PPTX - Intel Software Academic Program

Intel Do-It-Yourself Challenge
Lab 6: USB and servo motors
Nicolas Vailliet
[email protected]
Intel Software
Prerequisites and objectives
We assume that:
- You are able to download an archive, to unzipped it and run a
program under the OS you’re familiar to.
- You are able to read pieces of code and comments written in C-like
Our objective is:
- Given a Galileo board and a laptop connected on the same network,
a Pololu Micro Maestro 6 USB Servo controller, and a servo motor,
you will be able to control the motor from Galileo. You will use C++
In general,
Our goal is to show you more Galileo possibilities and to develop your
imagination on IoT world.
Before you start
What do you need?
Desktop OS
We assume you’re under Microsoft Windows.
Linux and Mac users should not have any problem to do the same.
An Intel Galileo Development Board.
The box comes with power supply and cable.
A Wi-Fi adaptor (N-2200 Mini-PCIe)
A micro SD card (8GB with the full Linux image we provide)
A Pololu Micro Maestro 6 USB controller
- A USB cable Type A – Type B
- A servo motor
- A USB cable to power up the motor
A SSH client like Putty for Windows. Mac and Linux users only need a terminal.
Binaries we provide: « set_acceleration », « set_target », « set_speed »
Controlling servo motors
Preparing hardware
Read before doing anything!
It could damaged Galileo and laptop!
Connecting hardware
- Plug and boot your board.
- Connect the Pololu card to Galileo on
USB host connector.
- Connect a servo motor on Pololu.
- Connect the USB power wire to Pololu
- And plug it to your laptop.
- See next slide to know how to connect
the USB power wire to the Pololu.
- Connect the servo signal connector
(yellow-ish wire) to the pin closest to the
USB port of the Pololu card.
Preparing hardware
How to connect the hardware?
Bash script to control a servo motor
We provide you three binaries to control:
- The targeted position of the servo motor
- The speed of the servo motor (0 is max speed)
- The acceleration of the servo motor (0 is max acceleration)
How to run this files
# ./set_target channel value
# ./set_accel
# ./set_speed 0
# ./set_target 0
The order is automatically sent to the Pololu card via USB.
These binaries are C++ program using libusb-1.0.
Bash script to control a servo motor
A simple bash script to control a servo motor
#! /bin/bash
while : # infinite loop
./set_target 0 4000
# channel 0 targeted position is set
to 4000
sleep 1s
# we wait a second
./set_target 0 8000
sleep 1s
You can now use these three binaries to write your
own script/program to control servo motors!
Optionally: look at the C++ source code on next slides!
Set_target source code
A C++ main function using libusb
#include <iostream>
#include <string>
#include <libusb-1.0/libusb.h>
#include <unistd.h>
#include <stdlib.h>
using namespace std;
int main(int argc, char *argv[]){
if(argc < 3)
cout << "Usage: binary servo_number target_value" << endl;
int servo = atoi(argv[1]);
int value = atoi(argv[2]);
Set_target source code
Creating libusb structures
libusb_device **devs;
libusb_context *ctx = NULL;
libusb_device_descriptor descr;
libusb_device *pololu;
string idPololu ("137");
int r;
int found = 0;
ssize_t cnt, i;
Initializing libusb
r = libusb_init(&ctx);
libusb_set_debug(ctx, 3);
Seeking devices
cnt = libusb_get_device_list(ctx, &devs);
Set_target source code
For each device found
for(i = 0; i < cnt; i++) {
r = libusb_get_device_descriptor(devs[i],&descr);
//pololu id is 137, so let’s find it
if(descr.idProduct == 137)
pololu = (devs[i]);
found = 1;
Stop looking for devices and don’t unreference the pololu
Set_target source code
Sending target command
if(found) {
libusb_device_handle **handle;
r = libusb_open(pololu,handle);
r = libusb_detach_kernel_driver(*handle,0);
if(r < 0 && r != LIBUSB_ERROR_NOT_FOUND) {
cout<<"Error: detach kernel driver
return 1;
r = libusb_claim_interface(*handle,0);
r = libusb_control_transfer( *handle,0x40,//request type
value, //value
servo, //servo number
Set_target source code
Closing USB connection
r = libusb_release_interface(*handle,0);
libusb_free_device_list(devs, 1);
return 0;
What’s next?
Optionally, integrating Galileo with Android?
An IoT project which need a remote? Use your Android
smartphone to control Galileo!
After that, your mission will be…
…to implement your own idea!
…to realize the project we suggest!
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