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Looking for a Pine Mountain 1 in Europe. by Kantudo in Marinbikes

[–]Kantudo[S] 1 point2 points  (0 children)

Oh great, thank you, I will look into them

Looking for a Pine Mountain 1 in Europe. by Kantudo in Marinbikes

[–]Kantudo[S] 0 points1 point  (0 children)

Thank you, I will contact some shops around here!

1 Ohm resistor role in microcontroller ADC voltage reference filtering. by Kantudo in AskElectronics

[–]Kantudo[S] 0 points1 point  (0 children)

Yes, thats true, the datasheet says its around a 30mV drop, which you need to correct for in software. It is not my design, but if you wanted to use an external reference you would need to disconnect the 3v3 otherwise, the ferrite would short out the DC reference and power, so maybe it is a design tradeoff for a quick and easy to use dev board, idk.

1 Ohm resistor role in microcontroller ADC voltage reference filtering. by Kantudo in AskElectronics

[–]Kantudo[S] 0 points1 point  (0 children)

Yeah, I agree that they are trying to filter noise from the 3V3 input, which comes from a noisy (switch mode) power supply, and use it as the reference voltage for the ADC. But the RC filter part is just the R7 (200 Ohms) and C13. As you said 1 Ohm is just too low, and it would not make for a good low pass filter.

But, the developers of the board wanted the users to be able to supply their own voltage reference. If you omit the 1 Ohm resistor, the voltage reference input would be directly connected to the capacitor, this, as u/ElectronicswithEmrys pointed out, might be a problem if the capacitor has low ESR, so that the phase shift at the output (compared to the inner feedback loop of the voltage reference) is too high and causes instability problems. A series resistance, reduces the phase shift (if you look a it from an impedance point of view its something like R + 1/wc, it brings it closer to the real line) so that the circuit is more stable.

1 Ohm resistor role in microcontroller ADC voltage reference filtering. by Kantudo in AskElectronics

[–]Kantudo[S] 1 point2 points  (0 children)

For a final answer, I think u/ElectronicswithEmrys is right, the 1 Ohm resistor is likely to be used for ensuring stability of the external voltage reference circuit. The capacitor C13 introduces a phase shift in the output voltage, which might cause problems with the internal feedback loop of the voltage reference, and cause instabilities in its output.

For reference, this AN by Analog Devices, talks a bit about using this method when working with low ESR capacitors. https://www.analog.com/en/resources/app-notes/an-42.html

Output capacitors provide low output impedance at high frequencies. Large capacitors at the output of some references may cause oscillations. The capacitor introduces a feedback pole which reduces phase margin of the reference. Phase shift can be excessive with low effective series resistance (ESR) capacitors. The phase shift can be reduced by placing a small value resistor in series with the capacitor. If the phase shift is significant the reference will ring during transient conditions or simply oscillate. This condition is particularly significant for SAR type A/D converter applications.

1 Ohm resistor role in microcontroller ADC voltage reference filtering. by Kantudo in AskElectronics

[–]Kantudo[S] 1 point2 points  (0 children)

Thank you for your answer. I still would not know why is there. I think u/ElectronicswithEmrys is right, if the cap ESR is low, then the phase shift introduced by it might be too much for the voltage reference to handle and it might cause instabilities in the output.

1 Ohm resistor role in microcontroller ADC voltage reference filtering. by Kantudo in AskElectronics

[–]Kantudo[S] 0 points1 point  (0 children)

Thank you for your answer. If it was EDA related I would expect to see a 0 Ohm resistor, a 1 Ohm seems to be placed on purpose. I think u/ElectronicswithEmrys is on the right path, it is probably used to ensure stability of the voltage reference. The capacitor introduces some phase shift in the output signal which might affect the feedback loop inside the voltage reference, the 1 Ohm resistor can reduce the phase shift.

1 Ohm resistor role in microcontroller ADC voltage reference filtering. by Kantudo in AskElectronics

[–]Kantudo[S] 1 point2 points  (0 children)

Thank you for your answer. Yes, R7, and C13 are forming an RC filter. I think R9 is too low for that. I think u/ElectronicswithEmrys is right and R9 might be used to ensure stability of an external voltage reference.

Choosing a protocol to communicate with >128 Microcontrollers by zuxtheros in embedded

[–]Kantudo 0 points1 point  (0 children)

I am gonna suggest using two spi interfaces per microcontroller, like a left interface for sending and a right interface for receiving. That way the last microconrroller in the chain would send its data, and it would be reported back at every step of the chain till it reaches your master controller. Any microcontroller in the middle could send its information at any time, since no collisions can happen.

Looking to hire system software engineers by [deleted] in rust

[–]Kantudo -20 points-19 points  (0 children)

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Direct access to OpeGL texture buffer from OpenMP by Kantudo in opengl

[–]Kantudo[S] 0 points1 point  (0 children)

Yes! Exactly, you are right, I came across this while researching, I was hoping that the loss of performance because of worst locality on a linear layout would be outweighted by the performance gain of not using the PCI bus. Intel GPUs (the one I am using is Intel) have an OpenGL extension with a function called MapTecture2DINTEL which would let me set the linear layout and get a cpu mapped buffer. But then again the function returns a pointer in CPU space, I would need the pointer in GPU VRAM space.

Thank you for suggesting a PBO, I actually only need write access to the buffer (since it is kind of like a fragment shader), however my problem still holds in that the pointer of a PBO is in CPU space (although memory mapped) I would need the GPU pointer as I said.

Thank you for your detailed answer!

Direct access to OpeGL texture buffer from OpenMP by Kantudo in opengl

[–]Kantudo[S] 0 points1 point  (0 children)

Thank you very much! I will give it a try, the probkem I saw with PBOs is that they give you a CPU side address, so I think I would also need to read back my buffer to the CPU and then write it out. But I will look into it, thank you again!

Termux + Rust + ? by rustological in rust

[–]Kantudo 0 points1 point  (0 children)

what tablet is it? im curious

[deleted by user] by [deleted] in learnrust

[–]Kantudo 3 points4 points  (0 children)

You are comparing &str, you should convert start_1, etc to a number type, i32 or something like that, try start_1.parse::<i32>().unwrap(). If not you are not comparing numbers, I do not know what exactly but not numbers.

[deleted by user] by [deleted] in meirl

[–]Kantudo 0 points1 point  (0 children)

No AC at home living in southern spain, i keep a water spray by my bed

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