#avr Logs

Jan 25 2019

07:58 AM merethan_w: If a mcu is specced at 32Mhz. by Atmel, do they mean 32.000.000Hz. or ‭33.554.432‬Hz.?
08:02 AM LeoNerd: M is 10^6; so the base-10 version
08:02 AM merethan_w: So when speccing the oscillator they have 1000 as kilo & mega prefixes, not 1024?
08:02 AM merethan_w: correct?
08:18 AM polprog: if only they ran at MiHz then it would be so easy to get equal second intervals
08:18 AM polprog: but weve gotta use 32k768 xtals
08:32 AM davor_ is now known as davor
08:47 AM rue_bed: no
08:47 AM rue_bed: if you want, you can use 32k000 crystals
08:47 AM rue_bed: but getting 1/100 sec resolution isn't easily avilable
08:47 AM rue_bed: cause binary dividers
08:58 AM horohoro: hello everyone
08:59 AM horohoro: glad to be back here
09:03 AM polprog: definitely easier to get those right if you use a crystal that is of base 2 frequency.
09:22 AM nohit: hi horohoro
09:22 AM horohoro: hello nohit
10:12 AM [1]MrMobius is now known as MrMobius
01:10 PM jesseg: actually, to get a 100hz resolution, you might want a crystal that was like 3,276,800hz or some power of 2 of that
01:11 PM jesseg: so after dividing by a base 2 number, you'd still have 100hz left over
01:11 PM LeoNerd: Getting 100Hz is easy in CTC mode
01:12 PM jesseg: personally I usually end up using a crystal that's a base 2 multiple of 115200 lol
01:12 PM LeoNerd: 16MHz div16 gives you a 1MHz counter tick rate. Count to 9999 and that's 100Hz
01:12 PM LeoNerd: Or div64 and count to 2499
01:12 PM LeoNerd: A little bit harder to do on an 8bit counter, I'll admit
01:13 PM LeoNerd: div64 and count to 99 gives you 2.5kHz, then do your own counter logic in there to count to 25 = 100Hz
01:13 PM jesseg: yeah with 16 bit fractional divider with pll boost and pre/post scalers you have a lot of flexibility :P
01:14 PM jesseg: the rest you can do in software
01:15 PM jesseg: but with simple architecture getting symetrical jitter free 100hz with a 32768 hz crystal might be tricky :P
01:15 PM LeoNerd: That one is harder for sure :)
11:46 PM day_ is now known as day