3 ms·

Could have been simpler still. You can read the internal temperature of the ATiny85 [1]. You can also get the ATiny85 to speak USB and even be flashed via USB v

by bArray 1y ago

Could have been simpler still. You can read the internal temperature of the ATiny85 [1]. You can also get the ATiny85 to speak USB and even be flashed via USB via the micronucleus bootloader [2]. [1] https://andrey.mikhalchuk.com/2011/06/20/reading-attiny854525-internal-temperature-sensor.html https://andrey.mikhalchuk.com/2011/06/20/reading-attiny85452... [2] https://github.com/micronucleus/micronucleus https://github.com/micronucleus/micronucleus

MisterTea 1y ago
How does the internal temperature sensor help here?
- gosub100 1y ago
  I think he means tape/glue it to the heat source to (mis)-use it as a probe. "It's not stupid if it works" but I think there would need to be a few deg of compensation to account for the thermal resistance of the package.
  - MisterTea 1y ago
    Then you have the problem of the PCB getting in the way.
    - numpad0 1y ago
      The author has an I2C temp sensor next to a giant MOSFET. The author also uses clearly ChatGPT generated avatar and mentions I2C is bit banged yet completely left out circuit schematics which incidentally includes freewheel diode for the fan. PCB getting in the way isn't going to matter in this instance.
      - bArray 1y ago
        > The author has an I2C temp sensor next to a giant MOSFET. Yeah... It's either overkill, or there is some decent power going through it and it will affect thermal measurements anyway. Not to mention what it might do to the reference voltage. > [..] mentions I2C is bit banged [..] They possibly bit banged it? But it wouldn't have been needed given the hardware support... > [..] yet completely left out circuit schematics [..] Yeah, which is far more important that anything else. > [..] which incidentally includes freewheel diode for the fan. This may have been sensible to be fair, especially if you happen to rapidly change the delta PWM signal, you could end up with a decently sized back-EMF. But I think even better would be to sink it into something, rather than back into the power supply of sensitive components... > PCB getting in the way isn't going to matter in this instance. Agreed.
  - bArray 1y ago
    Doesn't even need to be attached to the heat source, just thermally coupled. Could be achieved for example via a short, fat, insulated, shared ground plane or something. The compensation might be needed, and the internal thermal sensor also needs tuning in any case if you read the specs, but it's close enough that you could use it out of the box and only be out by a few degrees. Chip temperature with regular sleeps isn't going to be a significant factor. There is enough code space on the ATtiny85 that you could actually build a model that takes measured temperature T at time t (T_t), the goal temperature of G (G_t) and produce a predictive model for M(T_t, G_t) = T_{t+n}. You could then do something a little smarter than a PID controller that takes in some profile considerations, i.e. slow (low noise, low RPM, likely for normal usage), fast (high noise, high RPM in bursts, likely for gaming).
ashafq 1y ago
I did try the internal temperature sensor, but it didn't measure the ambient temperature. I have read that if you set the ATtiny85 to sleep mode for some time, it will converge to ambient temperature, but it would take too long to validate, and I didn't want to go down another rabbit hole. USB Bootloader is interesting, but I already had a few ISP loaders. You can make an ISP loader with Arduino as well. [1] [1] https://docs.arduino.cc/built-in-examples/arduino-isp/ArduinoISP/ https://docs.arduino.cc/built-in-examples/arduino-isp/Arduin...
- bArray 1y ago
  > I did try the internal temperature sensor, but it didn't measure the ambient temperature. I have read that if you set the ATtiny85 to sleep mode for some time, it will converge to ambient temperature, but it would take too long to validate, and I didn't want to go down another rabbit hole. It's kind of better than ambient, it would reach the temperature of the GPU if thermally coupled. The sleep-mode thing would just be a case of lots of micro sleeps to discount the temperature of the chip, could have even under-clocked too. > USB Bootloader is interesting, but I already had a few ISP loaders. You can make an ISP loader with Arduino as well. The benefit of USB is being able to get debug data from the fan controller as it runs, and be able to re-flash it whilst in the PC by attached to an internal USB bus. This way you could also log out what the GPU reports, vs what you measure, vs what the ATtiny85 measures.

by bArray 1y ago

MisterTea 1y ago

How does the internal temperature sensor help here?

gosub100 1y ago
I think he means tape/glue it to the heat source to (mis)-use it as a probe. "It's not stupid if it works" but I think there would need to be a few deg of compensation to account for the thermal resistance of the package.
- MisterTea 1y ago
  Then you have the problem of the PCB getting in the way.
  - numpad0 1y ago
    The author has an I2C temp sensor next to a giant MOSFET. The author also uses clearly ChatGPT generated avatar and mentions I2C is bit banged yet completely left out circuit schematics which incidentally includes freewheel diode for the fan. PCB getting in the way isn't going to matter in this instance.
    - bArray 1y ago
      > The author has an I2C temp sensor next to a giant MOSFET. Yeah... It's either overkill, or there is some decent power going through it and it will affect thermal measurements anyway. Not to mention what it might do to the reference voltage. > [..] mentions I2C is bit banged [..] They possibly bit banged it? But it wouldn't have been needed given the hardware support... > [..] yet completely left out circuit schematics [..] Yeah, which is far more important that anything else. > [..] which incidentally includes freewheel diode for the fan. This may have been sensible to be fair, especially if you happen to rapidly change the delta PWM signal, you could end up with a decently sized back-EMF. But I think even better would be to sink it into something, rather than back into the power supply of sensitive components... > PCB getting in the way isn't going to matter in this instance. Agreed.
- bArray 1y ago
  Doesn't even need to be attached to the heat source, just thermally coupled. Could be achieved for example via a short, fat, insulated, shared ground plane or something. The compensation might be needed, and the internal thermal sensor also needs tuning in any case if you read the specs, but it's close enough that you could use it out of the box and only be out by a few degrees. Chip temperature with regular sleeps isn't going to be a significant factor. There is enough code space on the ATtiny85 that you could actually build a model that takes measured temperature T at time t (T_t), the goal temperature of G (G_t) and produce a predictive model for M(T_t, G_t) = T_{t+n}. You could then do something a little smarter than a PID controller that takes in some profile considerations, i.e. slow (low noise, low RPM, likely for normal usage), fast (high noise, high RPM in bursts, likely for gaming).

ashafq 1y ago

I did try the internal temperature sensor, but it didn't measure the ambient temperature. I have read that if you set the ATtiny85 to sleep mode for some time, it will converge to ambient temperature, but it would take too long to validate, and I didn't want to go down another rabbit hole. USB Bootloader is interesting, but I already had a few ISP loaders. You can make an ISP loader with Arduino as well. [1] [1] https://docs.arduino.cc/built-in-examples/arduino-isp/ArduinoISP/ https://docs.arduino.cc/built-in-examples/arduino-isp/Arduin...

bArray 1y ago
> I did try the internal temperature sensor, but it didn't measure the ambient temperature. I have read that if you set the ATtiny85 to sleep mode for some time, it will converge to ambient temperature, but it would take too long to validate, and I didn't want to go down another rabbit hole. It's kind of better than ambient, it would reach the temperature of the GPU if thermally coupled. The sleep-mode thing would just be a case of lots of micro sleeps to discount the temperature of the chip, could have even under-clocked too. > USB Bootloader is interesting, but I already had a few ISP loaders. You can make an ISP loader with Arduino as well. The benefit of USB is being able to get debug data from the fan controller as it runs, and be able to re-flash it whilst in the PC by attached to an internal USB bus. This way you could also log out what the GPU reports, vs what you measure, vs what the ATtiny85 measures.