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19 November, 2010

ReflashBlinkM: Update your BlinkM’s firmware

All BlinkM-family devices can have their firmware updated. This makes them great for tiny development boards for ATtiny processors. ReflashBlinkM is an application that makes it easy to put back the original firmware or update a BlinkM to the latest firmware.

Previously you needed an AVR ISP programmer like the AVRISPmkII or the USBtinyISP. Thanks to the ArduinoISP sketch that ships with Arduino, if you have already have an Arduino, you can easily reflash your BlinkM with new firmware.

The ReflashBlinkM application is a tool for Mac OS X and Windows that uses ArduinoISP to help you reflash BlinkMs to their default firmware.

This is what it looks like:

Here’s one way of hooking up a BlinkM to an ArduinoISP:

And here’s a video of a BlinkM MinM being reflashed:

For full instructions, see the ReflashBlinkM page in the blinkm-projects Google code site.

25 September, 201027 September, 2017

SoftI2CMaster: Add I2C to any Arduino pins

[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
i2c.write('c');
i2c.write(255);
i2c.write(0);
i2c.write(200);
i2c.endTransmission();

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 );
  Serial.println("BlinkMSoftI2CDemo");

  BlinkM_off(0);

  for( int i=0; i< 100; i++ ) {  // flash the blinkms
    BlinkM_setRGB( blinkm_addr, 255,255,255 );
    delay(10);
    BlinkM_setRGB( blinkm_addr, 0,0,0 );
    delay(10);
  }
}

void loop()
{
  byte r = random(255);
  byte g = random(255);
  byte b = random(255);
  
  BlinkM_setRGB( blinkm_addr, r,g,b );
  delay(10);
  BlinkM_fadeToRGB( blinkm_addr, 0,0,0 );
  delay(1000);
}

void BlinkM_off(byte addr)
{
  BlinkM_stopScript( addr );
  BlinkM_setFadeSpeed(addr,20);
  BlinkM_setRGB(addr, 0,0,0 );
}

22 September, 201022 September, 2010

Hacking USB HID for Easy Tethered Ubicomp

At this years Sketching in Hardware conference, I gave a talk on the general approach I used to create LinkM, ThingM’s USB-to-I2C adapter for programming and controlling BlinkMs. I called it “Hacking USB HID for Easy Tethered Ubicomp” (4.8MB PDF) to give it a form that fit within some of the larger issues I’ve been dealing with in creating easily usable ubiquitous computing devices.

USB has many different (and confusing) aspects to it. I’ve long advocated the creation of a set of libraries and patterns to make “driverless” USB a reality. A sort of training wheels for USB. At the time I called this USB on Rails”, poking fun at RoR.

To me the key to this ease-of-use was the HID class in USB. No driver is needed when plugging in something like a mouse or keyboard. Other built-in device class drivers include CDC (modems), Mass storage, audio (headset), and video (webcam).

While researching HID, trying to make LinkM a “USB on Rails” project, I found that the biggest hurdle was a consistent host-side USB API that would let one write one set of code that could easily be ported to Mac OS X, Windows, and Linux. Libusb works well enough for Unix-like OSes like Linux and Mac OS X, but the Windows variant libusb-win32 required a driver install. So I put HID away.

For many months I investigated using CDC instead of HID because it maps down to a serial port on modern operating systems. Unfortunately, CDC has two main problems. For the “serial port emulation” mode, mapping to serial port semantics is problematic for a USB device that can be removed at will. If a device is removed while it is still “connected”, the OS and application can get confused or crash. Also, the CDC driver implementation seems brittle on Mac OS X. Some CDC devices can work fine, others wouldn’t. I can see now why FTDI and similar vendors use a custom driver for their USB-to-serial chips.

When looking back into HID after the frustration with CDC, I discovered that V-USB, the software-only USB firmware stack for AVR microcontrollers, had two interesting HID-based projects in them with a cross-platform host-side library for talking HID. The first was BootloadHID, a HID-based bootloader, and the second was “hid-data”, one of the examples. And there was a nice discussion of the platform differences on the V-USB wiki.

With that, I took both of those projects, generalized them slightly, then specialized them for LinkM and made them the core of the LinkM project. You can view the resulting source at the LinkM Googlecode project.

30 May, 2010

ThingM at Maker Faire 2010

My company ThingM had an official presence at Maker Faire this year. We were showing off the BlinkM line, including the new BlinkM MinM and the LinkM USB BlinkM controller. It was a lot of fun. And packed!

(click any photo to go to larger version on Flickr)

We were in the Maker Shed building, right underneath the Arduino banner, so we got lots of awesome questions about Arduino. The most common: “So I just picked up this thing that says ‘works with Arduino’…well, what *is* Arduino?” It was so great to see so many people interested in building their own gizmos.

By far the most fun demo we had was TwitM, the Twitter-controlled BlinkM. Using LinkM, a couple BlinkMs, and a Processing sketch, I had it so anyone who tweeted anything with the keyword “makerfaire” made one BlinkM flash. If you tweeted “blinkm colorname”, where colorname was any color in the X11 color names or a hex color code RRGGBB, the other BlinkM would turn that color. Because of the streaming Twitter API, these changes happened instantly; it was really something to see.

Kim and Mike made up some really nice “walltext” describing the various demos we had up.

A big hit was MaxM controlling RGB LED flexible circuit tape, using the same techniques I used for the Crystal Monster.

This was about regular busy at the Faire. There were many times when it got way more packed.

22 March, 201022 March, 2010

MobileMe Free: iPhone to iCal OTA syncing

I’ve been frustrated with my calendars not being in sync between my iPhone and my Mac’s iCal. I’ve inadvertently double-booked myself many times. I didn’t want to spend $99 a year for MobileMe because I already spent a lot on remote servers and don’t need most of what MobileMe offers. I just want calendar syncing. The below has been described by many others, in much greater detail and clarity. This is really a list of things I did so I can remember it.

The essential idea is both iCal and the iPhone Calendar program can talk to a CalDAV server, much like Mail.app and iPhone Mail can talk to an IMAP server. Google Calendar is a CalDAV server, so let’s use that, since it’s free and already set up. If you already have a CalDAV server, you can use that instead as the intermediary.

1. Create calendars in Google Calendar

Sign into Google Calendar and set up however many calendars you want. Once you do that, go to the bottom of the settings details for a particular calendar you’re interested in and note its “calendar address”:

2. Set up iCal to sync with Google Calendar

In Preferences in iCal, go to Accounts, click the “+” to add an account, and choose “Google” as the account type. Fill in your info.

Click on the “Delegation” tab for the newly created account, and pick which other calendars you want besides your main one (if any). You’ll see them in a separate list in the calendar list pane.

Now you have calendars that sync between iCal and Google Calendar.

3. Set up iPhone to sync with Google Calendar

On the iPhone Settings app, go to the “Mail, Contacts, Calendars” section and scroll down to “Add An Account…”. Choose “Add CalDAV Account” and fill in your Google Calendar login info.

If you just have the one main calendar on Google Calendar, that was the last step, you’re done and any changes you make on the iPhone will get send to your Google Calendar, which iCal will then pick up. And vice-versa. If you want to add one of the secondary calendars, you have one more step.

4. Adding a “delegate” Google calendar to iPhone

To add secondary Google calendars (what iCal calls “Delegates”), you need to do step (3) again. Then with this second CalDAV account on the iPhone, go into its “Advanced Settings” section of that account’s information and edit the Account URL. Replace the “username@gmail.com” part of the URL with the Calendar address you noted down from step (1).

That is, the full CalDAV URL for my main Google calendar is:
https://www.google.com/calendar/dav/tod.kurrt@gmail.com/user
and the full CalDAV URL for my “things-to-do” calendar is:
https://www.google.com/calendar/dav/c96o9s8ne6fb070cle0frp8e58@group.calendar.google.com/user

You’ll probably find it easier if you email yourself this URL from your computer, pull it up on your phone, and use copy-n-paste to enter it.

7 March, 20108 March, 2010

BristleBots and LED throwie art at Crash Space!

This upcoming Tuesday, 9 March 2010, 8pm at Crash Space in Culver City, we’ll be having some fun quick DIY projects for you to build. Come on over and have fun with us. The project kits are $5 for CrashSpace members or $10 for non-members and you can take them home after you build them.

In the kit you get the parts to build your own Bristlebot, a tiny robot made from a toothbrush:

(consists of toothbrush, pager motor, battery, and foam tape)

and LED throwie art:

(consists of two color-changing RGB LEDs, battery, and a magnet)

We’ll have a Bristlebot race track you can do time trials on:

And we’ll be showing you how to build all of this, no previous experience required. Come build bots and lights!

2 January, 201018 February, 2010

Momentary Button as On/Off Toggle using 555

(as a few had noticed, I had an error in the schematic shown. It’s been updated, thanks!)

A recent question from a friend who made a really cool BlinkM hoodie was: How can you turn a momentary button press into an on/off toggle?

There are tons of ways to do this if you like getting into electronics. Most all work off of some flip-flop like principle. And while I could have suggested a true flip-flop chip, I thought it would be cooler if you could use a 555 timer chip (which contains a single flip-flop and a couple of comparators). After scouring my childhood collection of Forrest Mims electronics books and a few 555 timer devoted websites (two of the best I found were: http://www.bowdenshobbycircuits.info/ & http://www.kpsec.freeuk.com/555timer.htm), I cobbled together the following circuit based off a few almost-what-I-wanted examples.

This is what it looks like in use:

The schematic is pretty straightforward, but does use a bit of feedback trickery to get the toggle functionality:

(old incorrect version here)

The parts cost is pretty low. The 555 timer chip can be had for about $0.43, the 2N3904 transistor for ~$0.40, and various resistors & capacitors are essentially free if you have them.

The circuit has 3 external two-pin connections: 5V&Gnd, button input, and the two pins of the thing to switch. In this case, the switched thing is a power supply to a BlinkM.

By changing the transistor to a beefier one, you can switch much larger loads. The little 2N3904 transistor in there now can switch around 200mA, but a bigger NPN or FET transistor and you could switch a few amps.

It can be made pretty small on a tiny breadboard (courtesy of FunGizmos.com) like this:

It’s not the greatest for battery-powered applications. When “off” it draws about 4-6mA, depending on the brand of 555 timer chip you use. When on it draws that plus whatever power the switched device draws. Best to put a proper power switch on the battery pack to eliminate this quiescent drain.