Having some trouble with I2C MCP4725

hey Folks having some issues with


It works fine with just one Sparkfun MCP4725 Breakout but when I add a second one with the A0 pin going to High and resistors removed it stops working entirely.

both work Fine on their own with their own addresses set to 0x60 and 0x61 but not together…

mcp4725-throttle-test.xodball (3.9 KB)

When you say “resistors removed”, is that resistors on I2C pins? Did you remove them from both boards, or just the board in the middle of the I2C chain? If resistors are needed for single board, they will still be needed on the last board in the I2C chain.

correct Resistors were removed from the I2C on one board, does the board with the resistors have to be physically at the end of the circuit?

Hi, I really don’t know if this can work, but you could try


Yes, resistors should be at the end of the circuit.

Ok, So the Defer works, But it seems I have some possible noise as the signals are not consistent.

the MCP4725 Nodes flash red every so often.

I added 330ohm resistors in series between the 2 breakout boards on the SDA and SCL lines and it seems to have calmed it down abit but its not nearly as responsive as i was hoping it would be

MCP4725 nodes update when VAL changes.

But when both are at A1, both use the bus at the same time and it is blocked, so the defer delays one node.

Now A0 and A2 readings are in loop, it could update every a set time.

Can also set a time to A1, instead of a loop, you can use clock or throttle node.

Thanks a bunch! the Clock Node on A1 cleared everything up immediately! I guess it was sampling too fast.

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