[WIP] screw_drive_unit_pico

Code for Controlling Screw-Drive Unit by Using Raspberry Pi Pico, URL: https://www.raspberrypi.com/products/raspberry-pi-pico/

Environment Configuration

Install build tools

sudo apt-get install cmake gcc-arm-none-eabi libnewlib-arm-none-eabi build-essential
sudo apt-get install pkg-config libusb-1.0-0-dev

Get the source with the following directory structure:

~/screw_drive_unit_pico/
  pico-sdk/
  pico-examples/
  screw_drive_unit_pico/

Update submodules

git submodule update --init
cd pico-sdk
git submodule update --init

Set up the user environment variable, and modify $HOME with the path of the repository:

cd ~
echo "export PICO_SDK_PATH=$HOME/screw_drive_unit_pico/pico-sdk" >> ~/.bashrc
. ~/.bashrc

How to build

cd ~/screw_drive_unit_pico/screw_drive_unit_pico
mkdir build
cd build
cmake .. -DPICO_BOARD=pico_w -DCMAKE_BUILD_TYPE=Release
make

How to load program

1. Hold down the BOOTSEL button on your Pico-series device while plugging it into your development device using a micro USB cable to force it into USB Mass Storage Mode.
2. Copy main.uf2 in build folder into the USB Mass Storage Mode.

Pico-CAN-B from WaveShare

Website: https://www.waveshare.com/wiki/Pico-CAN-B

CAN Message Frame

App	msg[0]	msg[1]	msg[2]	msg[3]	msg[4~7]
frame structure	header	header	Instruction	Register	Data(uint32_t): msg[4]=L ~ msg[7]=H

Instruction

Value	Insruction	Description
0x02	Read	Instruction to read data from the Device
0x03	Write	Instruction to write data on the Device

Protocol

R/W	Register	Data
R	0x01	unique board ID
R/W	0x02	Unit CAN ID: Standard ID(uint16_t): msg[6]=High 8 bits, msg[7]=L 3 bits
R/W	0x03	LED Enable/Disable
R/W	0x04	LED Status, On: 1, Off: 0
R/W	0x05	Motor Command
R/W	0x06	Joint 1 Command
R/W	0x07	Joint 2 Command
R/W	0x08	Joint 1 Torque Enable
R/W	0x09	Joint 2 Torque Enable

Flash Register Address

Pico has a 2MB flash starting from address 0x10000000.

R/W	Register	Data
R/W	0x10000000	Unit CAN ID: High 8 bits
R/W	0x10000001	Unit CAN ID: Low 3 bits

Some Tools for Development

Serial Port Assistant

https://github.com/KangLin/SerialPortAssistant Change port permission:

sudo chmod 666 /dev/ttyUSB0

Some Thoughts

Memory usage is different from that of a general microcontroller like Stm32.