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Topic: [SOLVED] Low-speed serial: How is it possible? (Read 2188 times) previous topic - next topic

igendel

What hardware are you using as the serial adapter? If is the soak on an uno, with the 16u2 it has an Atmel uart too with the same limitation, and probably a naive enough implementation of usb-serial on the chip that it could be doing the same thing
That makes sense. I only tried this with an Uno R3; If Windows simply trusts the adapter for correct timing, this explains the terminal softwares' behavior as well.
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jboyton

"He"? I'm right here man...  :)
Sorry about the third person reference, I didn't mean anything by it. I'm still learning how to behave properly on the internet.


1. The Arduino can't in fact go below 245 baud (as expected according to the datasheet). Sending lower values to Serial.begin just makes a mess and causes data to be sent at higher rates.
Not that you'd want to do it this way, but you could change the system clock prescaler rate in your sketch and achieve 110 baud.

igendel

Sorry about the third person reference, I didn't mean anything by it. I'm still learning how to behave properly on the internet.
Don't worry about it.

Not that you'd want to do it this way, but you could change the system clock prescaler rate in your sketch and achieve 110 baud.
It all began because I simply got curious, what's the lowest baud rate the Arduino could handle without tricks (the Serial documentation is silent on this). I have yet to find an actual use for such low rates.

I did wonder once, what would happen if I clocked an MCU using an LDR on the roof as an external clock source. Could it provide a day-scale clock? And if I wrote a loop that's exactly 7 instruction cycles long, can I make the setup light an LED every Sunday?  :D 
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jboyton

I think you could. According to the datasheet the minimum external clock frequency is zero.

DrAzzy

#19
Oct 02, 2015, 09:44 pm Last Edit: Oct 02, 2015, 09:45 pm by DrAzzy
Well, you'd need to write it in pure C, as digitalWrite() would take over a month to run, not to mention setup() and init()... and an LDR isn't a very clean clock source.... You'd need some external parts to get something close enough to a clock signal out of it I think...


Re: forum conventions

I've seen and used "he" (or she, if girls ever posted - they must all be great at electronics, I hardly ever see any asking for help here) to refer to another poster in a thread, even if said poster is still active. In fact, he's you're the first person I've seen take issue with that construction. It's most commonly used when commenting on a question raised by another poster in response to the "he"-person, where one is providing an answer to that other comment, but which is expected to be of little value to the "he"-person (maybe because others have already covered what he needs to know), hence I'm addressing the other posters rather than the "he"-person.
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igendel

Well, you'd need to write it in pure C, as digitalWrite() would take over a month to run, not to mention setup() and init()... and an LDR isn't a very clean clock source.... You'd need some external parts to get something close enough to a clock signal out of it I think...
I had no intention to use Arduino functions  :)  I do most of my work these days on Atmel Studio / MPLAB X and bare MCUs. The Arduinos I keep mostly for quick & dirty hacks. Recently I started writing a "Wiki" in my native language for beginners on Embedded and Arduino, hence my interest in the inner working of Arduino.

If the clock input pin is schmitt-triggered like the digital inputs, perhaps it's not impossible. But as you said, it'll require some setup and quite a few field measurements (clouds, full moon etc.)

Re: forum conventions
This is really a non-issue, I even added a smiley there in the first place...
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jboyton

I'm glad it's a non-issue for you but I could understand how it might bother someone.

jboyton

...or she, if girls ever posted...
Girls? I think you mean women.

My email address is obviously female. My username is ambiguous. But maybe my posting style gives it away? It's fun sometimes to try and figure out gender based on writing alone.

igendel

Girls? I think you mean women.

My email address is obviously female. My username is ambiguous. But maybe my posting style gives it away? It's fun sometimes to try and figure out gender based on writing alone.

So when I said "I'm right here, man"...? oh my, what a fine mess this has become!  :D
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DrAzzy

Girls? I think you mean women.

My email address is obviously female. My username is ambiguous. But maybe my posting style gives it away? It's fun sometimes to try and figure out gender based on writing alone.

Wouldn't have guessed, I was sure you were a guy. Somehow I thought your first name was John, but I don't know why - maybe there was someone else named john boynton (that name sounds extremely familiar), and that's what confused me

I usually use "guys" and "girls" to refer to males and females without specifying age range - there doesn't seem to be a generic term to include female adults and female children (since a good portion of the posts here are highschoolers asking for help on their homework), and I've heard "girls" used to refer to females of all ages more often than I've heard "women" used for that.
ATTinyCore and megaTinyCore for all ATtiny, DxCore for DA/DB-series! github.com/SpenceKonde
http://drazzy.com/package_drazzy.com_index.json
ATtiny breakouts, mosfets, awesome prototyping board in my store http://tindie.com/stores/DrAzzy

jboyton

Wouldn't have guessed, I was sure you were a guy.
I didn't say I wasn't. Just my email/username. You're not really a doctor are you?

I usually use "guys" and "girls" to refer to males and females without specifying age range - there doesn't seem to be a generic term to include female adults and female children...
Yeah, I know. It's no big deal to me. But many women aren't happy being referred to as girls.

DrAzzy

#26
Oct 02, 2015, 11:18 pm Last Edit: Oct 02, 2015, 11:19 pm by DrAzzy
Oh, I see - from the way you phrased that, I'd have assumed that's what you were saying... Man, this thread's making my head spin - you see, that's why he you shouldn't use such a low baud rate!
ATTinyCore and megaTinyCore for all ATtiny, DxCore for DA/DB-series! github.com/SpenceKonde
http://drazzy.com/package_drazzy.com_index.json
ATtiny breakouts, mosfets, awesome prototyping board in my store http://tindie.com/stores/DrAzzy

igendel

you see, that's why he you shouldn't use such a low baud rate!
Hehe, it'll never happen again, I promise!  :smiley-grin:
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