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+--- Thread: ADS1115 reading voltage (/showthread.php?tid=5330)
ADS1115 reading voltage - SARASTRO - 2024-04-12
Trying to control battery voltage with an ADS1115, (I have OP2 version), Found this problem:
To avoid measuring signals higher than the Vin. (5V in my case), I installed a voltage divider, and really is measuring 3,3V aprox.
The problem is that se output in SignalK is "null". But is OK if we ask "raw data"
Can anybody aid me to solve this problem?
Many thanks!
RE: ADS1115 reading voltage - baltika_no_9 - 2024-04-13
It's almost impossible to read the details from photographs. Perhaps you could add a screenshot instead? Your value in electrical.batteries.SERV1.voltage.raw does that say 26859?
When you installed the ADS1115 in I2C what Range did you set?
RE: ADS1115 reading voltage - SARASTRO - 2024-04-23
I have already discovered the problem. I thought that by powering the ADS1115 at 5v, I could measure a signal up to about 5v. (The limit is VIN+0.3V) and I calculated the voltage divider accordingly.
It looks like the chip actually has a 5 to 3.3v internal step-down, so it can't actually measure signals higher than about 3.6v.
In these conditions, it was somewhat above the range (26,400) and for this reason I was getting a "null" as voltage instead of the actual measurement.
Fixed by modifying the voltage divider R values.
Thanks for the help.
RE: ADS1115 reading voltage - PaddyB - 2024-04-23
(2024-04-23, 08:02 PM)SARASTRO Wrote: I have already discovered the problem. I thought that by powering the ADS1115 at 5v, I could measure a signal up to about 5v. (The limit is VIN+0.3V) and I calculated the voltage divider accordingly.
It looks like the chip actually has a 5 to 3.3v internal step-down, so it can't actually measure signals higher than about 3.6v.
In these conditions, it was somewhat above the range (26,400) and for this reason I was getting a "null" as voltage instead of the actual measurement.
Fixed by modifying the voltage divider R values.
Thanks for the help.
The internal gain amplifier is adjustable to 2/3 & can read voltages above 3.3v though not sure if that's `possible in the openplotter setup
RE: ADS1115 reading voltage - baltika_no_9 - 2024-04-23
That's interesting, perhaps you have a different type of ADS1115. I power mine from 5V, set gain to 1 (standard in OP) so that maximum voltage it can read is 4.096V and it works fine.