Strange behavior of ADXL345 - in search for a reliable alternative

[mykepredko]

@limefrog

to answer your question, i ’d like to refer to our discussion one year ago :

That was a long involved discussion a while ago and quite a bit of water has passed under the bridge since then.

Going over it again, I don’t think I’m contradicting myself here - if you look through the post you’re listing:

@mykepredko

@limefrog

I also discovered the 8-pin connector called SPI (P6) being connected to:

30 PIU13030 PA5/SPI1_SCK/I2S1_CK,USART6_RX, USART3_TX,ADC12_IN5
31 PIU13031 PA6/SPI1_MISO/TIM3_CH1,TIM16_CH1,I2C2_SDA,I2C3_SDA/ADC_IN6
32 PIU13032 PA7/SPI1_MOSI/TIM3_CH2,I2C2_SCL,I2C3_SCL/ADC_IN7
33 PIU13033 PC4/USART3_TX, USART1_TX, TIM2_CH1_ETR, FDCAN1_RX/ADC_IN17

That is the default for SPI1

@limefrog

This SPI bus seems to be connected to the stepper drivers also, so I think, it is not a good idea to wire the ADXL here due to its behavior with other devices. But the ADS1220 might be possible?

What are the stepper drivers that you’re using. If you’re not using the TMC2130/TMC2160 (ie TMC2208 or TMC2209) then you’re fine.

I guess it’s not completely explicit but I was saying that you can use SPI1 for the ADXL345 - what I’m recommending here. At the time I did not know (you hadn’t decided) which stepper drivers you were using so I put in the caveat that if you’re using stepper drivers that use an SPI port you should use something other than SPI1 on the P6 connector.

Going through your klippy.log, I saw that you are using TMC2209s for all your stepper motor drivers so, using P6 and SPI1 (like I suggested in my original reply) should not have a problem and, in my opinion, should be more reliable than using the bit banging port software of spidev

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When I talked about my usage, I noted that I use the integrated ADXL345 on the EBB42 when I have a toolhead stepper motor. I also use the small ADXL345 boards (from Amazon/AliExpress), connected to an SPI port on the main controller board and zip-tied to the toolhead for resonance measurements:

Again, I’ve never had any issues with ADXL345s but I do connect them to a controller board’s SPI port and not an SBC’s GPIO pins.