[Solved / Archived] Witty Pi 4 L3V7 I2C read 0x01 0x08 61 failed (result=), and no more retry.

Better to check the physical connection first. If SDA, SCL or GND is not well connected, your Pi can not detect the I2C device with address 0x08.

Hi

Thanks for your input. Your Hat is sitting flush with the RPi board. I have confirmed the screws holding it down have n0t come loose.  This is the 4th unit I had doing this to me.  I have returned and exhanged 3 of them.  But, as this has now happened on the 4th unit I am concerned that this HAT is inreliable for my commercial product. Everything I use is secured and screwed down.  I think this board you people have developed is fantastic. I would love a fix to this problem.  What else can cause this issue?

Thanks

The iights are on this HAT.  Is it possible that the firmware needs to be reflashed?

In such case, check if the firmware is still there and working. Just power the HAT (without Raspberry Pi) and tap the button, and see if the red LED on board lights up.

If it doesn't, that means the firmware is gone, and this might be due to over-discharged of battery (and extremely low voltage fed to Witty Pi 4 L3V7, which can't make the MCU ATtiny841 fully working). In such case you will have to reflash the firmware.

Hi, as stated in my last message, the lights are all on. So, reflashing would not work I guess.  

"extremely low voltage fed to Witty Pi 4 L3V7"

There is in the flash setting that if there is a low voltage to turn off immediately. 

So, I am guessing that is it? As I mentioned intially, this has happened 3 other times.  So, it looks like I cannot rely on this unit and wil have to return all stock to the reseller then 🙁 Sorry to go through all this with you. I know you are doing your best to help me. When I return the stock they like to see if I have tried to resolve this with uugear before they wil accept a return. I was going to suggest reflashing depsite the lights being on to see if that would work.  Despite the lights being on I can still give that a go if you can provide instructions to me? Just to rule it in or out. 

Thanks for replying on the weekend, much appreciated.  

@andrew-simpson17 The board comes with a default setting that disallows the battery to get discharged under 3.1V. That's the default low-voltage threshold. With such configuration, when battery is about to used up, the system will be shut down instead.

However, if user remove this setting, or set it to too low, it will not be able to protect the board and the battery then.

Even if the configuration is still there, what if the battery's voltage drops too quickly? In such case there will be no enough time to do the proper shutdown, and the MCU may be forced to work under voltage like 2.4V or something, which could cause all kinds of problem. When using small battery, such situation has higher chance to happen.

We recently realized that the better way is to turn on the built-in B.O.D. mechanism in ATtiny841. This is done by setting the correct fuses in IDE. The link is to a picture of how to configure the fuses in Arduino IDE. If you search in the forum, you can find more information about how to flash the firmware.

Next week I will write a detailed tutorial about how to update firmware in Witty Pi 4 (Mini/L3V7), maybe you can wait for that.

"However, if user remove this setting, or set it to too low, it will not be able to protect the board and the battery then."
OK. But I have not touched this.

"When using small battery, such situation has higher chance to happen."
I have a 20,000mHa battery atttached and a 100mHA lipo battery attached. So, am i right in assuming that this cannot happen as the lipo battery woudl always be fully charged?

"We recently realized that the better way is to turn on the built-in B.O.D. mechanism in ATtiny841. This is done by setting the correct fuses in IDE. The link is to a picture of how to configure the fuses in Arduino IDE. If you search in the forum, you can find more information about how to flash the firmware."
You lost me there. Total novice. I just write software 🙂
However, I will do a search to see if it makes sense to me 🙂

"Next week I will write a detailed tutorial about how to update firmware in Witty Pi 4 (Mini/L3V7), maybe you can wait for tha"
That would be very useful. I am not ready to give up on this unit. I have them in over 60 cameras sold and have 500 in stock you see.

thanks for all your time 🙂

"he link is to a picture of how to configure the fuses in Arduino IDE."

No link?

Sorry,missed the link.  Viewed it. How do I implement it?

Sorry, should of read things better.  Wish I could delete illogical statements I made.

So, do I need a Arduino? I also have never used the Arduino IDE. I use higher level C# ide. Will your instructions next week show me how to do this (i.e. an idiots guide)?.

I have ordered bigger capacity LIPO batteries to make sure that a sudden lose of power (if that 100mHa has lost its charge for some reason).  My settings are that if the LIPO battery falls below 4V and the delay to shutdown is 25 seconds to allow my service on the Rpi Zero 2 to shutdown properly before main power is cut.  If there is anything I need to be mindful with that configuration please advise.

Apart from that enjoy the rest of your weekend.. 

@andrew-simpson17 You don't need Arduino if you just want to reflash the firmware. There are precompiled firmware on our GitHub repository and you just need to flash it into the board with avrdude command. Having a USBasp programmer would be nice, but also not necessary: you may use Dopont wires to connect the 6-pin programing header to your Raspberry Pi's GPIO header, and use Raspberry Pi as a programmer. I will put details in my tutorial.

If you want to modify and compile the firmware by yourself, you will then need to use Arduino IDE. I will also cover this aspect in my tutorial.

You mentioned that you have returned and exchanged 3 units of Witty Pi 4 L3V7, I have to say that's quite unusual. I know Witty Pi 4 L3V7 is not that fragile, actually it never failed in our laboratory and the complains from customer is rather rare. We did receive some reports about losing some EEPROM data (specifictly the first byte in EEPROM, which makes the software unable to recognize it as L3V7 and instead treats it as normal Witty Pi 4), and our investigation result points to the requirement of turning on B.O.D., which we did recently. However it will take some time to spawn to products in stock. At the moment the quickest way to turn on B.O.D. is to flash the firmware with proper fuse settings, which I will introduce in my tutorial too.

Back to your case, the same problem keeps happening, so something unsual must have happened. It would be better that you tell us how you connect battery to the board. The board has only one battery connector, but you mentioned that you have "a 20,000mHa battery atttached and a 100mHA lipo battery attached", how did you do that? It would be even better if you provide a picture, or a drawing of the wiring.

Hi

Thanks very much for such a detailed reply.

[You don't need Arduino if you just want to reflash the firmware]
OK

[I will also cover this aspect in my tutorial.]
Great

[I know Witty Pi 4 L3V7 is not that fragile, actually it never failed in our laboratory and the complains from customer is rather rare.]
I am glad the error must be on my side then. Means it is solvable.

[flash the firmware with proper fuse settings, which I will introduce in my tutorial too.]
Thanks

[It would be better that you tell us how you connect battery to the board.]
[how did you do that? It would be even better if you provide a picture, or a drawing of the wiring.]
Not sure why this is confusing? 🙂

@andrew-simpson17 my confusion comes from:

Posted by: @andrew-simpson17

↑

I have a 20,000mHa battery atttached and a 100mHA lipo battery attached.

Did you mean you connected two batteries to one device? Or you mean two batteries for two devices?

BTW, if you use only a 100mAh battery for Witty Pi 4 L3V7, that will be definitely not enough and your Pi will lose power immediately when USB power supply is disconnected.

The 20,000mHa usb power bank i attached to the USB-C port. The 100mHa LIPO battery is connected to the LIPO port. Your HAT has been configured to act as a UPS with the configuration settings i have already mentioned.

Of course the 100mHA battery as the main power source woud not be enough. 

As soon as the USB PowerBank has been removed or discharged completely, the 100mHa wil 'kick in' and the RPi will go into standby after 25 seconds. The 100mHa is just to aide a graceful shutdown and not run any application longer than 25 seconds