How to use two SPI busses with CB1 on Manta M8P

[mykepredko]

Lots to go through here.

@limefrog

Hm,

according to this document:
BIGTREETECH MANTA M8P V1.1-SCH.pdf (3.2 MB)

The EXP2s SPI is connected to pins 50-53 of the STM32G0B1VET6 and it seems they are meant for an SD-card reader:

50 PB11/SPI2_MOSI,TIM2_CH4, USART3_RX, I2C2_SDA,ADC_IN15
51 SPI2_NSS/FDCAN2_RX,ADC_IN16/PB12
52 SPI2_SCK,TIM1_CH1N, FDCAN2_TX,I2C2_SCL/PB13PIU13052
53 SPI2_MISO/TIM15_CH1, I2C2_SDA/PB14 PIU13053

Those pins are the defaults for the SPI2 hardware port. In your printer.cfg you would be able to just specify SPI2.

Looking at the schematic (Manta M8P V1.1), these pins ONLY go to EXP2 - they do not go to the “MCU-CARD” (that’s the SPI1 pins discussed below).

@limefrog

That makes me think this refers in the end to /dev/spidev2.x but I really don’t know.

That’s using on the 40pin rPi connector.

@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.

@limefrog

@mykepredko

I agree that, at this point, you should separate your SPI devices and use separate SPI ports/pins for each device

At the moment the ADXL is NOT connected to the STM32, but connected to the 40-pin-GPIO connector of the CB1

19 PH7 	GPIO231, SPI1_MOSI
21 PH8 	GPIO232, SPI1_MISO
23 PH6 	GPIO230, SPI1_CLK 
26 PG8 	GPIO200, CS

I have it up and running there. So, according to ‘never touch a running system’ I’d keep it there. It is running on the seperate MCU

No worries, I’d agree with that.

@limefrog

@mykepredko

you have software SPI pins you can work with

Uw, this is a strange thing to me … connecting a wire to software sounds a bit like science-fiction. But I assume I can tell the software to accept hardware pins intended for other purposes to act as SPI bus pins?

It’s called “bit-banging” and a) very well understood and b) well implemented in Klipper.

But, what it appears to me is that you won’t need to use it.

@limefrog

@mykepredko

it would be helpful for you to list out what are the devices you want

• Steppers (X,Y,Z*3,E)
• Fans (coldend, partcooling*2, MCU)
• heaters (hotend, bed)
• temperature sensors (hotend, bed, MCU, chamber)
• LED Stripe (maybe a second one to visualise the state of the machine as a kind of traffic Light, later on)
• ADXL345 for resonance metering
• ADS1220 for Z-endstop via strain gauges/load-cells

Clean and compact. No display / touch screen. No CAN bus / I2C Bus. Only control element should be an ‘emergency stop button’ I didn’t manage to implement from first day.

Not what I was asking for - what I was asking about was the SPI devices you want to attach and which ones you want to use.

So, from what I understand, you have three SPI ports available:

• SPI1 which is the 8 pin connector on the M8P AND used for the motor connectors AND the SD Card socket (as noted above)
• SPI2 which is coming through the EXP2 connector
• rPi SPI /dev/spidev1.1 SPI port (which has your ADXL345 already on it)

That leaves the two SPI ports on the M8P for your use. If you are using SPI1 in any way (communicating with SPI TMC Stepper Drivers or using an SD Card for firmware updates) then I’d recommend staying away from it.

Now, above, you mention something about a TFT3.5 which uses an SPI interface -is this still an option?

@limefrog

Edit:

At the moment I’m convinced the EXP2 connector proposed by mykepredko seems to be the best choice…

…question is, how to implement it? How to figure out which micro-controller bus name has to be configured?

As noted above, it’s simply SPI2

@limefrog

Sadly the Klipper configuration reference isn’t helpful on this topic:

#spi_speed:
#   The SPI speed (in hz) to use when communicating with the device.
#   The default depends on the type of device.
#spi_bus:
#   If the micro-controller supports multiple SPI busses then one may
#   specify the micro-controller bus name here. The default depends on
#   the type of micro-controller.
#spi_software_sclk_pin:
#spi_software_mosi_pin:
#spi_software_miso_pin:
#   Specify the above parameters to use "software based SPI". This
#   mode does not require micro-controller hardware support (typically
#   any general purpose pins may be used). The default is to not use
#   "software spi".

spi_bus: spi2

I agree that the Klipper reference isn’t really helpful - I suspect that it has to do with the fact that main controller board designers are pretty willy-nilly when it comes to how SPI ports and pins are wired. However, it doesn’t look like the Manta M8P designer wasn’t too bad in selecting the SPI pins.

So, I think we’re in agreement that the SPI2 port would be best to wire the ADS1220.