In wall light switch node - Custom PCB

m26872

You'll need low MHz for ot to work when battery runs out and voltage decreases.
Those fuses are for 1MHz, not for 8MHz.
I've never used MYSBootloader. Someone else has to confirm the settings if you use this.

Samuel235

Lower clock speed would last through the low power phase of the battery. Obviously, thank you for pointing that out! However, I'm looking at Maniacs battery testing graph and the battery is stable down to around 2.4v for around 150 hours, then it will rapidly drop off to 0v, so I'm thinking "is the lower clock speed really worth the extra 10 hours of use?".

The fuses, although I am going off of what you suggested, i entered them into my fuse calculator and its showing up at 8MHz, with no modification needed to the speed.... I'm a little confused at this part as you have now said that those fuses are for 1MHz.

I'm now wondering if its worth using MYSBootloader or the one you used, I can see that you used this and programmed through the Arduino IDE, from your post you said you're more comfortable with using the Arduino IDE (Which i am too, but can adapt if needed).

scalz

@samuel235: don't worry about 1mhz...there is no big difference 1Mhz vs 8Mhz at 3V in deepsleep mode. In deepsleep mode, at 3V 8Mhz internal rc, you can get 140nA. So you can't have such interesting diff.
In other hand, if node is wake up, you are in mA range, and here it can be interesting to play between clock and voltage ;) you can do it on the fly in sketch and it's good to know that for timing things, atmel clock and voltage are linked.
So i would suggest you to stay with internal rc 8Mhz, BOD 1.8V and MYSBootloader. If I remember right it should be ok. Other thing good to know, you can disable BOD=0V when in deepsleepmode (this is done like this in lib I think), but it's not a good practice to disable it when wake up. Keep 1.8V limit, it can prevent some bugs..All is described in datasheet ;)

Another thing good to know, as I see lot of peope estimation for coincell...there are lot of chance that you can't get the full coincell capacity, depending on the application, the use. A common "prevision is to plan 80% of its capacity. It's due to the rate of discharge of battery and coincell's one is small..
There are lot of others resources on the subjects but here few links :
https://www.dmcinfo.com/Portals/0/Blog Files/High pulse drain impact on CR2032 coin cell battery capacity.pdf
http://www.embedded.com/electronics-blogs/break-points/4429960/How-much-energy-can-you-really-get-from-a-coin-cell-
http://www.ti.com/lit/wp/swra349/swra349.pdf

Samuel235

@scalz This is the information that was much needed. Right, so my settings are going to be:

######## settings for 8Mhz internal clock

proMYSBL8.name=ATmega328 internal 8Mhz with MYSBootloader
proMYSBL8.upload.tool=avrdude
proMYSBL8.upload.protocol=arduino
proMYSBL8.upload.maximum_size=30720
proMYSBL8.upload.maximum_data_size=2048
proMYSBL8.upload.speed=57600
proMYSBL8.bootloader.tool=avrdude
proMYSBL8.bootloader.low_fuses=0x62
proMYSBL8.bootloader.high_fuses=0xD9
proMYSBL8.bootloader.extended_fuses=0xFE
proMYSBL8.bootloader.unlock_bits=0x3F
proMYSBL8.bootloader.lock_bits=0x3F
proMYSBL8.bootloader.file=MySensors/MYSBootloader.hex
proMYSBL8.build.mcu=atmega328p
proMYSBL8.build.f_cpu=8000000L
proMYSBL8.build.board=AVR_UNO
proMYSBL8.build.core=arduino
proMYSBL8.build.variant=standard

At the moment the fuses are set using Hexadecimal notation, I'm sure that I read somewhere that to burn this using a Arduino IDE you need to use normal binary rather than Hex. Do you know if Hex is okay for Arduino IDE?

I've got those fuses set to enable 1.8v BoD, 8MHz clock with a 65ms delay on startup. This will use MYSBootloader too. Does this sound okay to now edit my boards.txt, and burn the MYSBootloader.hex file to the chip? I'm using a USBASP device connected to my ISP connection. Am i forgetting anything at all here? As far as I'm aware of, i now plug the board and USBASP into my computer, load the .hex file into arduino IDE and burn using the board config i have put into my boards.txt file. Then i can use my FTDI adapter to then burn sketches to the board through the arduino IDE?

I know that to some people I may be asking what seems like the same questions over and over but I'm starting to feel very confident with embedded chips now. Thank you!

scalz

no problem :) yes, it sounds ok...that's how I do too. But I don't use mysbootloader, i use dualoptiboot (sensebender bootloader). for the hex/bin fuse notation, I use hexa.

m26872

@samuel235

You could be rigth regarding the battery. I've no coin cell experience.
You noticed the check mark by the 'divide clock by 8' ?
If you by 'program' normal ftdi flash, then yes. I didn't program bootloader with Arduino.

Samuel235

@scalz

Is there a reason to use dualoptiboot over MYSBootloader or is that just something you did for no reason?

Did you use Arduino IDE to burn your bootloader, if so then i can confirm its okay to use Hexa for my board with arduino IDE, if you didn't i will have to convert it to normal binary.

@m26872

I have just realised that you burn your bootloader with the check mark of 8MHz but then the board.txt is configured to set it to 1MHz, is that what you're trying to tell me? I'm not too sure on your last point, i don't get what you're trying to say if i'm honest, could you elaborate a little? Sorry.

scalz

@samuel235: yes, always good reasons ;) I have tried both. both works well. I like the "buffer style" of dualoptiboot. plus no mysensors lib in bootloader, few others reasons...but mysbootloader is very cool too and simple. So don't worry about this :) it's a matter of taste, each have their pros&cons.
Yes, use arduino ide to burn bootloader + hexa is ok.

Samuel235

@scalz - Perfect. I will see how i get on with the MYSBootloader style. Soon as i get back i will burn these settings to my uC and see how i get on. I will come back with the results when i'm done. :)

m26872

@scalz

Don't know if good practice or not, but I run 328p + nRF down to 1.6V very stable. Could depend on a lot things and conditions of course. You said "some bugs" - do you know more what risks there are? Permanent damages etc?
Do you know if the 'Divide clock by 8" (8MHz or 1MHz) also can be changed on-fly-with code? If so, does it matter which speed set by fuse and thus used at start-up?
Great thanks for the coin cell info!

m26872

@samuel235 I meant that you should untick this to use 8MHz. Provided that you don't change it on-the-fly somehow.

m26872

@samuel235 Sorry for not elaborating. I've been mobile all day until now. And my phone also seems to have a few issues with the forum.

Samuel235

@m26872 Ahh right okay, good job i caught your reply before burning it haha! So if i set it to 8MHz internal with 64ms delay and untick that divide by 8 option, that'll be good?

m26872

Yes. but don't forget to enable the boot reset vector.

m26872

@samuel235 I have not checked if the bootloader size and baud rate matches fuse settings.

scalz

@m26872:

for bod=0v, problems could be flash corruption for instance..so it's good to know (it's explained in datasheet that for instance it ensures that a flash write is completely done before reset, I think it makes sense, plus I imagine that there are some internal things with voltage levels related stuff. but I'm not a guru on this....). So my interpretation is sometimes we don't care about it for sleepmode, for instance, and sometimes in wakeup, it's important or not, depending of tasks involved...
maybe I should have said a good practice is to know what you do, lol!
for prescaler, are you asking for something like this : http://www.gammon.com.au/forum/?id=11497&reply=7#reply7
glad to share what I learn :)

m26872

@scalz .

maybe I should have said a good practice is to know what you do, lol!

l don't fulfil that either, lol! :smiley:

Thanks for the prescaler info. Seems like a yes - it can be changed on-the-fly, but for me it's a No. I won't even dare to think of consequences for the rest of the software.

Samuel235

@m26872 said:

@samuel235 I have not checked if the bootloader size and baud rate matches fuse settings.

I'm not 100% sure of what you mean here, on the fuse calculator there is not an option to specify the baud rate.... As for the bootloader size, the calculator is set to "Boot Flash section size=2048 words Boot start address=$3800; [BOOTSZ=00]". As this is the highest it can be I'm assuming it is correct, however i will try and check the size of the MYSBootloader.hex size and see if it is below 2048 words (Is this what this setting means?).

m26872

@samuel235 No, but bootloader and boards.txt must have same buad rate. I think you already have the correct though since 8MHz is pretty much standard clock speed. Slower clock would require lower buad rate.

Samuel235

@m26872 Is there a way to read the .hex file to see the specified baud rate before i go and brick the chip? Also, just to confirm, i have to burn the fuse settings in AVRDUDE then burn the bootloader with arduino IDE. Is there anything I'm failing to understand, i only have one more uC here at the moment and i don't want to brick several of them :(

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