MixiClock - 4 digits displayed on 8x8 LED matrix

So far, on a 8x8 LED matrix, I have only seen the time displayed with scrolling numbers (beside the geeky binary/hex/tix/dice/dots/bars or other coded formats). There is simply not enough room to statically display 4 digits at once, since the tiniest set of human-readable digits can be defined in a grid not smaller than 3x5 pixels.

I challenged myself to find an intuitive way to display 4 digits on the "standard" 8x8 matrix. I figured that this is possible if using 2 colors. Even though they may overlap a bit (quite literally), digits of different colors can be easily distinguished. This is because the overlap makes a third color: in the case of the bi-color (red/green) LED matrix, it will be orange.

I focused on two aspects:

• font definition (3x5) as simple as possible, with minimal number of "on" pixels, but still readable;

// tiny 3x5 digits;

byte digit[10][5] = {

  {2, 5, 5, 5, 2},  // 0

  {1, 1, 1, 1, 1},  // 1

  {6, 1, 2, 4, 7},  // 2

  {7, 1, 2, 1, 6},  // 3

  {4, 5, 7, 1, 1},  // 4

  {7, 4, 7, 1, 6},  // 5

  {3, 4, 7, 5, 2},  // 6

  {7, 1, 2, 4, 4},  // 7

  {7, 5, 2, 5, 7},  // 8

  {2, 5, 7, 1, 6},  // 9

};

• optimal placement of the digits on the 8x8 matrix, so the overlap is minimal (sometimes 1 pixel, very rarely 2 pixels). The photo below shows the starting point. There is more tweaking of the positions in the code, depending on the combination of digits.

As for the name, there are not too many choices, most of them are already taken, so I hastily settled for "MixiClock" (I am open to suggestions though :).

The sketch, written for my 8x8 bi-color LED matrix shield (also used in the original glass-domed Wise Clock) can be downloaded from here. It should be easy to adapt it to any other RG 8x8 LED matrix. The code also features setting up the clock using two buttons.

As you may have guessed, the top digits (green) indicate the hours, the bottom ones (red) the minutes. The position of the digits changes slightly depending on the combinations, so that there is no overlap or it is minimal (max 2 pixels, and those will be orange). The code is not final and I am sure it can be improved.

As always, comments and suggestions are welcome.

Adventures in WiFly land - Part 1

This was a bit of a struggle, working with the XBee-footprinted WiFly RN-XV module from Roving Networks.

The goal was to get some data from the RSS feeds, kind of what this project had achieved.

First, I tried to set up the RN-XV module following this crash course (and using ladyada's XBee adapter with the FTDI cable). Everything went fine except connecting to my home WiFi network: I kept getting "AUTH-ERR". Eventually, after many tries, the module joined the network. I thought this is caused by the weak WiFi signal and other people may experience a similar scenario (which should be dealt with by the software).
Then I found with this software library, which, of course, did not work in my special case. After I started tweaking it and read the RN-XV manual once again, I found the explanation: WPA (which I am currently using) handshaking takes more than 1,000ms (1 second), which is the default timeout for the module. The solution was to increase this timeout (to 5000ms) with the command

set opt jointmr 5000

I ended up writing this sketch that makes requests to Yahoo's weather and stock quotes RSS feeds. It should work with the mentioned WiFly library (if they don't keep changing it).

Actually, I had to modify the library a bit too, to include my own specific commands in the initialization procedure. So I created this new function

boolean WiFlyDevice::myInit()

{

  if (!enterCommandMode())

  {

    DEBUG_LOG (1, "Failed to enter command mode");

    return false;

  }

  // turn off remote string;

  sendCommand("set com remote 0", false, "AOK");

  return sendCommand("set opt jointmr 5000", false, "AOK");

}

then modified begin() to look like this:

void WiFlyDevice::begin() 

{

  DEBUG_LOG(1, "Entered WiFlyDevice::begin()");

  if (!bDifferentUart) SPIuart.begin();

  myInit();

}

Another detail worth mentioning is the tuning of the delay between sending the request and reading the response. If this delay is too long, the response buffer gets overwritten, so response data is lost. If the delay is too short, the response is not there yet. Similar consideration while retrieving the response data from the buffer: we need to wait a bit for more data to come before we can say (kind-of) for sure that all data was received.

Next step (Part 2) is to parse the responses to find the correct values we are looking for, temperature and stock price, respectively, then to display them on Wise Clock 4.

Note: The RSS feeds I used are 

http://weather.yahooapis.com/forecastrss?w=24153215&u=c

and

http://pipes.yahoo.com/pipes/pipe.run?_id=ZKJobpaj3BGZOew9G8evXg&_render=rss&ticker=INTC

They could be custom-replaced with any other URL that returns a small(ish) set of XML data for easy parsing.

ZeeClock - nice mod running on Wise Clock 4

Here we have the first "independent" mod running on Wise Clock 4, thanks to Mr. Jon S!



Jon shared the code (download it from here) and added this description:

This is an alarm clock for my toddler who can't tell time (of course). It uses colors to tell him when he should be sleeping and when he should get up.
I didn't need to, but I wrote all the code so it's self contained including setting multiple alarms, setting the time, and turning the audio on and off.
It's not perfect (I'm an artist not a programmer so the code is a bit of a mess), but it does the job.

I think it's a great job!
Thanks again Jon.

Wise Clock 4 - time synchronization with GPS

This is my first foray into the world of GPS, made possible by the GPS XBee kit.
With Wise Clock 4 offering support for XBee, this little GPS module from seeedstudio seemed like a nice fit. The purpose is, of course, to synchronize the clock with the accurate time received from satellites.

Note: Some time ago I tried the WWVB atomic clock radio receiver module CMMR-6. It comes with a 60mm ferrite rod, pretty inadequate for receiving the Colorado radio signal in Toronto, more than 2200km away. On top of the fact that it is finicky (never worked for me), it is also bulky (the ferrite rod) and fragile (the thin antenna wire).

First, I inserted the module into the XBee adapter from adafruit, which is connected (through the FTDI cable) to a terminal session (9600, 8, N, 1).

Messages started flowing in, right off the bat: wow!

Next, I moved the GPS module onto the Wise Clock 4 and uploaded a sketch that uses TinyGPS library (modified by Justin).

Here is the serial monitor output.

For those who require maximum accuracy on top of the one provided by the DS3231 RTC chip itself, this GPS solution should do it.

Homework
Make the "Doomsday clock", like the one by Wyolum team shown in the video below, with Wise Clock 4 and 2 displays.



Update: Homework done.

Old projects revisited

I recently had to revisit the (original, glass domed) WiseClock and the SillyClock.

On WiseClock I streamlined the software (download from here) to only show the time and quotes. It also allows the time to be set from buttons as opposed to the Sony TV remote control (the Reset button on the 8x8 LED matrix shield was re-purposed/re-routed). As well, the character set is now defined in progmem as opposed to internal microcontroller EEPROM (font1.h contains the font definition).
The method I chose for setting the time is to show the hours in red and the minutes in green, and alternate between hours and minutes by pressing the left button (now named "Set"). The left button (the former "Reset") is now named "Inc" and connected to A2/D16 (a pull-up 10k resistor is also required), as shown in the photo.

This button is used for incrementing the hours or minutes. Once the right time is set, the clock will revert to displaying the scrolling quotes and time.

On SillyClock, the software (download from here) can now handle the tilt switch (on the "Dual RG bi-color LED matrix shield") and also sound the alarm.
Two hardware hacks are required:

• addition of a pull-up 10k resistor on A0;
• addition of a piezo buzzer between A1 and ground.