HowTo update ATMega?

[thymjan]

I'm wondering how to update the ATMega.
Which pins are used for this?

[4tronix]

Hi, This is covered in the readme file https://github.com/4tronix/PiconZero

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On 1 Jun 2018, at 19:04, Stefan Theurer ***@***.***> wrote: I'm wondering how to update the ATMega. Which pins are used for this? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or mute the thread.

[thymjan]

Wow! Thank you for the fast answer. I've read the readme file, but I wonder where I can find those pins on the board. They are not marked, are they?

[thymjan]

Maybe these?

[4tronix]

Yes you’re correct. This is v1.3

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On 1 Jun 2018, at 19:31, Stefan Theurer ***@***.***> wrote: Maybe these? — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[thymjan]

My board is marked with v1.0, but the pinholes looks the same.
So it's like this:

Do I have to isolate the board or can I leave it stuck on the raspberry for programming? Should it be powered in an additional way or only with this vcc pin?

[thymjan]

Now I've put the new sketch on the ATMega on my PiconZero board. Was a bit unsure, but it worked flawlessly. And: it worked on the fly, I could do this like a boxing stop with my rover powered on.
I didn't have a USB to Serial converter with 5V so I took my Arduino Uno and removed its ATMega:

Here are the connections:

Uno -> PiconZero
---------------------
GND (black) -> GND
5V (orange) -> VCC
0 RX (green) -> TXD
1 TX (yellow) -> RXD
RESET (white) -> DTR

In the Arduino-IDE I choosed "Arduino/Genuino UNO" as Board. Then I compiled the PiconZero10.ino sketch and uploaded it. I had to reboot my raspberry pi zero w once, because the servos didn't work. After the reboot everything worked well.

[Workshopshed]

Great work Stefan, I've been following along. Why did you want to update the firmware? Was it simply you had an old board?

[thymjan]

I’m struggling around with reboots of my raspberry pi zero while driving. Sometimes more, sometimes less. I’ve just one battery, I know this is a difficult setup.
I’ve read the PWM structure was modified with Version 10 (mine was 8). So I wanted to give it a try. The traction is even better now, but my investigations show the need for more energy.
Maybe I switch to a two battery solution now.

[Workshopshed]

The reboots could be caused by brownouts i.e. too much current being taken from the supply. If the power requirements are very bursty then a big capacitor across the supply might be a solution otherwise separate power for the Pi and motor should work