118 lines
5.5 KiB
Markdown
118 lines
5.5 KiB
Markdown
# Serial
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The [serial](/reference/serial) supports [serial communication](https://en.wikipedia.org/wiki/Serial_port) between the BBC micro:bit and another computer. Basically, this allows you to send data from the micro:bit to your own computer. This is very useful for debugging purposes: you can add `write line` statements in your code and see them display on your computer as the program executes.
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The code below shows a simple script that sends a line when the BBC micro:bit starts and another line each time the button ``A`` is pressed.
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```blocks
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serial.writeLine("started...")
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input.onButtonPressed(Button.A, () => {
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serial.writeLine("A pressed")
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})
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```
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Data is also automatically streamed to serial by the ** bar graph** block
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and picked up by the editor. This data can be streamed to the cloud as well.
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```blocks
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basic.forever(() => {
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led.plotBarGraph(input.acceleration(Dimension.X), 0);
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});
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```
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## How to read the micro:bit's serial output from your computer
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Unfortunately, using the serial library requires quite a bit of a setup.
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### ~ hint
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**Windows earlier than 10**
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If you are running a Windows version earlier than 10, you must install a device driver
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(for the computer to recognize the serial interface of the micro:bit).
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* Follow the instructions at https://docs.mbed.com/docs/mbed-os-handbook/en/latest/getting_started/what_need/ to install the device driver.
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### ~
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### Chrome Extension
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If you are using the Google Chrome browser, you can use our extension to get serial data streaming in the editor.
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* Install the [Extension for micro:bit](https://chrome.google.com/webstore/detail/extension-for-bbc-microbi/cihhkhnngbjlhahcfmhekmbnnjcjdbge?hl=en-US) on the Chrome Web Store.
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* Restart Chrome and open the [web editor](@homeurl@)
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* The serial data will show below the simulator
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If the extension is enabled, it will not be possible to access the port/device for the micro:bit from other programs than Chrome.
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### Windows > Tera Term
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* Install the terminal emulator [Tera Term](https://ttssh2.osdn.jp/index.html.en). At the time of this writing, the latest version is 4.88 and can be downloaded [from here](http://en.osdn.jp/frs/redir.php?m=jaist&f=%2Fttssh2%2F63767%2Fteraterm-4.88.exe). Follow the instructions from the installer.
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Once both the driver and the terminal emulator are installed, plug in the micro:bit and wait until the device is fully setup. Then, open TeraTerm.
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* Hit `File` > `New Connection`
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* Check "Serial"; in the dropdown menu, pick the COM port that says "mbed Serial Port". Hit `Ok`.
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* In the menus, hit `Setup` > `Serial Port` and set the baud rate to `115200`.
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You should be good. Feel free to hit `Setup` > `Save Setup` in the menus to erase the default configuration file with a new one so that you don't have to type in the settings again.
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Please note that Windows will assign you a different COM port if you plug in another micro:bit. If you're juggling between micro:bits, you'll have to change the COM port every time.
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### Windows > Putty
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If you prefer another terminal emulator (such as [PuTTY](http://www.putty.org/)), here are some instructions.
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* Open Windows's [Device Manager](https://windows.microsoft.com/en-us/windows/open-device-manager); expand the section called "Ports (COM & LPT)"; write down the com number for "mbed Serial Port" (e.g. COM14)
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* Open PuTTY; on the main screen, use the following settings: Serial / COM14 / 115200. Replace COM14 with the COM port number you wrote down previously. Feel free to type in a name and hit "Save" to remember this configuration.
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* (optional): in the "Terminal" section, check "implicit cr in every lf"
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### Linux
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* Install the program `screen` if it is not already installed.
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* Plug in the micro:bit.
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* Open a terminal.
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* Find which device node the micro:bit was assigned to with the command `ls /dev/ttyACM*`.
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* If it was `/dev/ttyACM0`, type the command `screen /dev/ttyACM0 115200`. If it was some other device node,
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use that one in the command instead. **Note:** You may need root access to run `screen`
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successfully. You can probably use the command `sudo` like this: `sudo screen /dev/ttyACM0 115200`.
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* To exit `screen`, type `Ctrl-A` `Ctrl-D`.
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Alternative programs include `minicom` and so on.
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### Mac OS
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* Plug in the micro:bit
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* Open a terminal
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* `ls /dev/cu.*` will return to you a list of serial devices; one of them will look like `/dev/cu.usbmodem1422` (the exact number depends on your computer)
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* `screen /dev/cu.usbmodem1422 115200` will open up the micro:bit's serial output. To exit, hit `Ctrl-A` `Ctrl-D`.
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### Custom Chrome Extensions
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### ~ hint
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**Developer Zone!** This is an experimental feature that may change in the future and requires understanding how to [build Chrome Extensions](https://developer.chrome.com/extensions/getstarted).
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### ~
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You can use the ``chromeserial=CHROMEID`` query argument to load your own Chrome Extension in the editor. You can find the ChromeID in the list of extensions or the store URL.
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* see the sources of the [micro:bit extension](https://github.com/Microsoft/pxt-microbit/blob/master/clients/chrome/background.ts)
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* the editor will try to connect a port named ``serial`` ([source](https://github.com/Microsoft/pxt-microbit/blob/master/clients/chrome/background.ts#L73))
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* data can be sent back to the editor as JSON payloads ([source](https://github.com/Microsoft/pxt-microbit/blob/master/clients/chrome/background.ts#L42))
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```typescript-ignore
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port.postMessage({
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type: "serial",
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data: decodedString,
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id: id
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}));
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}
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``` |