9.6Mhz is right on the ragged edge with a protection diode in place. Atmel’s datasheet shows that up to 10Mhz is OK for 2.7-5.5v, but the diode drops around 0.2v or more. So at 2.9v the ATtiny13A sees 2.7v. There may be other considerations that push you over the edge in certain circumstances.
In other words if it’s possible I’d try and stick to 4.8Mhz rather than 9.6Mhz, just to have all your bases covered all the time.
What offtime values are you using and how much time is it taking to save?
I’m saying that it may malfunction once voltage drops low enough. There will be no damage to the driver, but it’s anybody’s guess what could happen. LVP could fail, that would be my primary concern.
How many seconds does the driver take to save the last used mode?
If I understand correctly, that will change the PWM speed to about 1.2 kHz or 2.4 kHz… which is much easier to see. Even 4.5 kHz bugs me; I can’t not see it strobing unless it’s at least 10 kHz or so.
But if it looks fine to you, then it sounds like you’ve found a solution.
I got the 1.2 / 2.4 kHz thing from the header comment in a STAR firmware file. I don’t know if it’s correct.
In any case, the shower is actually pretty bad at showing PWM. The reason is because water droplets change shape as they fall, and small droplets change shape very quickly. So, the droplets will appear to flicker even under a constant-output light.
To test PWM I recommend quickly waving a white notecard (or other thin white stiff sheet) through the beam instead. Here are a couple images showing 488 Hz PWM versus 4.5 kHz PWM:
These images fairly accurately show how the lights actually look to my eyes under regular use… but I’m unusually sensitive to the flickering.
Good images ToyKeeper. I missed your last post and was pretty confused about bdiddle’s post after that saying that someone was right. Hence my rather pedestrian response.
bdiddle… the current firmware can be confusing to setup. Please post (not here - use somewhere else like pastebin or whatever you want) examples of you the entire program you used with Phase Correct and then with Fast PWM. It’s reasonably possible that you were not actually making the changes correctly.
TK, if you don’t mind will you please share the camera settings you used to determine those PWM’s?
So many variables with shutter speed, wondering how you got there. (I can freeze a high speed object, or make a snail look fast, depends on what I’m trying to achieve) Point being, how do you do the math after determining shutter speed.
I have found that with all the road construction in my area there is always dust in the air, this dust will show PWM quite well. I would imagine snow flakes would too. (not like I have those to shoot, it was around 70º today)
I wonder what settings it would take to show the faster PWM? Might be fun trying, I’d like to see what some of mine are actually doing but need some info.
Thanks
Edit: Isn’t it also pertinent to establish speed of the card in fps to get an accurate frame count?
I measure PWM speed with a very small microphone and a guitar tuner app called PitchLab. When the pulsing is audible, the sound is by far the easiest way to get the frequency.
For some reason, most lights will get louder when they’re aimed point-blank at fabric. I don’t know why that happens, but it’s pretty helpful for measurement.
The pictures are just to give a rough idea what the resulting beam looks like, and how to visually check for PWM. I can only get a ballpark idea what the speed is through visual means. This is at least enough to sanity-check my sound-based measurements though.
I haven’t found airborne particles to be very useful for PWM. For example, this ice fog was shot with a 4.5 kHz PWM light. The particles were small enough to hang in the air instead of falling, and they showed no sign of flickering in the camera as the wind blew them around.
Annother thing about the large copper area is that it reduces unwanted high frequency effects. It stabilizes ground at high frequencies with the capacitance between the layers.