76 lines
2.7 KiB
ReStructuredText
76 lines
2.7 KiB
ReStructuredText
Getting a MicroPython REPL prompt
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=================================
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REPL stands for Read Evaluate Print Loop, and is the name given to the
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interactive MicroPython prompt that you can access on your board through
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Zephyr. It is recommended to use REPL to test out your code and run commands.
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REPL over the serial port
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-------------------------
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The REPL is available on a UART serial peripheral specified for the board by
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the ``zephyr,console`` devicetree node. The baudrate of the REPL is 115200.
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If your board has a USB-serial converter on it then you should be able to access
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the REPL directly from your PC.
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To access the prompt over USB-serial you will need to use a terminal emulator
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program. For a Linux or Mac machine, open a terminal and run::
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screen /dev/ttyACM0 115200
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You can also try ``picocom`` or ``minicom`` instead of screen. You may have to use
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``/dev/ttyACM1`` or a higher number for ``ttyACM``. Additional permissions
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may be necessary to access this device (eg group ``uucp`` or ``dialout``, or use sudo).
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For Windows, get a terminal software, such as puTTY and connect via a serial session
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using the proper COM port.
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Using the REPL
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--------------
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With your serial program open (PuTTY, screen, picocom, etc) you may see a
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blank screen with a flashing cursor. Press Enter (or reset the board) and
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you should be presented with the following text::
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*** Booting Zephyr OS build zephyr-v3.1.0 ***
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MicroPython v1.19.1-9-g4fd54a475 on 2022-06-17; zephyr-frdm_k64f with mk64f12
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Type "help()" for more information.
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>>>
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Now you can try running MicroPython code directly on your board.
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Anything you type at the prompt, indicated by ``>>>``, will be executed after you press
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the Enter key. If there is an error with the text that you enter then an error
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message is printed.
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Start by typing the following at the prompt to make sure it is working::
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>>> print("hello world!")
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hello world!
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If you already know some python you can now try some basic commands here. For
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example::
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>>> 1 + 2
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3
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>>> 1 / 2
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0.5
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>>> 3 * 'Zephyr'
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ZephyrZephyrZephyr
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If your board has an LED, you can blink it using the following code::
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>>>import time
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>>>from machine import Pin
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>>>LED = Pin(("GPIO_1", 21), Pin.OUT)
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>>>while True:
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... LED.value(1)
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... time.sleep(0.5)
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... LED.value(0)
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... time.sleep(0.5)
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The above code uses an LED location for a FRDM-K64F board (port B, pin 21;
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following Zephyr conventions ports are identified by "GPIO_x", where *x*
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starts from 0). You will need to adjust it for another board using the board's
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reference materials.
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