| PWM Val | 0 | 250 | 500 | 750 | 1000 | 1100 | 1200 | 1300 | 1400 | 1500 | 1600 | 1700 | 1800 | 1900 | 2000 | 2020 | 2040 | 2041 | 2042 | 2043 | 2044 | 2045 | 2050 | 2100 | 4095 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Voltage | 12 | 11.86 | 11.33 | 10.58 | 9.27 | 8.84 | 8.26 | 7.67 | 7.09 | 6.51 | 5.92 | 5.35 | 4.79 | 4.21 | 3.7 | 3.6 | 2.84 | 2.47 | 1.56 | 0.45 | 0.05 | 0.002 | 0 | 0 | 0 |
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Thanks Nate for documenting. Will be curious to see why this is happening. Can you measure the voltage coming into the transistor (see schematic below, pin 1) to see if that that is from the TLC5940 chip or the transistor?
Measuring pin1 to pin2 of the transistor (gate to ground)
| PWM Val | 0 | 1000 | 1500 | 4095 |
|---|---|---|---|---|
| Voltage | 3.3 | 1.65 | 0.85 | 0 |
So this means that it’s the Tlc5940 itself right? Because the voltage I measured using the multimeter shouldn’t drop that quickly
Tagging @ezirayw. We’ve talked about this in the past. Ezira has o-scope traces coming off the Tlc at various input values.
I didn’t save the traces since I decided to ditch using intermediate PWM value. But if I remember correctly, the PWM duty cycle didn’t reflect what you’d expect given a certain Tlc input on the arduino, which lead to the voltages not being correct. I think it has to do with how the Tlc library is designed to communicate with the chip because the datasheet indicates that it should be proportional.
https://www.ti.com/lit/ds/symlink/tlc5940.pdf?ts=1643314201710 (page 20)
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It might be worth looking into the library and checking to see if arduino inputs are communicated properly
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Hello, there!
Did you figure out what was the issue? I’m having the same problem
Hey Eduarda! Sorry this has yet to be a critical issue for us, so no one has gone through the libraries to figure out the fix.
Hey @danhart if you’re talking to the EDF anyway, any chance you can get them to fix this?
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