I am working on a project that I need 5v power, but I need this power to be regulated based on a pulse of 25 times per second/duty cycle of .9. Is there any way I can do this without an additional transistor to modulate the straight SYS_5V source? Can I use VDD_5V as a PWD? Thanks (I’m a bit new to the hardware side of electronics, mainly a programmer)
not quite sure what you’re asking. if yo want 5v regulated power you already have it. if you want a voltage proportionate to the pwm frequency that’s another matter. if you want to output a rectangular waveform with an amplitude of 5v and 90% duty cycle, there are chips that sit on the i2c or spi busses that can do that, the pru can likely do that for you easily, or as slow as it is yo can likely do it in software bit banging a gpio with relitive accuracy. what is it you want to do?
The issue is I can only get 3.3V, even using pins P9_5, P9_6, P9_7, and P9_8.
And when I test the voltage from pin P9_5 to the ground, I don’t get anything. I rescind my statement about P9_7/8 though, but they are helpful.
The CPU on BBB is powered by 3V3. This means all digital output (GPIO, PWM, …) will be at 3V3 as well.
In order to get a 5V pulse train, you’ll need an external driver. I use darlington arrays for that purpose, like ULN2804.
BR
Thanks, so it basically seems there is not a way of getting a pulse of 5V without using a transistor. Oh well.
Thanks, so it basically seems there is not a way of getting a pulse of 5V
without using a transistor. Oh well.
The I/O on a 3.3 volt processor goes between 0 and 3.3 volts. To get
any other (larger) voltage, you'll need at least a transistor.
Harvey
Depending on exactly what is needed (current draw, etc), there is a way to
generate a 5V pulse without a transistor. I didn't see any specs on what is
needed in this thread so be sure to verify what you are doing against the
specs of all the components involved.
The VBUS line on the USB host side does have a control on there already. There
should be some debug control on the USB block.
Look, I’m no EE, but do things the right way . . . if you start putting too much current or voltage on the wrong pins. You’ll end up frying the processor. Then no doubt start telling the BBB is garbage because you were not up to the task of using it . . .
Look, I'm no EE, but do things the right way . . . if you start putting too
much current or voltage on the wrong pins. You'll end up frying the
processor. Then no doubt start telling the BBB is garbage because you were
not up to the task of using it . . .
Take a look at the schematics and just peek at the USB specs, it is within the
range asked about. The VBUS line on the USB host connector is designed to
handle 5V and the switch on there is at least 100mA.
Once again, look at the specs!