Introducing the "6-character alphanumeric LED Arduino shield"

This shield offers a quick way to add alphanumeric display capabilities to your Arduino project. It is based on the 14-segment 6-character LED display driven by two multiplexed MAX7221 drivers, through a method described in this application note.

 US$ 26 - free shipping to North America

The kit includes:

• PCB
• 2 x MAX7221 + 2 x 24-pin sockets
• 6-character 14-segment common cathode LED display
• 2 x 33k resistor
• 2 x 100nF capacitor
• machined header (as socket for the display)
• male header (for the shield)

The board has a small prototyping area for adding project-specific parts, for example buttons and buzzer if you want to build an alarm clock (basic clock code for this shield here). Assembled, showing the time (from wsduino):

or, displaying text:

The shield uses Arduino pins D3, D4 and D5.

Introducing wsduino

This project is actually a revisit of my old Wiseduino, with the same goal: an Arduino-compatible with on-board Real Time Clock, and some extras (in this case, an XBee-like device, e.g. BTBee, GPSBee, WiFly). I renamed it "wsduino", although the pronunciation should remain the same :)

I redesigned wsduino mainly for the Axiris IV3 clock, whose enclosure allows for only 2 boards (Arduino + IV3 shield), with openings for power socket, USB, and no accessible buttons. Essentially, wsduino saves you an extra shield, which would have hosted the RTC (+backup battery) and the XBee.

 US$27 - free shipping to North America

wsduino is now available as a kit, as shown in the photo below.

The wsduino kit includes:

• PCB
• ATmega328 processor with bootloader
• 28-pin socket
• 16MHz crystal
• 2 x 22pF capacitor
• power jack
• 7805 voltage regulator
• 1N4001 diode
• USB miniB socket
• DS3231 RTC (SMD)
• A1117 3V3 regulator (SMD)
• CR1220 battery + holder
• 4 x 10k resistor
• 4k7 resistor
• 3 x 100nF capacitor
• 47uF/25V capacitor
• 47uF/16V capacitor
• 470uF/10V capacitor
• 2 x 10-pin 2mm female header for XBee
• 40-pin 0.1" female header
• 3-pin header + jumper (selection of power source)

An FTDI breakout is required to upload sketches.

Although the assembly is quite trivial, I enumerate below the steps, for the detail-oriented :)

1. solder the DS3231 SMD chip on the bottom of the PCB, making sure the chip orientation is correct;
2. solder the A1117 chip, also on the bottom of the PCB;
3. solder the resistors R1-R4 (their values are shown in silkscreen);
4. solder the IC socket, with the correct orientation of the notch; then insert the ATmega328 chip (after you bent the two sides of pins on a flat surface, one side at a time, to become parallel);
5. solder the crystal (orientation does not matter)
6. solder the USB miniB socket;
7. solder the 7805 voltage regulator to match its shape in silkscreen;
8. solder the ceramic capacitors (orientation does not matter);
9. solder the 3 electrolytic capacitors, paying attention to their orientation;
10. solder the diode, also paying attention to its orientation;
11. solder the power jack;
12. solder the 2 XBee headers;
13. cut, then solder, the extension headers;
14. solder the battery holder, then insert the battery.

Schematic and board layout are shown below.

Here are some photos of the assembled board.

A  minimal wsduino is shown below, with the ATmega328 running on the internal oscillator at 8MHz, powered directly through the USB miniB socket.

The RTC (DS3231) and 3V3 voltage regulator are soldered on the bottom.

Perfect Arduino-compatible to quickly build a clock. Just add a display shield :)

WiFiChron clock kit now available

Update Sep 18, 2017: Here is the latest revision of the PCB included in the kit.

Update Oct 8, 2015: The latest revision of the PCB (pictured here and here) has hardware support for XBee (which also covers GPSBee, WiFiBee and BTBee).

With this kit you build a clock like the ones shown in the photos below.

Last one, courtesy of Nick, features an yellow/amber display.

There are two buying options:

1. use or make your own enclosure

 (US$47, free shipping to North America)

2. enclosure included (Serpac A20, transparent front panel, screws, back panel hand-drilled with 3 holes for buttons and rectangular opening for the USB connector)

 (US$61, free shipping to North America)

The kit includes the following electronic parts:

• main PCB
• display adapter PCB
• ATmega328 with 8MHz bootloader, programmed with a clock sketch + 28-pin socket
• 74HC595 shift register + 16-pin socket
• HDSP-2534 8-character alphanumeric display + 4 x 6-pin machined headers
• DS3231 + battery holder + CR1220 coin battery
• LM1117 3V3 regulator
• 3 x right angle push button
• 5 x100nF capacitor
• 3 x 10k resistor
• 220uF (or so) electrolitic capacitor
• 2 x 12-pin right angle male header
• miniB USB connector
• buzzer

Schematic and board layout are shown below.

The board supports other types of displays as well, through the use of adapters. So far, beside the HDSP-2534 coming with the kit, there are adapters for HDSP-231x and QDSP-6064 (the sketch is different for this one), shown below.

Assembling the kit

Finding the right place for the components on the board should be straightforward, since the silkscreen shows their values and their orientation.

It is very important to pay attention to a few aspects:

• the orientation of the DS3231: the key (pin 1) must be the top-right on the board (so that you'll see the marking on the chip upside-down);
• solder the USB mini-B connector BEFORE the capacitors surrounding it, or otherwise you'll be forced to solder the USB's ground and Vcc pins (the 2 extreme pins among the 5) in a very cramped space;

The procedure to attach the display is as follows:

• first insert the little adapter PCB all the way into the right-angle headers, then the headers themselves into the main PCB; solder the headers to the main board first, making sure that the small PCB adapter is perpendicular on the main board;
• solder the display adapter PCB to the male headers, after it's inserted all the way, with the so the headers' pins stick out;
• cut the sticking pins to the PCB level; at this point you have the adapter attached and connected (perpendicular) to the board, and you are ready to solder the HDSP-2534 display;
• insert the machined headers into the HDSP-2534 display first, then insert the HDSP-2534 display with the attached machined pins into the adapter PCB until all pins are accessible on the other side;
• solder the machined pins, on the side facing the main board (the bottom row is just underneath the main PCB, the top row is above the main PCB). In the end, it should look like in the photo below.

Then insert the display with the key (the "cut" corner) in the left bottom of the adapter.

An assembly video can be also found in this post..

As of Oct. 8, 2015, an HCMS-29xx adapter is available (shared on oshpark), for use with the "serial"  intelligent displays (as opposed to the "parallel" HDSP-2534 coming in the kit).

ProMini clock shield with OLED display

Yet another ProMini clock shield kit, this time featuring a 128x64 I2C OLED display.

The kit can be purchased with or without the OLED display (I prefer you buy the OLED on your own, for example this excellent one from miker).

  US$30, includes OLED display, free shipping to North America

  US$16, OLED not included, free shipping to North America

The kit includes:

• PCB
• DS1307 SMD
• 32kHz crystal
• CR1220 coin battery
• battery holder
• optional: I2C 128x64 OLED display (blue or white)
• tactile switch (2x)
• resistor 10k (2x)
• machined male pins

The PCB was designed to accommodate I2C OLED displays with the 4-pin header configured either as VCC-GND-SDA-SCL or as VCC-GND-SCL-SDA.

The OLED clock can also be powered from the same LiPo battery shield for ProMini, as used in the bubble clock. To minimize current consumption (beside disabling the ProMini on-board LEDs), the processor can be awaken from sleep at the push of the "hours" button (on D3).

Schematic and board layout are shown below.

The OLED clock could show the time in many different ways, including Pong mode (sketch adapted from miker), analog clock mode, digital clock mode (sample sketches to be provided soon).

ProMini clock shield with 7-segment bubble display

Update May 6, 2016: This kit is no longer offered until I get a new batch of QDSP-6064 displays (whose price seem to have jumped considerably).

This clock was designed as a ProMini shield. It comes as a mostly-SMD kit, based on DS1307 with battery backup and the QDSP-6064 7-segment LED "bubble" display.

The kit includes the following:

• PCB
• QDSP-6064
• DS1307 SMD
• 32kHz crystal
• CR1220 coin battery
• battery holder
• 330 ohm resistor 0805 (8x)
• tactile switch SMD (2x)
• machined female pins

The assembled clock can be fitted with a LiPo battery shield for ProMini, as shown in this post (source code also provided there).
The current draw (measured at 20mA with an unmodified ProMini) can be minimized by removing the 2 LEDs on the ProMini board, as well as dimming the 7-segment bubble display through software (SevSeg library). One other way of maximizing the LiPo battery life cycle is by waking the clock from sleep mode at the press of the "minutes" button (on D2).

Schematic and board layout are shown below.

New kit in store: simple clock with HDSP-2534 display

Update July 31, 2020: See the latest revision here.

The centerpiece of this clock kit is the vintage-style 8-character display HDSP-2534 originally from HP, currently manufactured by Avago. The assembled clock looks like in the photo below. The dock, not included in the kit, is a miniB USB phone charger; it can be easily sourced from ebay, if you don't already have one. (You can even get a fancy one, e.g. custom-made exotic wood, on etsy.com.)

The kit includes the following components:

• PCB;
• ATmega328P, with bootloader and fuses for 8MHz internal clock, and the sketch preloaded (also downloadable from here);
• HDSP-2534 display;
• 595 shift register;
• DS1307 real time clock;
• 32kHz crystal
• CR1220 battery;
• battery holder;
• push buttons (x2);
• capacitor 100nF (x3);
• 10k resistor (x3);
• 28-pin socket;
• 16-pin socket;
• 8-pin socket;
• 6-pin machined female header (x4).

   $40, free shipping to North America

Note: The kit is currently out of stock. Please send me an email (my address is in the top right corner of the page) if you want one. I will put together only a small number of kits at this price, since the display itself is sold by digikey for about $40.

Schematic and board layout are shown below. Preliminary Eagle files can be found here.

The kit is super easy to assemble. It is really impossible to misplace components on the board.

Still, here is some advice:

• pay attention to the orientation of each of the three integrated circuits, when you insert them in their respective sockets;
• before soldering the battery holder, put some solder on the big center pad;
• avoid solder bridges between the USB miniB connector's terminals by wetting their pads (on the bottom side) with a flux pen;
• it is recommended, for aesthetic purpose, not to solder the FTDI connector to the board; if you need to upgrade the existing software (download from here), you can just hold the 6-pin make header tightly in place while uploading the sketch;

Black Friday (and beyond) sale

I was going to have a Black Friday sale anyway, but now I have one more reason for it, and it's an embarrassing one: the latest batch of PCBs have a little flaw, but they can be easily fixed. So, until I run out of them, both the Wise Clock 4 kit and the Complete Wise Clock 4 kit will be $10 less, for $57 and $115 respectively. (As always, I also offer discounts for multiple units, just ask.)

The photos below show a few ways to fix it. Basically, the GND terminal of the USB connector is disconnected from the board's ground. The short wire re-connects them again.

The sleekest way would be on the bottom, using a resistor terminal inserted together with the 2x8-pin female header, as shown in the photo below.

Solder the other end together with the 6-pin FTDI connector.

Here is the story of how this happened. The PCB used to be 101.2 mm in length. That was 1.2 mm longer than the 10 cm limit imposed when using Seeedstudio's PCB prototyping service. I never had a problem before, I always got them manufactured like they were 10 cm in length. Now, Seeedstudio decided to enforce the 10 cm limit (or pay up like they were in the next size bracket). I reacted by shrinking the board, cutting 1.2 mm from the right side. It seems that the 1.2 mm side was very important.

There is more, unfortunately: in the process of generating the Gerber files, I even forgot to select the "Top names" for the silkscreen, so now the resistors are not named at all.

When you install the resistors, keep in mind that 3 of them, with values of 4k7, must be positioned in the correct places, as shown in the assembling instructions. (The other resistors are all 10k, soldered stress-free in the remaining resistor places.)

And that's why the board is now essentially free with the kit. If you don't feel confident that you can do it, please ask me to fix it for you. I will solder the little bridge wire and also solder the three 4k7 resistors correctly. You do the rest.

Note: The photo shows the board bare, but the PCB in the kit comes with the SMD components (SD card socket, the DS3231 and the 3V3 regulator) soldered already.

And here is the (latest) schematic, for those interested in details.

Buy Complete Wise Clock 4 kit - includes display and enclosure

Update May 12, 2018
The complete kit is no longer offered since Sure Electronics discontinued the LED display.
I still sell the kit without the display, for those who can provide their own display, either from old stock or by making it themselves.
I may also have the bigger (5mm LED) display in stock, or may recycle some older ones. Please email me to inquire.


Update July 7, 2015
Before you buy, please read this post on assembling the Wise Clock 4 with the new display.


When you buy the "Complete Wise Clock 4 kit", on top of the Wise Clock 4 kit you get the 3216 bi-color (red/green/orange) LED display from Sure Electronics, plus the enclosure, consisting of two laser-cut transparent acrylic plates and the required hardware (standoffs, screws etc) to assemble it.

The "complete kit" comes with everything you need to build a functional Wise Clock 4. You will need to add your own FAT16/FAT32-formatted SD card (with the necessary files on it), the miniB USB power cable and, eventually, an BTBee module (if you want Wise Clock 4 to display messages sent from your Android device).

The assembly guide, written by StefanK, can be found here.

Buy Wise Clock 4 kit

The Wise Clock 4 kit includes the following parts (shown in the photo below):

• PCB;
• SD card socket (pre-soldered);
• DS3231 extremely accurate RTC (real time clock) chip, soldered to the board;
• MIC5219 voltage regulator, soldered to the board;
• 74HC125 level shifter (5V to 3V3), soldered to the board;
• 2 SMD LEDs (soldered);
• 3 SMD resistors (soldered);
• ATmega644P, with the latest Wise Clock 4 software;
• 40-pin socket; 
• 16MHz crystal;
• 2 x 22pF ceramic capacitors;
• CR1220 backup battery for RTC;
• holder for the coin battery;
• 3 x right-angle push buttons;
• 9 x 10k resistors;
• 3 x 4k7 resistors;
• piezo buzzer;
• USB miniB connector;
• 6-pin right-angle male header (FTDI connector);
• two 2x8-pin female headers (display connectors);
• two 10-pin 2mm female headers (XBee connectors);
• 220/470 uF electrolytic capacitor;
• 3 x 100nF decoupling capacitors.

Note that the first bunch of components in the list are SMDs and come soldered to the board (that is, I solder them for you).

US$67 US$57, free shipping to North America

Please contact me for pricing to outside North America. (Usually, for Europe, the price is $5 more.)

To build a finished Wise Clock 4, you need to add your own 3216 display (made by Sure Electronics and sold on their site or on ebay), which plugs directly into the board (no cables are required to connect the Wise Clock 4 board to the display). You will also need to build your own enclosure.

Please read this post on how to connect the Wise Clock 4 board to the redesigned version of the display.

Assembling the Wise Clock 4 kit is very similar to assembling Wise Clock 3, shown here. (The few differences between the two kits are related to the XBee, and are very easy to figure out. Regardless, all new components are SMD and they come pre-soldered.)

If you want the "Complete Wise Clock 4 kit", that includes the 3216 display and a simple yet elegant enclosure, please visit this page.

The ATmega644P processor comes already loaded with the latest software, so you don't need to use the Arduino IDE to compile and upload the code. Essentially, after soldering all components in place, Wise Clock  4 should work right away.

Upgrading the software on Wise Clock 4 (when a new release is published) is similar to Wise Clock 3, and this process is detailed here.

Also note that, although Wise Clock 4 has support for the XBee RF wireless modules, no XBee module is included in this kit.

Freebees

Purchase any of my kits and you can get one (or more, if you ask nicely :) freebee from this page (just email me with your choice).

I am currently giving away a few "surplus" boards and LED matrices.
Shown below are, from left to right:

• PCB for the LED matrix shield;
• PCB for Wiseduino rev. 1.7;
• PCB for the Dual bi-color LED matrix shield rev 1.4;
• PCB for the Dual bi-color LED matrix shield rev 2.0;

You can also get the PCB for DWex, a small Arduino + RTC, that you can make into a DIY pocket/pendant watch. This board is mostly SMD, but not difficult to solder with a little exercise.

Any of the above PCBs can be used as originally intended (for kits), since there is nothing wrong with them (as far as I know). The challenge in building the LED matrix shields is in finding the right matrices (which is almost impossible, since they were "kind-of" custom made for me by a Chinese LED company some time ago). Nevertheless, one can connect other (compatible, that is common cathodes) types of LED matrices with wires, as this project demonstrates.

Next, there are 2 LED matrices. The left one is a 48mm x 48mm common anode RG, named GMA4688C, for which I couldn't find the datasheet. It is easy to figure out the pin configuration by checking the LEDs with a battery (and resistor, of course). The one on the right is a red LED matrix, 58mm x 58mm in size.

Keep an eye on this page as I will update it periodically. I will soon add other components (LEDs, rotary encoders, ribbon cables, terminal blocks etc) and remove the out-of-stock ones.

Also, if you need other parts for your projects, ask and I may be able to help.

Here is more:

• SD card (empty) boxes

• 16-wires ribbon cables

• DS1307 (either in SMD SOIC or DIP) + crystal 32,768Hz
• 2-pin terminal block
• small and flat speaker, 16 ohms

• LEDs (various shapes, colors and sizes)

• rotary encoder (right angle)

• laser-cut plexiglass plate (3mm thick) for the dual LED matrix shield

• laser-cut plexiglass plate (3mm thick) for the 2416 single-color LED display from Sure