#avr Logs

Dec 31 2019

03:06 AM Thrashbarg_ is now known as Thrashbarg
09:09 AM twnqx: Fuchikoma: that's probably it; however i don't see why the chipi gets so hot from it. with P=U*I, U=I*R => P=R*I², and R=0.8Ohm (worst case, one bridge), I = 0.65A => P=0.338W it shouldn't try to free itself from the PCB...
09:12 AM twnqx: my old driver didn't heat up at all, and that had a similar on resistance (lower high-side, higher low-side)
09:12 AM twnqx: but maybe it was using lower holding torque...
10:54 AM Fuchikoma: In my experience with the 3D printer community, we push the stepper drivers pretty hard and they often got hot. I don't think it's unusual.
10:55 AM Fuchikoma: The power dissipation (e.g. 0.34W) doesn't really speak to temperature, plus you might not be estimating the power dissipation of the device properly
10:56 AM Fuchikoma: What driver is it?
11:01 AM twnqx: L6474PD
11:05 AM twnqx: but i think on the demo board i am using (kind of an arduino hat) the layout isn't the greatest for thermal dissipation...
11:54 AM rue_bed: Fuchikoma, dial down the current
11:55 AM rue_bed: never use steppers for battery powered things
12:13 PM Fuchikoma: rue_bed: It was mostly because we're all too cheap to buy high quality drivers of the proper size, and ran them way overvoltage for better performance.
12:15 PM Fuchikoma: When you run a 3 volt stepper motor at 12 volts or more, you really put a lot of faith in the driver's current limiting to keep the magic smoke contained :D
01:15 PM rue_mohr: happy new year to those of you in the future!
02:45 PM atk: With chips such as the ATmega2560 and the bootloader functionality, does the firmware need to be recompiled with a different ldscript for it to still work on the chip?
02:45 PM atk: do offsets change etc?
02:47 PM rue_mohr: well you compile for the chip you have
02:51 PM atk: right but if I have a chip and I flash a bootloader onto it which can then let you flash over serial, the code gets presumably put at an offset
02:51 PM atk: or does AVR somehow fix this with some magic MMU thing?
02:52 PM atk: I can read the docs and work it out myself I was just hoping for a quick answer
02:52 PM atk: because my prior experience with an ARM chip with no MMU was that if you put a bootloader on there your code needs to have a new LD script which matches where that bootloader placed your code
02:53 PM atk: rather than everything starting at offset x it was at offset x + y
02:53 PM PoppaVic: be advised: code is not "script". and MMU with general AVR is laughable.
02:55 PM PoppaVic: bootloaders are waaaaaaaayyyy oldschool. The binary itself could be considered "script". The results are still binary.
02:55 PM atk: I am aware that having an MMU on an AVR is a big ask but I recall there being something in the docs the long time ago that I looked into it that AVRs had some special bootloader mode where you could keep your offsets on your binary intact and things would work
02:55 PM PoppaVic: no
02:55 PM PoppaVic: The bootloader is a binary-speaking loader/debug
02:56 PM atk: and when I look into reusing those arduino-style boards which come with a bootloader and allow flashing over serial everyone seems to insist that nothing special needs to be done on the compilation side to get code to work on those boards
02:56 PM PoppaVic: the bootloader runs in a special block of memory and speaks to a special block of memory. the CODE it may store is ... moot
02:56 PM atk: you can compile a blinky LED and flash it with an ISP and it works
02:56 PM atk: and then flash a bootloader and flash it over the bootloader without any recompilation and it works
02:56 PM PoppaVic: yep. Welcome to the joys of mcu's
02:57 PM atk: so that will work and I'm not seeing things?
02:57 PM PoppaVic: yes
02:57 PM atk: right, which is confusing to me coming from an ARM board where if you have a bootloader it's just a normal firmware which runs normally and if you flash using the bootloader your code ends up logically in memory after the bootloader
02:57 PM PoppaVic: the bootloader will write to flash; the flash may include bootloader; but code only runs from flash and bootloading only runs in bootloader segment.
02:58 PM atk: right
02:58 PM atk: so it's a special memory segment
02:58 PM atk: okay, that explains it
02:58 PM PoppaVic: I am so happy I packed my arms and all mcu shit away. So tire of the shit
02:58 PM atk: thanks
02:58 PM PoppaVic: tired
02:58 PM atk: ARM is fine :P why do you dislike it?
03:00 PM PoppaVic: I don't dislike it - yet. I noted the new ones obviate the older books and they have shit support-code/examples.. "frameworks" are hooey.. I got a decent price, but lost the interest and went back to reloading for the zombie-apocalypse.
03:00 PM atk: I see
03:00 PM atk: But this is #avr not #reloading
03:00 PM atk: :P
03:00 PM PoppaVic: I actually looked forward to the arms, but.. screw it.. I'd rather punch paper.
11:06 PM rue_mohr: HAPPY NEW YEAR!!!!!
11:51 PM day__ is now known as day