(SOLVED) Strange behavior of devices on a bus i2C

Other Hardware Displays
1

Hello,

I don't know if this is the best board to talk about the problem I meet.
I have the following devices on an I2C bus:

When I put the RTC board and launch the Nick Gammon scanner I see the RTC and the eeprom.
If I add the light sensor, I see the three.
But if I add the LCD, I see all devices but the eeprom which completely disappear.

Any idea ?
Should I post this question on the protocoles/devices board ?

Thanks in advance

nbenm

2

So, with Nicks scanner you can see three I2C addresses, but not four.
How about if you only hook up the LCD, and none of the others, can you see it?

3

jackwp:
So, with Nicks scanner you can see three I2C addresses, but not four.
How about if you only hook up the LCD, and none of the others, can you see it?

I can see Three addresses in spite of four.
If I remove only the LCD, all is OK
With RTC, eeprom and LCD, I see only RTC and LCD.
If I leave the LCD alone, I see 0x27 which is correct.

It looks like when I add LCD eeprom only goes away

Sometimes, in very rare cases, I see the four.

Btw, I have inverted eeprom and rtc addresses. It should be 0x68 RTC and 0x50 EEPROM

4

Could it be the voltage on the wire? When 2 or 3 are connected, ok, but by 4 to much load?
Do you have a pullup resistor on both lines? About 2K?

5

jackwp:
Could it be the voltage on the wire? When 2 or 3 are connected, ok, but by 4 to much load?
Do you have a pullup resistor on both lines? About 2K?

Good one!
I was using a pc usb port as power. I use now an external source and all is ok.
I've tried many many resets, but all is ok.

Many thanks to both