85 lines
2.4 KiB
Markdown
85 lines
2.4 KiB
Markdown
---
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id: dev-guide-usb-logging
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title: USB Logging
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---
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import Tabs from '@theme/Tabs';
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import TabItem from '@theme/TabItem';
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## Overview
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If you are developing ZMK on a device that does not have a built in UART for debugging and log/console output,
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Zephyr can be configured to create a USB CDC ACM device and the direct all `printk`, console output, and log
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messages to that device instead.
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:::warning Battery Life Impact
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Enabling logging increases the power usage of your keyboard, and can have a non-trivial impact to your time on battery.
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It is recommended to only enable logging when needed, and not leaving it on by default.
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:::
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## Kconfig
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The following KConfig values need to be set, either by copy and pasting into the `app/prj.conf` file, or by running
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`west build -t menuconfig` and manually enabling the various settings in that UI.
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```
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# Turn on logging, and set ZMK logging to debug output
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CONFIG_LOG=y
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CONFIG_ZMK_LOG_LEVEL_DBG=y
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# Turn on USB CDC ACM device
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CONFIG_USB=y
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CONFIG_USB_DEVICE_STACK=y
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CONFIG_USB_CDC_ACM=y
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CONFIG_USB_CDC_ACM_RINGBUF_SIZE=1024
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CONFIG_USB_CDC_ACM_DEVICE_NAME="CDC_ACM"
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CONFIG_USB_CDC_ACM_DEVICE_COUNT=1
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# Enable serial console
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CONFIG_SERIAL=y
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CONFIG_CONSOLE=y
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CONFIG_UART_INTERRUPT_DRIVEN=y
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CONFIG_UART_LINE_CTRL=y
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# Enable USB UART, and set the console device
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CONFIG_UART_CONSOLE=y
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CONFIG_USB_UART_CONSOLE=y
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CONFIG_UART_CONSOLE_ON_DEV_NAME="CDC_ACM_0"
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CONFIG_USB_UART_DTR_WAIT=n
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```
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## Viewing Logs
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After flashing the updated ZMK image, the board should expose a USB CDC ACM device that you can connect to and view the logs.
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<Tabs
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defaultValue="linux"
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values={[
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{label: 'Linux', value: 'linux'},
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{label: 'Windows', value: 'win'},
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]}>
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<TabItem value="linux">
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On Linux, this should be a device like `/dev/ttyACM0` and you can connect with `minicom` or `tio` as usual, e.g.:
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```
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sudo tio /dev/ttyACM0
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```
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</TabItem>
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<TabItem value="win">
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On Windows, you can use [PuTTY](https://www.putty.org/). Once installed, use Device Manager to figure out which COM port your controller is communicating on (listed under 'Ports (COM & LPT)') and specify that as the 'Serial line' in PuTTY.
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If you already have the Ardunio IDE installed you can also use its built-in Serial Monitor.
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</TabItem>
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</Tabs>
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From there, you should see the various log messages from ZMK and Zephyr, depending on which systems you have set to what log levels.
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