+- Robo-Tank DIY Aquarium Controller Forum (https://www.robo-tank.ca/forum)
+-- Forum: Robo-Tank (https://www.robo-tank.ca/forum/forum-1.html)
+--- Forum: Reef-pi Software Questions (https://www.robo-tank.ca/forum/forum-5.html)
+--- Thread: Confusion with I2C addresses (/thread-1192.html)
Confusion with I2C addresses - JFReyes - 02-09-2021
Hi:
I just received the PCA9685 expander but am confused about I2C addresses. With nothing attached to my controller board shows addresses 40, 63 & 70 as present in i2cdetect. Addresses 40 & 70 also appear on my Pi4 which is standalone and not connected to anything; therefore I reckon they are built in to the Pi circuitry for some purpose.
Apparently address 63 belongs to the Reef-Tank controller's built in PCA9685 circuit, although the Reef-Tank manual says it should be configured as address 64. Perhaps that explains why I couldn't get the RS232 custom cable to work with the Power Bar.
When I connect the expander it shows up as address 50.
Could you confirm the correct I2C addresses for both the built in and expander PCA9685 circuits? How should the expander driver be configured?
Thanks for the help.
RE: Confusion with I2C addresses - Rob F - 02-09-2021
Ah yes those confusing addresses. The reason for the confusion is i2cdetect shows hex values for addresses but reef-pi and most documents talk regular decimal number. I always thought it was an addressing issue for that custom cable because it should have worked.
Address 0x63 = 99 in reef-pi driver, this is the pH circuit.
Address 0x40 = 64 in reef-pi driver, this is the onboard pca9685
Address 0x70 = 112 in reef-pi driver, this is also for pca9685. That address will control all pca9685 in the circuit.
Address 0x50 = 80 in reef-pi driver, this is the expansion.
Here's a calculator for addresses.
https://www.rapidtables.com/convert/number/hex-to-decimal.html?x=0x50
RE: Confusion with I2C addresses - JFReyes - 02-10-2021
(02-09-2021, 07:58 PM)Rob F Wrote: Ah yes those confusing addresses. The reason for the confusion is i2cdetect shows hex values for addresses but reef-pi and most documents talk regular decimal number. I always thought it was an addressing issue for that custom cable because it should have worked.
Address 0x63 = 99 in reef-pi driver, this is the pH circuit.
Address 0x40 = 64 in reef-pi driver, this is the onboard pca9685
Address 0x70 = 112 in reef-pi driver, this is also for pca9685. That address will control all pca9685 in the circuit.
Address 0x50 = 80 in reef-pi driver, this is the expansion.
Here's a calculator for addresses.
https://www.rapidtables.com/convert/number/hex-to-decimal.html?x=0x50
Thank you for the explanation, Rob!
RE: Confusion with I2C addresses - Rob F - 02-10-2021
(02-10-2021, 02:10 AM)JFReyes Wrote:(02-09-2021, 07:58 PM)Rob F Wrote: Ah yes those confusing addresses. The reason for the confusion is i2cdetect shows hex values for addresses but reef-pi and most documents talk regular decimal number. I always thought it was an addressing issue for that custom cable because it should have worked.
Address 0x63 = 99 in reef-pi driver, this is the pH circuit.
Address 0x40 = 64 in reef-pi driver, this is the onboard pca9685
Address 0x70 = 112 in reef-pi driver, this is also for pca9685. That address will control all pca9685 in the circuit.
Address 0x50 = 80 in reef-pi driver, this is the expansion.
Here's a calculator for addresses.
https://www.rapidtables.com/convert/number/hex-to-decimal.html?x=0x50
Thank you for the explanation, Rob!
No problem!
RE: Confusion with I2C addresses - JFReyes - 02-10-2021
Hi again:
Just tried setting up the PCA9685 expander connected to a Power Bar without success, as no relays clicked. I'll try again using some measuring instruments I have but it would be useful to have proper documentation.
Thanks,
RE: Confusion with I2C addresses - Rob F - 02-10-2021
Sorry I don't have a manual yet, do you see the I2C address?
Can you post pics of the driver and connectors you added?