Which 10k IC-pot would you choose? It does not need to be fast, just simple to control. I wont use SPI, just some 2-4 wire easily programmed control for 555. Preferably daisy chainable.
I think you're going to have to give some more details. What do you mean by this:
stajo:
just some 2-4 wire easily programmed control for 555.
Where does the 555 come in to it?
Do you want a logarithmic or linear pot?
Can you do SMD or do you need something in a through hole package?
Oh yes thanks. Through hole is preferable for prototyping, I can live with SMD if it is not super small. Linear.
555, the timer: http://www.ti.com/lit/ds/symlink/na555.pdf
PS. I prefer not to use someones old unmaintained library. I like to do the programming myself.
I think most of us know what a 555 timer is. I have been using them for over 40 years. What we want to know is how the pot is related to using a 555 with an Arduino ptoject.
You can get a SPI pot and still write the code yourself. See bit banged SPI and/or the pulseOut() function.
To adjust the duty cycle. Cant provide schematic now sorry, on cell phone. Will do later.
groundFungus:
and/or the pulseOut() function.
Do you mean the shiftOut function?
Here is a general schematic, just screendumped from the internet. Dont care about the values. Im gonna hold approx 25 kHz and adjust the duty cycle of a couple of 555s. Its tested and working fine with a physical pot.
Do you mean the shiftOut function?
Yes, my brain made a rude noise.
Here is a general schematic, just screendumped from the internet. Dont care about the values. Im gonna hold approx 25 kHz and adjust the duty cycle of a couple of 555s. Its tested and working fine with a physical pot.
You will need an Arduino (or something like it) to control the pots. So why not use the PWM output of the Arduino? You can change the PWM frequency of the PWM outputs as well as the duty cycle.
6 or more independent of them. To much for even a mega and I prefer not to mess with clock cycle since I also use millis(). Plus Im nerding...
Back to the subject, any favvos?
Note that you can't control a 555 running on 9volt with a digital pot controlled by 5volt logic.
Well, most of them.
Leo..
You do not need all the horsepower of the 555
for that function. You can use two inverters.
Herb
stajo:
6 or more independent of them. To much for even a mega and I prefer not to mess with clock cycle since I also use millis(). Plus Im nerding...;
With a Mega you have 10 PWM capable pins.
Only one timer / counter controls the millis.
Why not use a PWM generator chip? Adafruit 16-Channel 12-bit PWM/Servo Driver - I2C interface (PCA9685) | The Pi Hut
I wont use SPI, just some 2-4 wire easily programmed control for 555. Preferably daisy chainable
Most digital pots are SPI, especially the DIL type. You can get I2C pots but they are mostly surface mount.
Typical of a pot is this https://uk.farnell.com/microchip/mcp4131-103e-p/potentiometer-digital-10k-8pdip/dp/1834951
Grumpy_Mike:
Why not use a PWM generator chip?
OP mentioned 25kHz (4-pin CPU fans?).
The PCA9685 can only do about 1kHz.
Leo..
Yes. And it also says ”Adjustable frequency PWM up to about 1.6 KHz” I dont want to adjust ferquency, but duty cycle.
This should take you to a decent list of digipots that can handle voltages higher than 5V.
stajo:
Yes. And it also says ”Adjustable frequency PWM up to about 1.6 KHz” I dont want to adjust ferquency, but duty cycle.
This PCA9685 is adjustable duty cycle.
You normally set the frequency for all 16 channels of this chip once, in setup().
Then you can load new (12-bit) PWM values into the chip as needed.
Can't do 25kHz though.
Leo..
stajo:
Yes. And it also says ”Adjustable frequency PWM up to about 1.6 KHz” I dont want to adjust ferquency, but duty cycle.
Yes but the adjustment of the duty cycle over a 12 bit resolution is possible at any frequency you use with this chip.
Does it have to be 25KHz? That seems very fast.
Grumpy_Mike:
Does it have to be 25KHz?
I think I got a 'yes' in post#15 to the question if this was for 4-pin CPU fans.
Leo..