Search Results : Arduino

Jan 232017

Currently I’m the main maintainer of node-hid, the Node.js package that lets you talk to USB HID devices like blink(1).  I recently cribbed automated build config from node-serialport so now node-hid is automatically built for Mac, Linux, & Windows and Node 4.x,6.x,7.x.   It’s pretty cool to have these robots doing my bidding.  But did you know you can do automated builds of Arduino sketches too?  I didn’t until last night and it’s AMAZING.

For instance, that CrashSpace BigButton Arduino sketch I mentioned previously, is now getting automatically recompiled for the Wemos D1 mini ESP8266 board every time I check in. See?

How is this magic done?

Continue reading »

 Posted by at 3:56 pm
Dec 102013

[originally posted on the ThingM blog]

The theme for the Caltech Entrepreneurs Forum’s November event was “The Internet of Things, Arduinos and the ‘Maker Entrepreneur’“.


My talk “Intro to the Arduino Entrepreneurial System” touched on all these topics. The entire event was a blast, including a wonderful talk about commercial making with open source by Quinn of QtechKnow.

Slides with notes and MP3 audio of the entire event are below.

Download MP3 of the entire Forum proceedings, including Tod’s talk.

 Posted by at 1:39 pm
May 112013

I finally got around to updating the BlinkMuino guide for turning your BlinkM, BlinkM MinM, or BlinkM MaxM into a tiny ATtiny85 or ATtiny84 Arduino system. BlinkM boards make great tiny development boards, especially if you’re interested in driving LEDs. BlinkM MaxMs are particularly great because they have more inputs and those three beefy MOSFET power transistors. And MinMs are good because they’re super tiny, but still contain a fully-programmable computer.

Thankfully, the ArduinoISP sketch has also been updated for Arduino-1.0, meaning you can use your Arduino as an AVR-ISP programmer, like this:


Here’s the original video I made about BlinkMuino:

We’ll be showing off some examples of BlinkMs programmed with Arduino at Maker Faire, some say “hi”!

 Posted by at 12:37 pm
Apr 292013

In late 2006 I wrote “arduino-serial“, mostly for myself, to help with stuff I was working on at the time. It was a very simple & small, cross-platform tool written in basic C for reading/writing serial ports.

Now nearly seven years later I still get regular questions and frustrations about it. Part of this is due to how Arduinos have changed over time. You used to have to hand-reset an Arduino board, now the act of opening the serial port resets it. This has its plusses and minuses, but it really made my original use-case of arduino-serial fail. Then there were just all the minor deficiencies of the program.

To address some of these issues, but still keep things small & light, I’ve done a bit of fix-up of arduino-serial. It’s now hosted on Github at:

Changes & Improvements

Some changes that I recently made to arduino-serial:

  • Separation of the application (arduino-serial.c) from the library (arduino-serial-lib.{c,h})
  • Fixed probable --read bug
  • Fixed --port open to allow re-opens
  • Added --sendline command to send a string followed by a newline
  • Added --flush command to clear out receive buffer
  • Added --eolchar option to let you specify your own end-of-line character if ‘\n’ isn’t appropriate
  • Added --timeout option to specify a read timeout (reads no longer block infinitely)
  • Added --quiet flag to make output more terse/machine-readable

Here’s what the new usage help screen looks like:

laptop% ./arduino-serial
Usage: arduino-serial -b <bps> -p <serialport> [OPTIONS]

  -h, --help                 Print this help message
  -b, --baud=baudrate        Baudrate (bps) of Arduino (default 9600)
  -p, --port=serialport      Serial port Arduino is connected to
  -s, --send=string          Send string to Arduino
  -S, --sendline=string      Send string with newline to Arduino
  -r, --receive              Receive string from Arduino & print it out
  -n  --num=num              Send a number as a single byte
  -F  --flush                Flush serial port buffers for fresh reading
  -d  --delay=millis         Delay for specified milliseconds
  -e  --eolchar=char         Specify EOL char for reads (default '\n')
  -t  --timeout=millis       Timeout for reads in millisecs (default 5000)
  -q  --quiet                Don't print out as much info

Note: Order is important. Set '-b' baudrate before opening port'-p'.
      Used to make series of actions: '-d 2000 -s hello -d 100 -r'
      means 'wait 2secs, send 'hello', wait 100msec, get reply'

Using arduino-serial

arduino-serial has always been designed so you can “pipeline” commands/options, but it wasn’t implemented very consistently. It’s a bit better now. You can do multiple send/read pairs, even use multiple serial ports, all from a single command-line invocation.

For example, if you have the “SerialCallResponseASCII” sketch from the Communications examples loaded onto your Arduino, you can run commands to take multiple data readings. In the example below, the order of operations are:

  1. serial port is opened (at 9600)
  2. the string “A” is sent (a single-byte)
  3. the first line is read
  4. sleep for 1000 milliseconds
  5. send “A” again
  6. read second data line
  7. flush read buffer (just to show we can)
  8. send “A” a third time
  9. and take a final reading
laptop% ./arduino-serial -b 9600 -p /dev/tty.usbmodemfd131 \
            -s "A" -r  -d 1000  -s "A" -r  -F  -s "A" -r
send string:A
read string:465,396,0

sleep 1000 millisecs
send string:A
read string:358,352,0

flushing receive buffer
send string:A
read string:307,305,0

The flush was put in there to demonstrate that you could flush the receive buffer mid-command if you wanted. It’s not required, but might help some situations.

To use multiple serial ports, you can do something like the below, which opens up one serial port at 9600 bps, does a send & receive, then opens another at 57600 bps and does a send & receive on it:

laptop% ./arduino-serial -b 9600 -p /dev/tty.usbmodemfd131 \
        -s "A" -r \
        -b 57600 -p /dev/tty.usbserial-A800f8ib \
        -s "hello" -r 
 Posted by at 5:43 pm
Dec 162010

I love Arduino but its lack of wireless bugs me. And it sucks that WiFi Shields for the Arduino cost as much a cell phone. I want something cheap. Turns out, small, cheap WiFi routers like the Asus WL-520gu can run the DD-WRT Linux firmware and act as serial-to-network gateway for Arduinos (or most any other USB device). Here’s how to do it.

(Hey, is this a Wifi-controlled BlinkM? I think it is.)

A quick video showing a router acting as a serial-to-network gateway:

This is not that new of a concept, hacking Linux onto a router for some neat DIY purpose. One of my favorite past hacks is MightyOhm’s WiFi Radio project. And of course, see my own book Hacking Roomba for an example of how to put a Roomba on the Net.

This post is specifically about trying to make a DD-WRT router a transparent gateway for an Arduino.

The steps are:

  1. Install DD-WRT Firmware
  2. Configure Router to be WiFi Client
  3. Do Some Tests
  4. Install USB Serial Drivers
  5. Install Serial-to-Network Proxy

Continue reading »

 Posted by at 2:48 am
Sep 252010

[update 20150128: changed links to SoftI2CMaster project on Github]

Ever wanted to use any pair of pins for I2C on Arduino, not just the dedicated pins on Analog 4 & 5? Me too, so I made a quick little Arduino library called “SoftI2CMaster”, available in the “blinkm-projects” Googlecode repository.

Get it here: SoftI2CMaster on github

It’s still a work in progress, but it can write data pretty successfully and do it over longer cables than normal.

For the VIMBY/Scion Hackerspace Challenge, I created an array of BlinkM MaxM-powered accent lights for the device we made. Because the I2C cable was longer than a few feet, the normal Wire library that BlinkM_funcs.h uses to communicate with BlinkMs couldn’t be used. This is because the Wire library assumes a perfect bus. If there is any noise or other bus problems, the Wire library will currently lock up. For the SoftI2CMaster library, I wanted it to be very tolerant, even lazy, about bus problems and also have more tunable timing to let you slow the bus down. Of course, you still need pull-up resistors on the two lines. I’ve found using 2.2k resistors to be good.

The SoftI2CMaster API follows Wire’s API pretty closely:

  • SoftI2CMaster(sdaPin,sclPin) — create an new SoftI2CMaster for the two pins specified
  • beginTransmission(address) — begin sending data
  • write(data) — send some data (byte or byte arrays)
  • endTransmission() — stop sending data

In use it looks something like this:

#include "SoftI2CMaster.h"
const byte sdaPin = 7;
const byte sclPin = 6;
SoftI2CMaster i2c = SoftI2CMaster( sdaPin,sclPin );

i2c.beginTransmission( 9 );  // write to address 9

There is a simple demo for BlinkMs that this library currently lives in. It’s called “BlinkMSoftI2CDemo” and shows off a simplified BlinkM_funcs called “BlinkM_funcs_soft.h“. The entirely of BlinkMSoftI2CDemo is shown below.

const byte sdaPin = 7;  // digital pin 7 wired to 'd' on BlinkM
const byte sclPin = 6;  // digital pin 6 wired to 'c' on BlinkM

#include "SoftI2CMaster.h"
SoftI2CMaster i2c = SoftI2CMaster( sdaPin,sclPin );

// must define "i2c" before including BlinkM_funcs_soft.h
#include "BlinkM_funcs_soft.h"

byte blinkm_addr = 9;

void setup()
  Serial.begin( 19200 );


  for( int i=0; i< 100; i++ ) {  // flash the blinkms
    BlinkM_setRGB( blinkm_addr, 255,255,255 );
    BlinkM_setRGB( blinkm_addr, 0,0,0 );

void loop()
  byte r = random(255);
  byte g = random(255);
  byte b = random(255);
  BlinkM_setRGB( blinkm_addr, r,g,b );
  BlinkM_fadeToRGB( blinkm_addr, 0,0,0 );

void BlinkM_off(byte addr)
  BlinkM_stopScript( addr );
  BlinkM_setRGB(addr, 0,0,0 );
 Posted by at 12:14 am