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75 lines
2.6 KiB
Markdown
75 lines
2.6 KiB
Markdown
This document describes Klipper's CAN bus support.
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# Device Hardware
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Klipper currently only supports CAN on stm32 chips. In addition, the
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micro-controller chip must support CAN and it must be on a board that
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has a CAN transceiver.
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To compile for CAN, run "make menuconfig", unselect "Use USB for
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communication (instead of serial)" and then select "Use CAN for
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communication (instead of serial)". Finally, compile the
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micro-controller code and flash it to the target board.
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# Host Hardware
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In order to use a CAN bus, it is necessary to have a host adapter.
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There are currently two common options:
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1. Use a [Waveshare Raspberry Pi CAN
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hat](https://www.waveshare.com/rs485-can-hat.htm) or one of its
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many clones.
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2. Use a USB CAN adapter (for example
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[https://hacker-gadgets.com/product/cantact-usb-can-adapter/](https://hacker-gadgets.com/product/cantact-usb-can-adapter/)). There
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are many different USB to CAN adapters available - when choosing
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one, we recommend verifying it can run the [candlelight
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firmware](https://github.com/candle-usb/candleLight_fw). (Unfortunately,
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we've found some USB adapters run defective firmware and are locked
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down, so verify before purchasing.)
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It is also necessary to configure the host operating system to use the
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adapter. This is typically done by creating a new file named
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`/etc/network/interfaces.d/can0` with the following contents:
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```
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auto can0
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iface can0 can static
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bitrate 500000
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up ifconfig $IFACE txqueuelen 128
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```
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Note that the "Raspberry Pi CAN hat" also requires [changes to
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config.txt](https://www.waveshare.com/wiki/RS485_CAN_HAT).
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# Finding the canbus_uuid for new micro-controllers
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Each micro-controller on the CAN bus is assigned a unique id based on
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the factory chip identifier encoded into each micro-controller. To
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find each micro-controller device id, make sure the hardware is
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powered and wired correctly, and then run:
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```
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~/klippy-env/bin/python ~/klipper/scripts/canbus_query.py can0
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```
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If uninitialized CAN devices are detected the above command will
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report lines like the following:
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```
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Found canbus_uuid=11aa22bb33cc
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```
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Each device will have a unique identifier. In the above example,
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`11aa22bb33cc` is the micro-controller's "canbus_uuid".
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Note that the `canbus_query.py` tool will only report uninitialized
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devices - if Klipper (or a similar tool) configures the device then it
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will no longer appear in the list.
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# Configuring Klipper
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Update the Klipper [mcu configuration](Config_Reference.md#mcu) to use
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the CAN bus to communicate with the device - for example:
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```
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[mcu my_can_mcu]
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canbus_uuid: 11aa22bb33cc
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```
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