July 21, 2021
General notes:
used a Rev 3.0 PD assembled as rear
used a 12V nocuta fan
used an electronic load as a substitute for horn (set to 3 ohms)
firmware: power_distribution from pd_smoketest branch
two separate power supplies (one for PD, one for UV cutoff)
U2 IS NOT POPULATED CURRENTLY
Testing Fan and Horn
First I tested the horn with a power supply; I simply soldered two wires to both terminals (I’m pretty sure the horn is not polarized) and I set a power supply for 12V with a 5.0A limit.
Once I powered on the power supply, the horn didn’t make any noise. So I turned of the supply and incremented the current limit by 1A. I repeated this process until I got to 9A which was when the horn started blasting very loudly (be prepared to turn it off). I then turned on the supply again and waited for about 3 seconds to see the current draw of the horn, which was about 4.7A → the horn has an inrush of 9A and then it will draw 4.7A.
You can try taping the opening of the horn to reduce the sound, but it will still be very loud and it may vibrate as well.
So instead of continuing to use the horn to test UV cutoff, I used an electronic load set to 3 ohms
(13.5V / 4.7A ≈ 3 ohms).
After connecting the electronic load to the horn terminal block, I connected the fan to one of the fan connectors.
I flashed a controller board with power_distribution from the pd_smoketest branch and placed in onto a rear, Rev 3.0 PD (firmware accounts for rear and front). I connected the board together through the 6 interfacing wires (see P6 on UV cutoff, and see UV Cutoff Interface on PD).
I first powered on PD (with 13.5V), and then UV cutoff (with 13.5V) using separate power supplies. The fan should spin and you should see something like this from the electronic load:
I then powered off UV cutoff and plugged in the fan into a different plug; I did this until I confirmed that all fan connectors work.
Testing UV lockout/cutoff function
I first powered PD with 13.5V, and then I powered UV cutoff (connected with a fan and an electronic load set to 3 ohms) with 13.5V using separate power supplies.
I first decremented the voltage for UV cutoff by 1V. I found out that the board “locks out/cuts off” at 8.5V (the fan stopped spinning and the voltage of the electronic load dropped to zero). When I decremented the voltage at 7.5V, I got a message through minicom that said “UV lockout was triggered”.
I then incremented (by 1V) and the fan started spinning once the voltage reached 10.5V (and the voltage of the electronic load went up to ~10.476V).
Now I decided to decrement the voltage for UV cutoff by 0.1V (starting at 13.5V). I found out that the board “locks out/cuts off” at 8.7V (the fan stopped spinning and the voltage of the electronic loaddropped to zero). When I decremented the voltage to 7.8V, that’s when I got the “UV lockout was triggered” message.
I then incremented (by 0.1V) and the fan started spinning once the voltage reached 10.2V (and the voltage of the electronic load went up to ~10.176V).
Voltage readings (IGNORE):
UV cutoff is turned on (power supply draws ~4.29V):
VBAT_I_SENSE: 3.2725V
FAN_I_SENSE: 0.1678V
HORN_I_SENSE: 0.2575V
UV cutoff is turned off
VBAT_I_SENSE: 3.2840V
FAN_I_SENSE: 0.0004
HORN_I_SENSE: 0.0002V