Memo: EE - Boards | Raspi As MCU

(Feature image from Raspberry Pi Pinout)

Hardware Resources

References:

Raspberry Pi hardware - Raspberry Pi Documentation
- Searched by s3

Notes:

Overview

SPI

References:

树莓派（主）与STM32（从）使用SPI通信 - CSDN博客
- Searched by 树莓派 SPI 实验 in DDG
树莓派 wiringPi 用户手册 - 小鹏STEM
- Searched by 树莓派 3B SPI 实验 in DDG
Raspberry Pi Pinout Guide: How to use the Raspberry Pi GPIOs? - RNT
- Searched by raspberry pi 3B enable gpio in DDG
树莓派3B+ SPI Flash编程器 - 佐须之男的博客 - forgotfun.org
- Searched by s2 DDG
- Searched by in DDG

Notes:

System info:
- Board: Raspberry Pi 3B
- OS: Ubuntu Server 24.10
- Use ssh to connect the Raspberry Pi

Enable SPI interface (r1-CSDN)

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sudo apt-get install raspi-config
sudo raspi-config

Verify SPI is enabled:

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jack@Rpi:~$ ls /dev/spi*
/dev/spidev0.0  /dev/spidev0.1

GPIO pinout (r3-RNT):

SPI library on Raspberry Pi: wiringPi (r2-小鹏)

Lib Spidev

References:

Python驱动树莓派SPI接口 - 简书 - 月见樽
- Searched by 树莓派 3B SPI 实验 in DDG
Controlling an SPI device with the Raspberry Pi - Takaitra.com
- Refered by r1
doceme/py-spidev - GitHub
- Searched by `` in DDG
- Searched by `` in DDG

Notes:

(2024-10-31)

SPI library for Python: py-spidev

Compile py-spidev from source code (r2-Takaitra)

Installed python3-dev ahead.
Use python3 instead of python by setting the env ${PYTHON}.

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jack@Rpi:~$ cd Programs/py-spidev/

jack@Rpi:~/Programs/py-spidev$ make
python setup.py build
make: python: No such file or directory
make: *** [Makefile:4: all] Error 127

jack@Rpi:~/Programs/py-spidev$ ls
CHANGELOG.md  MANIFEST.in  README.md  setup.py
LICENSE       Makefile     setup.cfg  spidev_module.c

jack@Rpi:~/Programs/py-spidev$ cat Makefile
PYTHON ?= python

all:
        $(PYTHON) setup.py build

install:
        $(PYTHON) setup.py install

clean:
        $(PYTHON) setup.py clean
        rm -rf build dist

cleandir distclean: clean
        $(PYTHON) setup.py clean -a


jack@Rpi:~/Programs/py-spidev$ echo ${PYTHON}

jack@Rpi:~/Programs/py-spidev$ export PYTHON='python3'

jack@Rpi:~/Programs/py-spidev$ echo ${PYTHON}
python3

Error: gcc missed

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jack@Rpi:~/Programs/py-spidev$ make
python3 setup.py build
/usr/lib/python3/dist-packages/setuptools/dist.py:452: SetuptoolsDeprecationWarning: Invalid dash-separated options
!!

        ********************************************************************************
        Usage of dash-separated 'description-file' will not be supported in future
        versions. Please use the underscore name 'description_file' instead.

        This deprecation is overdue, please update your project and remove deprecated
        calls to avoid build errors in the future.

        See https://setuptools.pypa.io/en/latest/userguide/declarative_config.html for details.
        ********************************************************************************

!!
  opt = self.warn_dash_deprecation(opt, section)
running build
running build_ext
building 'spidev' extension
creating build
creating build/temp.linux-aarch64-cpython-312
aarch64-linux-gnu-gcc -fno-strict-overflow -Wsign-compare -DNDEBUG -g -O2 -Wall -fPIC -I/usr/include/python3.12 -c spidev_module.c -o build/temp.linux-aarch64-cpython-312/spidev_module.o
error: command 'aarch64-linux-gnu-gcc' failed: No such file or directory
make: *** [Makefile:4: all] Error 1

Have use apt-file serach aarch64-linux-gnu-gcc, which lists many packages.

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jack@Rpi:~/Programs/py-spidev$ apt-file search aarch64-linux-gnu-gcc
gcc-11: /usr/bin/aarch64-linux-gnu-gcc-11
gcc-11: /usr/bin/aarch64-linux-gnu-gcc-ar-11
gcc-11: /usr/bin/aarch64-linux-gnu-gcc-nm-11
...

Need to install gcc, the default version is 14

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jack@Rpi:~/Programs/py-spidev$ dpkg -l gcc
dpkg-query: no packages found matching gcc

jack@Rpi:~/Programs/py-spidev$ gcc -v
Command 'gcc' not found, but can be installed with:
sudo apt install gcc

jack@Rpi:~/Programs/py-spidev$ sudo apt install gcc
Installing:
  gcc

Installing dependencies:
  cpp                       gcc-14-aarch64-linux-gnu  libhwasan0  libtsan2
  cpp-14                    gcc-aarch64-linux-gnu     libisl23    libubsan1
  cpp-14-aarch64-linux-gnu  libasan8                  libitm1
  cpp-aarch64-linux-gnu     libcc1-0                  liblsan0
  gcc-14                    libgcc-14-dev             libmpc3

Suggested packages:
  cpp-doc         gcc-multilib  libtool  gdb         gdb-aarch64-linux-gnu
  gcc-14-locales  autoconf      flex     gcc-doc
  cpp-14-doc      automake      bison    gcc-14-doc

Summary:
  Upgrading: 0, Installing: 18, Removing: 0, Not Upgrading: 2
  Download size: 45.1 MB
  Space needed: 148 MB / 57.1 GB available

Continue? [Y/n]

...

jack@Rpi:~/Programs/py-spidev$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/aarch64-linux-gnu/14/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: aarch64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 14.2.0-4ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-14/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2,rust --prefix=/usr --with-gcc-major-version-only --program-suffix=-14 --program-prefix=aarch64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/libexec --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-libstdcxx-backtrace --enable-gnu-unique-object --disable-libquadmath --disable-libquadmath-support --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --enable-fix-cortex-a53-843419 --disable-werror --enable-offload-targets=nvptx-none=/build/gcc-14-T7YiXd/gcc-14-14.2.0/debian/tmp-nvptx/usr --enable-offload-defaulted --without-cuda-driver --enable-checking=release --build=aarch64-linux-gnu --host=aarch64-linux-gnu --target=aarch64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 14.2.0 (Ubuntu 14.2.0-4ubuntu2)

After make succeeded, sudo make install executes setup.py where python appears as well.

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jack@Rpi:~/Programs/py-spidev$ sudo make install
python setup.py install
make: python: No such file or directory
make: *** [Makefile:7: install] Error 127

jack@Rpi:~/Programs/py-spidev$ echo ${PYTHON}
python3

jack@Rpi:~/Programs/py-spidev$ cat -n Makefile | sed -n 1,7p
     1  PYTHON ?= python
     2
     3  all:
     4          $(PYTHON) setup.py build
     5
     6  install:
     7          $(PYTHON) setup.py install

I saw the fist line of setup.py is #!/usr/bin/env python, so I suspected the python here also needs to “remap” to python3.

Create an alias python for python3 doesn’t work for the ``

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jack@Rpi:~/Programs/py-spidev$ sudo apt install neovim
jack@Rpi:~/Programs/py-spidev$ nvim ~/.bashrc

Append a command at the end of the ~/.bashrc:

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# (2024-10-31)
alias python="python3"

Still cannot override python even I have set the environment variable:

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jack@Rpi:~/Programs/py-spidev$ export PYTHON='python3'

jack@Rpi:~/Programs/py-spidev$ sudo make install
python setup.py install
make: python: No such file or directory
make: *** [Makefile:7: install] Error 127

jack@Rpi:~/Programs/py-spidev$ echo ${PYTHON}
python3

However, sudo make install PYTHON=python3 works, as suggested by ChatGPT.

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...
Processing spidev-3.6-py3.12-linux-aarch64.egg
creating /usr/local/lib/python3.12/dist-packages/spidev-3.6-py3.12-linux-aarch64.egg
Extracting spidev-3.6-py3.12-linux-aarch64.egg to /usr/local/lib/python3.12/dist-packages
Adding spidev 3.6 to easy-install.pth file

Installed /usr/local/lib/python3.12/dist-packages/spidev-3.6-py3.12-linux-aarch64.egg
Processing dependencies for spidev==3.6

Demo Code

(2024-11-01)

Code: “spi_test.py” (r2-Takaitra)

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import spidev
import time

spi = spidev.SpiDev()
spi.open(0, 0)   # arguments: (bus, device), i.e., (SPI0, CS0)
spi.max_speed_hz = 7629
spi.mode = 0b01  # [CPOL | CPHA]

# Split an integer input into a two byte array to send via SPI
def write_pot(input):
    msb = input >> 8     # Shift the higher 8 bits to the lower half
    lsb = input & 0xFF   # Only keep the lower 8 bits
    spi.xfer([msb, lsb])

# Repeatedly switch a MCP4151 digital pot off then on
while True:
    write_pot(0x1FF)
    time.sleep(0.5)
    write_pot(0x00)
    time.sleep(0.5)

Execute this script, the program will keep running forever:

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python3 spi_test.py

Pinout

References:

Raspberry Pi hardware - Raspberry Pi Documentation
- Searched by raspberry pi 3B pinout in DDG
Raspberry Pi Pinout
- Searched by 树莓派3D 串口实验 in bilibili
- Searched by in DDG

Notes:

(2024-11-01)

Check pinout with command pinout

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sudo apt install python3-gpiozero
pinout

(2024-11-29)

The serial (TX and RX) on Model 3B are turned off by default, because they are occupied by the Bluetooth ^r2-bilibili.

UART

Comm With Arduino

References:

How to read data through UART - Raspberry Pi Forums
- Searched by raspberry pi uart receive and display on terminal in Google
树莓派4 UART 多串口配置通信 | 树莓派实验室
- Searched by 树莓派 UART in Google
UART配置- 树莓派中文文档
- Searched by in s2
- Searched by in DDG

Notes:

(2024-11-29)

Arduino: Serial.write(), and Raspberry Pi print the received message in terminal ^r1-Forum.

(2024-12-05)

The pin: TX1 and RX0 both are 5V, whereas the UART on Rpi is 3.3V. So they cannot connect directly ^r3-Hackpi.

Table of contents

Hardware Resources

SPI

Lib Spidev

Demo Code

Pinout

UART

Comm With Arduino