Jetson/Tutorials/Program An Arduino

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Revision as of 18:25, 23 September 2014 by Shervin.emami (talk | contribs) (Made it clear in the intro that this describes programming the Arduino, not communicating with it.)
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Introduction

Arduino devices are very simple-to-use microcontroller boards commonly encountered in embedded projects, and can communicate with a Jetson TK1 via Serial UART or I2C, or can be programmed from a Jetson TK1 through USB (ie: allowing you to develop Arduino code using a Jetson TK1 instead of using a PC for development). This tutorial describes how to program an Arduino board from a Jetson TK1 (instead of from a PC). This tutorial does not describe how a Arduino can communicate with a Jetson TK1.

FTDI kernel module

Upon connecting an Arduino's USB port to the Jetson, we can see the Arduino uses an FTDI serial-to-USB converter:

ubuntu@tegra-ubuntu:~$ lsusb
Bus 002 Device 006: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC

However support for the FTDI converter device is not set in the kernel configuration by default:

ubuntu@tegra-ubuntu:~$ zcat /proc/config.gz | grep FTDI
# CONFIG_USB_SERIAL_FTDI_SIO is not set
# CONFIG_USB_FTDI_ELAN is not set

We will need to compile the FTDI kernel module from source to use the device.

L4T kernel source

First, download the kernel sources (kernel_src.tar.bz2) from https://developer.nvidia.com/linux-tegra-rel-19 and copy the archive to the Jetson, into the ubuntu user home directory. Then extract the tarball to ~/kernel:

tar xvjf kernel_src.tar.bz2

Configuring the kernel

Copy over the Jetson's existing kernel configuration to the newly-extracted kernel source:

zcat /proc/config.gz > ~/kernel/.config

Next build & launch the menuconfig tool to configure the kernel options. menuconfig requires ncurses to be installed, hence the apt-get command first.

sudo apt-get install ncurses-bin libncurses5-dev
make menuconfig

Navigate to Device Drivers -> USB Support -> USB Serial Converter Support

Choose 'M'odule for USB FTDI Single Port Serial Driver

Save changes and exit.

Verify that the FTDI component is now set to build as module:

ubuntu@tegra-ubuntu:~/kernel$ cat .config | grep FTDI
CONFIG_USB_SERIAL_FTDI_SIO=m
# CONFIG_USB_FTDI_ELAN is not set

Building modules

make prepare
make modules_prepare

make M=drivers/usb/serial/
  Building modules, stage 2.
  MODPOST 2 modules
  CC      drivers/usb/serial/baseband_usb_chr.mod.o
  LD [M]  drivers/usb/serial/baseband_usb_chr.ko
  CC      drivers/usb/serial/ftdi_sio.mod.o
  LD [M]  drivers/usb/serial/ftdi_sio.ko

Installing the FTDI module

sudo cp drivers/usb/serial/ftdi_sio.ko /lib/modules/$(uname -r)/kernel
sudo depmod -a

Verify installation

Now when the Arduino is plugged in, we see the FTDI module loaded and /dev node assigned:

ubuntu@tegra-ubuntu:~/kernel$ dmesg | grep usb
[   57.385970] usb 2-1.5: new full-speed USB device number 5 using tegra-ehci
[   57.407931] usb 2-1.5: New USB device found, idVendor=0403, idProduct=6001
[   57.407950] usb 2-1.5: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[   57.407964] usb 2-1.5: Product: FT232R USB UART
[   57.407976] usb 2-1.5: Manufacturer: FTDI
[   57.407987] usb 2-1.5: SerialNumber: A601NG2B
[   57.479238] ftdi_sio: version magic '3.10.24 SMP preempt mod_unload ARMv7 p2v8 ' should be '3.10.24-gf455cd4 SMP preempt mod_unload ARMv7 p2v8 '
[   57.504885] usbcore: registered new interface driver ftdi_sio
[   57.507384] usbserial: USB Serial support registered for FTDI USB Serial Device
[   57.508073] ftdi_sio 2-1.5:1.0: FTDI USB Serial Device converter detected
[   57.508917] usb 2-1.5: Detected FT232RL
[   57.508934] usb 2-1.5: Number of endpoints 2
[   57.508948] usb 2-1.5: Endpoint 1 MaxPacketSize 64
[   57.508960] usb 2-1.5: Endpoint 2 MaxPacketSize 64
[   57.508971] usb 2-1.5: Setting MaxPacketSize 64
[   57.511143] usb 2-1.5: FTDI USB Serial Device converter now attached to ttyUSB0

In this case, the port has been assigned to /dev/ttyUSB0. Remember this for when using the Arduino IDE.

Using the Arduino IDE

Running the Arduino IDE on the Jetson is easy, as it's included in the Ubuntu 14.04 repository, and allows one to use the Jetson to develop & upload sketches directly to the Arduino board.

sudo apt-get install arduino arduino-core

Jetson arduino ide.jpg

Arduino Duemilanove ATmega328 running Blink example while connected to Jetson TK1 board over USB

Testing with Blink example

Test the Jetson's ability to connect & upload sketches to the Arduino by running the Blink example. At this point, the directions for using the Arduino are the same as from any other platform (like Windows/MacOS), as can be followed at http://arduino.cc/en/Guide/Windows#toc6


Serial communication

User applications that need flexible communication between the Jetson & Arduino can implement it using RS232 serial.

On the Arduino side, communication is implemented with the Serial API.

On the Jetson side, the user would open() /dev/ttyUSB0 and perform read/write calls on the returned descriptor, using termios.h for configuring options like baud rate, ect.

TODO example serial code