115 lines
4.0 KiB
Markdown
115 lines
4.0 KiB
Markdown
MicroPython port to Zephyr RTOS
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===============================
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This is an initial port of MicroPython to Zephyr RTOS
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(http://zephyrproject.org).
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The port integrates well with Zephyr build system, using the latest
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features which will be available in 1.6.0, and thus requires Zephyr
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master to build against. All boards supported by Zephyr (with standard
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level of feature support, like UART console) should work with
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MicroPython (but not all were tested).
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Features supported at this time:
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* REPL (interactive prompt) over Zephyr UART console.
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* `utime` module for time measurements and delays.
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* `machine.Pin` class for GPIO control.
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* "Frozen modules" support to allow to bundle Python modules together
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with firmware. Including complete applications, including with
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run-on-boot capability.
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Over time, bindings for various Zephyr subsystems may be added.
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Building
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--------
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Follow to Zephyr web site for Getting Started instruction of installing
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Zephyr SDK, getting Zephyr source code, and setting up development
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environment. (Direct link:
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https://www.zephyrproject.org/doc/getting_started/getting_started.html).
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You may want to build Zephyr's own sample applications to make sure your
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setup is correct.
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To build MicroPython port, in the port subdirectory (zephyr/), run:
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make BOARD=<board>
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If you don't specify BOARD, the default is `qemu_x86` (x86 target running
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in QEMU emulator). Consult Zephyr documentation above for the list of
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supported boards.
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Running
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-------
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To run the resulting firmware in QEMU (for BOARDs like qemu_x86,
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qemu_cortex_m3):
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make qemu
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With the default configuration, networking is now enabled, so you need to
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follow instructions in https://wiki.zephyrproject.org/view/Networking-with-Qemu
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to setup host side of TAP/SLIP networking. If you get error like:
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could not connect serial device to character backend 'unix:/tmp/slip.sock'
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it's a sign that you didn't followed instructions above. If you would like
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to just run it quickly without extra setup, see "minimal" build below.
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For deploying/flashing a firmware on a real board, follow Zephyr
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documentation for a given board, including known issues for that board
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(if any). (Mind again that networking is enabled for the default build,
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so you should know if there're any special requirements in that regard,
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cf. for example QEMU networking requirements above; real hardware boards
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generally should not have any special requirements, unless there're known
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issues).
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Quick example
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-------------
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To blink an LED:
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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 port are identified by "GPIO_x", where *x*
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starts from 0). You will need to adjust it for another board (using board's
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reference materials). To execute the above sample, copy it to clipboard, in
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MicroPython REPL enter "paste mode" using Ctrl+E, paste clipboard, press
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Ctrl+D to finish paste mode and start execution.
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Minimal build
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-------------
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MicroPython is committed to maintain minimal binary size for Zephyr port
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below 128KB, as long as Zephyr project is committed to maintain stable
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minimal size of their kernel (which they appear to be). Note that at such
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size, there is no support for any Zephyr features beyond REPL over UART,
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and only very minimal set of builtin Python modules. Thus, this build
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is more suitable for code size control and quick demonstrations even on
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smaller systems. It's also suitable for careful enabling of features one
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by one to achieve needed functionality and code size. This is in contrast
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to the "default" build, which may get more and more features enabled by
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default over time.
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To make a minimal build:
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make BOARD=<board> minimal
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To run a minimal build in QEMU without requiring TAP networking setup
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run the following after you built image with the previous command:
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make BOARD=<qemu_x86|qemu_cortex_m3> qemu-minimal
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