#avr Logs

Jun 29 2022

12:28 AM Tigzee: nope. maybe its just the 3rd crystal works better
04:15 AM exp: Tigzee: from reading up it seems your problem is your AVR won't overclock to 24Mhz?
04:15 AM exp: leads hanging off pins can easily provide the ~10pF needed to start a crystal up so that's fine
04:15 AM exp: i see a lot of logic analyser outputs, but perhaps you could succinctly describe the problem for newcomers
09:50 AM Tigzee: At first I couldn't get the attiny44a t to run at 24mhz (kept coming back at 8mhz). I ended up making 3 unique setups (different capcitors and different brand crystals). The last setup with no capacitor endedup working. I removed the capacitors from the first 2 setups and they still ran at 8mhz. So at this point I'm blaming an incompatibility between the crystals and atmel. (From what I have read, an option on old atmels "full swing"
09:50 AM Tigzee: would probably have fixed my problem)
09:51 AM Tigzee: I guess the big problem now is; if I needed to do this again, how would I know which crystals to buy?
09:59 AM cehteh: modern ones :D
10:00 AM cehteh: but i didnt know the tiny44 has fallback to internal osc when external doesnt work
10:00 AM LeoNerd: All the modern Tinies do that
10:00 AM cehteh: for the chips that have that there is some register which you can check iirc
10:00 AM LeoNerd: Also, why is anyone making new designs on the not-new tiny chips?
10:00 AM cehteh: i just didnt know
10:01 AM cehteh: weird thing was that it didnt run at all with crystal disconnected then
10:01 AM LeoNerd: The new chips are pretty robust in a lot of ways yes
10:01 AM cehteh: but mkay .. by reading datasheet and probing what i told you you could have figured that out
10:02 AM cehteh: well if timing is off it can be more desastrous than not running at all
10:02 AM cehteh: but i expect there are ways to handle that, but needs RTFM
10:03 AM cehteh: maybe there is even a ISR for clock fallback? dunno
10:26 AM LeoNerd: I believe there is yes
10:39 AM Tigzee: re: old tinys. Im a hobbyist and have a lot left over as I bought in bulk in 2013? but yes, I would buy a newer one vs on old one at this point
10:40 AM twnqx: i need a 1.8V serial port :(
10:41 AM Tigzee: cehteh, I didn't see anything about a clock fallback in the datasheet, and it doesn't work with no crystal. so Im thinking it's picking up a harmonic of the 24mhz (people use the term fundemental I think for it)
10:41 AM Tigzee: twnqx: resistors?
10:42 AM twnqx: i don't think i want to debug a SAS controller in an expensive server like that :P
10:43 AM Tigzee: do opto/electric-couplers work that low?
10:43 AM twnqx: i also don't know the pinout
10:44 AM twnqx: i maen.. i think i just want to read what it logs
10:45 AM Tigzee: If you have an atmel running at 3v3, I think it picks up 1.8v as high. You would have to check the datasheet
10:45 AM twnqx: this thing is driving me mad. it works perfectly if i boot in legacy (bios) mode, but the firmware crashes if the PC is booted in EFI mode
10:48 AM Tigzee: This is off topic. but you can't just switch between bios mode and EFI mode with an OS drive
10:49 AM twnqx: it is not :P
10:50 AM twnqx: (the os drive)
10:52 AM Tigzee: Then, ignoring the setup of how your switching between BIOS and EFI on the same machine AND your not booting off the controller, thats weird
10:52 AM Tigzee: BUT
10:53 AM Tigzee: I assume since your talking serial AND 1.8v, you have some idea what pins you are to use for debugging
10:53 AM LeoNerd: 74AVCH1T45. It's built for level-shifting, especially down to 1.8V
10:53 AM LeoNerd: *AVHC
10:53 AM LeoNerd: It has two VCC pins
10:54 AM twnqx: for now i'll just want to read
10:56 AM twnqx: so if 1.8V is good for "high" i'll be able to
10:57 AM Tigzee: LeoNerd, my search is coming back with 74AVC1T45
10:57 AM Tigzee: twnqx: if your only reading from the sas, you only need to have an input
10:58 AM LeoNerd: Ah; AVC. Yeah I forget quite what family
10:58 AM LeoNerd: But the 1T45 is the key part :)
11:01 AM Tigzee: twnqx: If it was me, and I was using used parts I have lying around. I would use a coupler, transistor or atmel to do the job for reading (probably in that order)
11:01 AM Tigzee: *to a logic level serial
11:04 AM Tigzee: twnqx: They make usb to 1.8v serial adapters. maybe get one of them with good reviews?
11:04 AM Tigzee: AND only hook up ground and rx pin on the adapter to figure out which pin is which?
02:47 PM twnqx: reading worked :) this sas controller apaprently has an operation mode the driver devs have never seen, and i can trigger it D:
03:08 PM qu1j0t3: uh oh twnqx