555 countdown timer design question

[Dannyx]

Re: 555 countdown timer design question

Always faster to find a solution already made instead of building one yourself!

Was that sarcasm ? Yes, it is easier, but for beginners it's easier to adapt an existing code than trying to create one from scratch - found that myself in the past days. I'm now slowly getting the hang of it and starting to understand how it operates.

[eccerr0r]

Re: 555 countdown timer design question

No, that's the way things go... me, see, I still haven't gotten mine out before you found a solution code
(but that discrete solution...)

[stj]

Re: 555 countdown timer design question

i'm actually surprised that the arduino-suit does not include a simulator yet.

[eccerr0r]

Re: 555 countdown timer design question

I have yet to use an emulator, never seen one for Linux yet
Fortunately most of the times my programs work well enough to see some life, and adding that CLI is helpful in debug

[stj]

Re: 555 countdown timer design question

there is a Linux avr simulator.
https://github.com/buserror/simavr

[eccerr0r]

Re: 555 countdown timer design question

Looks like this was after when I started with AVRs... no 90S2313 and 90S4433 support... they do support the similar Tiny2313 and Mega8 but they're not quite the same.

[stj]

Re: 555 countdown timer design question

so fix it, you have the source there.

[eccerr0r]

Re: 555 countdown timer design question

But...but... I've been working with this over a decade and never needed it!

[stj]

Re: 555 countdown timer design question

so dont.

[Dannyx]

Re: 555 countdown timer design question

Quick look at how the power supply for this thing is gonna look I suppose: interestingly, I was expecting the remote module to have a capacitor dropper like most cheap and cheerful China products tend to have, but it's actually got a tasty little switch mode power supply, operating in what appears to be a buck configuration, though there's no isolation as far as I can tell (notice the GND trace is common between the primary cap and the green secondary cap).

There's an unmarked switching regulator, a coil, a diode, two feedback resistors and that takes care of the 12v section. It's a cascading supply, meaning there's an additional 5v supply derived from the 12v one via a small 7805 regulator. It's this 5v supply I'm interested in: trying to keep the project as small as possible (so I could preferably tuck inside the light itself, though it's not a requirement), I'm not too sure whether it's better/safer to stick with this PSU to also power my arduino or to use an off-the shelf power brick....I could lower the part count even further by dropping the primary voltage straight to 5v by messing with those feedback resistors so I can eliminate the 7805 entirely....I'd probably add a varistor because I'm not liking the idea of letting my arduino "ride the live wire" like that with no protection whatsoever.....

[budm]

Re: 555 countdown timer design question

Since it is not isolated power supply I would be really careful when hooking up PC or what ever you will need. I would go with isolated power supply for safety concern.

[Dannyx]

Re: 555 countdown timer design question

Since it is not isolated power supply I would be really careful when hooking up PC or what ever you will need. I would go with isolated power supply for safety concern.

True that. Power pack/wall wart, whatever you call it, seems to be the way to go.

[Dannyx]

Re: 555 countdown timer design question

My Mini just arrived today and it works, but I'm not sure about its operating voltage: while I specifically asked for a 5v model when I bought it, I'm not entirely sure I really got the 5v model in the end. I applied 5v to the RAW pin and it came on just fine, but I only get 3.3v on the VCC pin....the regulator says L05 so the data is contradicting. I guess one sure way to find out is to define a pin as high and measure the output....

[stj]

Re: 555 countdown timer design question

what does it say on the crystal?
3.3v models only run at 8MHz, while 5v ones run at 16MHz

[Dannyx]

Re: 555 countdown timer design question

what does it say on the crystal?
3.3v models only run at 8MHz, while 5v ones run at 16MHz

Says 16000 on the crystal, so I believe it should be a 5 volter.....just made up a new word apparently

[Dannyx]

Re: 555 countdown timer design question

Finally back on this project and I'm having some issues: can't get my CH341 programmer to work with the damn thing and the information you get online is disappointing if anything: not nearly thorough enough to get a beginner up and running, as it's missing some important details, which may seem self explanatory to some, but others, myself included have some questions.
I'm using a CH341 interface which I normally use for programming TV SPIs. I HAVE used it as a serial COM port before, when I connected it to a TP Link router to try and unbrick it, so I KNOW the adapter works for that purpose. I think I'm doing something wrong on the Arduino's side: I connected TX to RX and vice versa between the two boards, as well as GND of course, but I get an error saying |Not in sync" after 10 upload attempts. I'm not sure I got my arduino software configured properly...aside from obviously selecting "arduino mini" and the correct COM port corresponding to the serial programmer, I can't see too many other options like I did when I messed around with that router where I had to also set the baud rate and flow control.

Another slight mystery is that reset pin of the mini...what should I do with it ? Let it float or use a 0.1uF cap between it and GND ? Does the board need to be put into some sort of "programming mode" or it just works at any point, even if the sketch already on the arduino is running ? Again, the info is not thorough enough on this....

This SHOULD still work right ?! I don't see much difference between my adapter and others demonstrated online...a little help pls ?

[stj]

Re: 555 countdown timer design question

let the reset float - it should have a pullup on the board, connect tx,rx & ground and make sure the arduino software is set to use the right comport.
try swapping tx and rx if it's not getting anywhere

[Dannyx]

Re: 555 countdown timer design question

I did manage to get it to upload one sketch, by some sort of luck....and I say that because I thought I got it going and the problem got solved (I selected ProMini in the menu), but then when I tried uploading another one, I got "programmer not responding" again, even though I touched no-bloody-thing....the wires going from the arduino to the CH341 thing are about 20cm long...could that be too much and cause spotty functionality ?

[Dannyx]

Re: 555 countdown timer design question

Same thing happened just now: it decided to upload once again...I still don't know what gets it going...I even tried replacing the wires with a shorter piece (shielded even) but made no difference.

My mate suggested the CH341 adapter is crap.....

Guess I'll also try with the MISO MOSI CSK pins.....I believe it's called ISP ?

[stj]

Re: 555 countdown timer design question

isp needs a dedicated programmer - preferably a USBasp

i can tell you why your second upload failed,
on a full arduino the reset pin on the atmel is linked to a handshake line on the serial port/chip so the software can reset the atmel into it's bootloader.
can you dig out a 100n film cap?