I've scoured for a clear explanation of how to change the brown-out detection from the set 2.7v to the higher 4.3v but after much head banging, I'm turning to asking the question.
The root issue is I'm seeing instability of saved info to eeprom and much research leads me to believe it's due to a period of low voltage, and that setting the BOD to 4.3v will help. This is an automotive application with much filtering and regulating before the Arduino.
My issue is; I can successfully burn a new bootloader with BOD of 4.3v, but then my program either does not load (I get a clock sync error), or it doesn't fully work (some like interrupts sections don't work).
Does there exist a step by step that explains how to get from A to B without leaving out steps like "now change the extended fuse value in the boards.txt file" (just an example, don't know if this is actually needed)?
Board is Arduino Pro or Pro Mini (5V, 16 MHz) w/ ATmega328p. Can someone verify the fuse settings should be low_fuses=0xFF, high_fuses=0xDA, extended_fuses=0xFC to just set the BOD to 4.3v?
Thanks CrossRoads, that confirms 0xFC for setting BOD to 4.3v.
Now, how to do this without upsetting other bits??
I have an Uno that I can use the programmer, but I'm missing the "how to" do this with the Arduino IDE. What seems straight forward in the explanations I've read must be obvious to the experienced, but to me (the inexperienced) I can't get it to work. By that I mean I'm not clear on the steps to take. I keep running in to statements like "now you can program your board...". Great, and I can fly a plane too, but after taking lessons and tests!
As far as I know, you can only set the Fuses with a Programmer connected to the ICSP pins.
Change the fuses in boards.txt, then Burn Bootloader to change them.
The other two bytes will just get reprogrammed with the same bytes again if you didn't change them.
There may be a way with avrdude commands, I've never tried that.
Easiest way is with a USBAsp - with that, you just connect up the isp lines (see countless instructions ) to the usbasp, and can set fuse bits with the "extreme burner avr" tool, which has a nice graphical interface.
Saves you having to figure out the avrdude syntax and the usbasp is more reliable in general.
Minicore, hansibull 'score for the 328/328p and it's smaller kin may also provide menu option for bod level when burning bootloader (its technically easy to implement the menu option in a third party hardware package)
@hansibul, thank you! I think that gets me close, but I don't have a bare 328P - I have a ProMini. Assuming I can skip all the caps and such and connect my Uno as a programmer to the mini via the MISO, MOSI, Reset, +5, and GND pins?
And as a sequence, do you:
Program the bootloader (Uno)
Connect the bootloader to the mini via the pinout supplied
Burn the bootloader to the mini
Disconnect everything and load my code to the mini
I understand, but can skip all the caps and such and connect my Uno as a programmer to the mini via the MISO, MOSI, Reset, +5, and GND pins? Or do I need to add the caps and such?
Yep, that's correct. When you hit "burn booloader", you actually set the fuse bits first, then uploading the bootloader, changing the clock frequency and BOD setting without reburning the fuses/bootloader won't have any effect
Thought I had it... after following the above (changed the BOD setting in the boards.txt for my board) and received this error:
avrdude: Error: Could not find USBtiny device (0x2341/0x49)
Error while burning bootloader.
Strange because I'm not using or targeting a USBtiny device....
I'm still getting errors: the latest, after selecting the programmer "Arduino as ISP", is this
Arduino: 1.6.5 (Windows 8.1), Board: "Arduino Pro or Pro Mini, ATmega328 (5V, 16 MHz)"
avrdude: Yikes! Invalid device signature.
Double check connections and try again, or use -F to override
You can use avrdude to read out the fuses. I'll strongly recommend Engbedded's AVR fuse calc rather than struggling with the datasheets, like CrossRoads wants you to do. Simply select your microcontroller, and insert your fuses at the bottom. The corresponding settings will appear If you have a look at the output from avrdude (after you've burnt the bootloader), it's actually telling you the new fuse settings (high, low and extended fuses).
WestfW has a nice sketch called fusebytes that reads the fuses and displays lots of info via the Serial Monitor.
That will verify it for you.
You can also go into IDE preferences and check show verbose output during upload. Then when you burn the bootloader you will see the avrdude command lines used to burn the bootloader and set the fuses. Just look at what extended fuse byte is being written.
When you upload code using a programmer, such as with Shift-Upload, it overwrites the bootloader. So you will always have to upload your code using a programmer until the next time you burn the bootloader. If you have a bootloader installed, you can do a regular serial upload such as with an FTDI adapter.
I want to thank everyone for their help - I couldn't have do it (in this lifetime) without you!
I verified the bod is set to 4.3v, I was able to load my code and verified it worked as it should. Now off to test if all this effort was worth it! Hoping this stops the corrupting of the eeprom settings...
