#avr Logs

Mar 01 2022

04:42 AM specing_ is now known as specing
10:55 AM mikee is now known as saxicola
11:57 AM WormFood: <LeoNerd> ...It generally works absolutely fine at 115.2kbaud, but... sometimes overnight when it gets cold it loses the odd byte or two <-- that problem is most likely due to your osc/xtal changing frequency due to the temp, to put it enough out of tolerance. Reducing the speed (and/or number of bits) will reduce the effect of serial clock skew. Switch to 5-bits (instead of 8), and it'd probably work at 115.2k
11:57 AM WormFood: all the time ;)
11:59 AM qu1j0t3: very quick and easy to check that
11:59 AM qu1j0t3: if you have freeze spray, anyhow
12:00 PM WormFood: right, and a frequency counter ;)
12:00 PM qu1j0t3: oops, my assumptions are showing ;-)
12:00 PM * qu1j0t3 hugs his 5335A
12:00 PM WormFood: well, not a requirement, it'd be handy to see what frequency the clock is really running at
12:00 PM qu1j0t3: i don't have freeze spray tho
12:00 PM qu1j0t3: but ice cube will do
12:00 PM qu1j0t3: suitably buffered
12:01 PM WormFood: too much water from melting, unless you're very careful
12:01 PM qu1j0t3: trivial to fix
12:01 PM WormFood: indeed
12:01 PM qu1j0t3: i _do_ have about 3000 ziplok bags here
12:01 PM qu1j0t3: most airtight :)
12:01 PM WormFood: I like airtight
12:02 PM WormFood: how'd you get that many bags? A ziplok truck got hit by a train near you?
12:02 PM qu1j0t3: slight exaggeration, but i keep the digikey overpacking ones, and the kitchen generates many more
12:02 PM qu1j0t3: anyway you only need one good one for this!
12:03 PM qu1j0t3: might try this some time, since i do have a freq counter, and some junk crystals i never tried to get running
12:03 PM * WormFood remembers once as a kid, a cheese truck was hit by a train, and when the insurance wrote it off as a total loss, whoever was there could take whatever cheese they could carry. We had soooo much cheese in the fridge then.
12:03 PM qu1j0t3: COOL
12:04 PM WormFood: but, testing a missing "odd byte or two", is kinda hard, unless the problem shows up right away.
12:05 PM qu1j0t3: yeah i was thinking about just meauring freq. you could probably infer a lot from that & i think your theory is good
12:05 PM WormFood: I mean, how do you know it's really cold enough
12:05 PM qu1j0t3: but i don't reclal off hand what an expected temp co is
12:05 PM qu1j0t3: maybe cheap xtals are horrible? idk
12:05 PM WormFood: I know it's enough to need to build a "crystal oven" to keep the temp steady
12:06 PM WormFood: I mean, for some applications.
12:07 PM WormFood: I'd expect crystals to be mostly the same. It's just a piece of quarts. They are cut from different parts of the crystal, and at different angles, for different uses, but I don't suspect there is a lot of variation. At least, not like caps. But I'm just guessing.
12:10 PM qu1j0t3: yeah, the 5335A itself has TCXO
12:11 PM WormFood: https://wormfood.net/avrbaudcalc.php <-- did anyone ever notice, that if you mouse-over the crystal speed on the baud rate tables, it will give you some info about that frequency? (that's not a new feature, it's been there over a decade)
12:38 PM cehteh: no :D
01:39 PM WormFood: I actually have info on about 150 different frequencies. The only problem is, you have to be dead on to make it work. So 3.68 is not good enough to get the info, you have to use 3.6864 Mhz, for example.
01:51 PM cehteh: :)
01:51 PM cehteh: add a 2nd 'special sauce' page .. would be to convoluted when you add any more to the main page
01:52 PM cehteh: or make some extensive fitlering where one can put checkmarks on features
02:33 PM saxicola is now known as plankton
03:12 PM LeoNerd: So.. fun story: I think I've left the A0 pin of an I²C sensor floating (bad me). It turns out to be almost-super reliablely low though, and the chip almost-always talks as 0x4A. Except when the weather gets cold, and it flips to 0x4B instead
03:14 PM qu1j0t3: ha
03:15 PM cehteh: 'almost' .. haha
03:18 PM cehteh: maybe you patent it and sell it as 'cold-weather sensor' :)
03:18 PM LeoNerd: The chip is an ambient light sensor, next to the atmospheric sensor already in the box. It can do temperature a lot better :P
03:20 PM cehteh: then brand it as fallback :)
04:06 PM saxicola: LeoNerd: :)
04:11 PM qu1j0t3: it cannot be a worse sensor than a DHT22
04:23 PM LeoNerd: Oh it's much nicer.. it actually talks I²C
04:25 PM qu1j0t3: :)
04:25 PM qu1j0t3: i can't get my dht22's to talk much at all
04:25 PM qu1j0t3: they've got about 0 9's uptime
04:25 PM qu1j0t3: "When I feel like it, ok?"
05:05 PM mindw0rk_ is now known as mindw0rk