Creative NachBau V02-Board Assembly Instructions Manual

NACHBAU Assembly Instructions

Author: Christian Aschof, cascho@mac.com

Version 0.4 from August 10, 2012

Translator: Hesky Fisher, hesky@wyolum.com

These instructions are for:

The NachBau_V02-Board was built

from:

to:

To-Do:

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Forward

These instructions are for the assembly of a NachBau_V02-board.

The NachBau_V02 (NachBau is German for „replica“) is an LED matrix

display driver. This means that one can use it to control a 16x16 LED

matrix display (i.e. 256 LEDs). The LEDs are driven via multiplexing.

The NachBau_V02 board also has clock support. It has a battery-backed

real time clock and can update the time, based on the DCF77 time

signal from the German National Physics Lab in Braunschweig.

Finally, the board can be chained: one can connect multiple boards

and control several 16x16 LED matrices to make larger displays.

The board is therefore especially suitable for:

• Clock projects, such as word clocks, clocks with scrolling text, binary clocks, etc.

• Large-format versions of games, such as Pong, Maze or other low resolution games (see also the Mignon Game Kit from Olaf Val).

• Display projects, such as tickers, temperature displays, advertising, etc., especially when the displayed text is time dependent (e.g., automatic

displays of „We're open“ / „We're closed“ driven by opening hours, etc.)

The idea for this board came from the QLOCKTWO replica project. There are instructions at http://code.google.com/p/grosses-bastelwochenende on

how to assemble a word clock from many parts. To somewhat tame the chaos and failure rate, Justin and Anool from WyoLum redesigned and streamli-

ned the boards. The three boards from that project (control board, anode multiplexer, cathode multiplexer) plus the Really Bare Bones Board from

Jee-Labs/Modern Devices are now combined in this one board.

The boards and the associated circuits are released as Open Hardware. The plans and Gerber les can be found at http://code.google.com/p/clockthree/.

The ATMEGA328 chip from the kit is compatible with Arduino and can be reprogrammed for use in your own projects using an FTDI cable and the

Arduino IDE. Sample code can be found at http://code.google.com/p/grosses-bastelwochenende/.

Cool, no? So then: Warm up your soldering iron and let's go. Or as Yoda already said in the QLOCKTWO Replica project:

May the force be with you.

Safety Notices

Soldering irons, hot glue guns, hot glue and hot-air

guns are hot, as the names imply. Cleaning agents,

especially rubbing alcohol, are ammable.

During assembly you will be exposed to voltages

and current. If the NachBau_V02-Board is powered

by a battery or DC adapter (the recommended

way), then this won’t be a problem. However, using

a built-in AC power supply exposes you to mortal

danger.

The assembly of the NachBau_V02-Board is dange-

rous. Carpet knives, scalpels, glass edges and drill

bits are sharp. SMD tweezers and drill bits are

pointy. Snipping o the legs of components send

sharp pieces of wire ying around. These can harm

your eyes.

If you use „super bright“ LEDs then you must never

look directly at the LEDs, especially while uploading

the rmware, since random lights may turn on due

to junk data in the shift registers.

An LED matrix driven by multiplexing operates at

high frequency and causes electromagnetic interfe-

rence in the form of radio waves. This currently

interferes with the DCF77 receiver, which we plan

to x. For other things that might be disturbed by

such interference (e.g. pacemakers) you must take

your own precautions.

Solder fumes, cleaning agents, sanding dust, glue,

paint, etc., are almost always toxic.

In conclusion: The assembly of a NachBau_V02-Board

is in every way dangerous. It is advisable to wear eye

protection, gloves and to have a rst-aid kit ready.

So, man or mouse? Right. The life of a tinkerer is

dangerous in and of itself. So, use your head, work

carefully, and press on.

Version history

Links

V 0.1 24.4.2012 Created.

V 0.2 2.7.2012 Resistance values adjusted (the colors were wrong).

V 0.3 11.7.2012 Page 8: Adjusted resistor values; Page 15: Claried empty resistor slots.

V 0.4 10.8.2012 Removed color values of resistors.

Current rmware and related les: http://code.google.com/p/grosses-bastelwochenende/

Wyolum (distributor of the board and kit): http://wyolum.com

Schematics and Gerber les: http://code.google.com/p/clockthree/

Author‘s blog: http://christians-bastel-leben.blogspot.com/

Arduino: http://www.arduino.cc/

Jee-Labs (RBBB/USB-BUB): http://jeelabs.org/

Reichelt: http://www.reichelt.de/

Pollin: http://www.pollin.de/

Layout of the board

Real time clock (DS1307, crystal, cattery holder for CR2032, pull up resistors)

ATMEGA328-MCU with crystal/resonator

Power supply (voltage regulator, power jack,

capacitors, blocking diode)

Status LEDs with

resistors

5 buttons (Mode, H+, M+,

Enter, and Reset) with pull

down resistors

Anode multiplexers (shift

registers, Darlington arrays,

ltering capacitors, terminal

block)

Cathode multiplexers

(shift registers, current

limiting resistors,

terminal block)

FTDI and ISP

Headers for

rmware

updates

3.3 Volts

for DCF77

Prototyping

Area

Photoresistor

and resistor as

voltage divider

Stack-L

(for larger

matrices)

Stack-R

(for larger

matrices)

A few words in advance...

Components are usually soldered onto a circuit board in height order, shortest rst. This allows you to ip the board and have the component rest on

the table with the board on top of it. Otherwise, when you ip the board for soldering, the board will rest on the taller components and the shorter

ones will just fall out.

The downside of this method is that you have to assemble the entire board before testing. If you made a mistake, it can then be hard to nd.

In this tutorial, we are attaching components grouped by functionality instead. We will then test each section separately. When attaching compo-

nents with long legs, just bend them so they stay attached when you ip the board. You can use masking tape to keep other components in place

while soldering.

Many features of the board are optional. To use it as a 16x16 LED matrix driver only the ATMEGA328-MCU along with the anode and cathode multi-

plexers are required. The rest is optional:

• To use it as a clock you will need the DS1307 real time clock. With the battery backing, it will continue to keep time when disconnected from a

power supply.

• For automatic time updates you can add the DCF77 receiver. The time will update any time it receives a valid signal. The receiver can be left on

permanently (by using the jumper on the receiver terminal strip to connect P to -) or you can connect P to D and, which connects pin D13 on the

ATMEGA328-MCU to PON, and you can set the pin high to turn the receiver o when you like.

• If you have a stable 5-6 volt supply, (e.g., a USB power supply or batteries), then you can connect those directly to the voltage regulator. If you

want to use an external power supply, then you need to set up the voltage regulation section and then the board will be able to take 7-12 volt. By

the way, you can use the jumper next to the anode multiplexers („5V<->Vext”) to send the external voltage to the Darlington arrays to increase

the brightness of the LEDs. But this is for experts and is only briey covered in this tutorial.

• You can add a photoresister to control the brightness of the display based on the ambient light level.

• You can add the FTDI port and ISP header to program the microcontroller.

• Finally: Instead of the DS1307 you can also use a Chrono-Dot or a DS3231N. Stack-L and Stack-R can be used to chain boards to power a larger

display. Neither is supported with the current word clock rmware but it wouldn‘t be that hard to add.

Step 1: The ATMEGA328-MCU

Required parts: Placing the parts:

1*ATMEGA328

1*crystal 16 MHz

2*C 22 pF

1*resonator 16 MHz

1*crystal und 2*C 22 pF

1*resonator

1*ATMEGA328

(make sure to align the notch!)

The 16 MHz resonator is

soldered into these

holes.

The 16 MHz Crystal is

soldered into these two

holes. Then you also

need 2*22 pF capacitors

(C11 and C12).

Right at the start you have a tough choice to make. Do you use a 16 MHz resonator or a 16 MHz crystal with

two 22 pF capacitors as the clock for the ATMEGA328-MCU? One tip: They‘re the same. A resonator consists of a

crystal with two capacitors. You should choose whichever one is easier to nd.

Make sure to line up the small semicircular notch in the short side of the ATMEGA328 with the mark on the

board.

Experienced solderers can attach the MCU directly onto the board. Beginners should use the socket (Make sure

to line up the notch in the socket as well) and later add the MCU. This is because the MCU is more sensitive to

the heat from the soldering iron. This will not aect the overall height of the board because there are still taller

components that aect the overall clearance.

We don‘t need the small solder pad labeled „X1“ so we will ignore it. It is there because some crystals need a

ground plane.

Testing the ATMEGA328-MCU (preparing the power supply)

In order to test the MCU we rst need power. We have two options: the FTDI connector or an external power supply. Let’s rst try the FTDI option

since we’ll need some of the same parts for the external power supply.

First, we’ll solder on a jumper that we can use to choose between USB and external power.

Required parts: Placing the parts:

1*Pinheader

(3 Pins)

1*Jumper

We use this jumper to choose the power

source: either the FTDI connector (Position:

USB) or an external supply (Position: WALL).

Then we‘ll attach the power LED so we can

tell when the power is on.

1*red LED

1*1 kOhm

Attention! The LED has a long

and a short leg. The long leg

should go through the red

hole in the diagram and the

short one through the blue hole.

Testing the ATMEGA328-MCU (power via FTDI)

Required parts: Placing the parts:

1*Pinheader

(6 Pins)

1*100 nF

1*10 kOhm

For the FTDI connector you can use either a straight or right-angled header, whichever you prefer. The pin header and capacitor are only

needed when using an FTDI cable or ISP header to program the ATMEGA328-MCU.

The resistor by the reset switch must be added even if you don’t intend to add a button. If it is not, then the Reset pin of the

ATMEGA328-MCU will hang and the microcontroller will constantly reset itself.

If you have an FTDI cable or a USB cable and a USB-BUB (e.g., from Jee-Labs), then you can now test the ATMEGA328-MCU.

Open the Serial-Monitor in the Arduino-IDE with the right settings (Serial-Port: something with „USB“ (The name is dierent on every system),

Board: Arduino Duemilanova; Serial speed in the monitor: 57600) then the MCU will output:

Qlockthree is initialazing...

... done and ready to rock!

The red power inicating LED will only light up using an external power supply.

Testing the ATMEGA328-MCU (external power supply)

Required parts: Placing the parts:

1*power Jack

1*voltage regulator

1*blocking diode

2*100 nF

2*100 µF

Solder the green and yellow LEDs plus their 1

kOhm resistors just like you did the power

LED. Here too, place the longer leg of the LED

in the hole marked red in the diagram. These

LEDs and resistors must be soldered on

regardless of which power source you use.

Make sure to align the voltage regulator so that its metal plate will lie on the rectangular solder

plate. Face the side with writing toward the real time clock area and face the metal part toward

the open source hardware logo.

The large capacitors (100 µF) have polarity. The leg with the minus sign goes in the hole with the

mark (The two capacitors‘ negative poles face each other). There are two holes for the other leg

to handle capacitors with dierent leg spacing.

For testing purposes, when you use external power (jumper to the WALL position) then the

yellow and green LEDs will quickly blink three times.

Step 2: The DS1307 real time clock

Required parts: Placing the parts:

As with the reset button you

must add on pull down resistors

(10 kOhm) to the H+, M+ and

Mode switches. If you forget

then those pins will hang and

the actions will constantly be

triggered. The DS1307 won‘t

work correctly since the time is

constantly being set.

2*4,7 kOhm

1*100 nF

1*clock crystal

1*DS1307

1*battery holder

and CR2032 battery

Make sure that the notch on the DS1307 lines up with the mark on the board.

Before soldering the battery holder, tin the round pad with the minus sign to make sure the battery makes a

good contact with the board.

The time crystal is soldered so that, when bent over, the housing will lie on the long rectangular solder pad. In

contrast to the crystal next to the ATMEGA328-MCU, here we do need the ground plane (Those interested in

the details should google “dallas real time clock crystal considerations.) It is essential to solder the housing of

the crystal to the ground plane. Using additinal soldering ux helps here...

For testing purposes, if the clock is properly attached then the green LED will start blinking once per second

(after the initial three fast ashes).

Step 3: Prepare the DCF77 receiver

Required parts: Placing the parts:

1*220 Ohm

1*3.3 volt zener diode

pin header and jumper (optional)

The zener diode and the 220 Ohm resistor make a voltage divider to produce the 3.3 volt that the

DCF77 receiver requires.

The pin header and jumper are optional. They switch what is connected to the PON pin on the

receiver (that can be used to put the receiver to sleep). If you attach it to ground, then the receiver

will stay on permanently. Alternatively, you can connect it to pin D13 of the ATMEGA328-MCU, so

you can put the receiver to sleep whenever you want.

The pin assignments on the board correspond to the receiver by Pollin. Other receivers might

require extra circuitry which can be placed in the prototyping area of the board.

If the receiver has a good signal then the yellow LED will blink once per second (but a shorter blink

than the green LED). A DCF77 receiver can take up to a half an hour before it is ready!

3.3 volts from

the voltage divider

Ground

Data

PON

These two

pins are

connected.

Step 4: The anode multiplexer

Required parts: Placing the parts:

This resistor (4.7 kOhm)

must be soldered on

before the rst test of

the matrix. It sets the

output of the shift

registers before they

are initialized. Otherwi-

se, the LEDs will light

uncontrolled and can

burn out.

2*UDN2981A

Darlington arrays

2*74HC595

shift registers

4*100 nF

1*pin header

and Jumper

Just like all the other chips, make sure to line up the notch on the chip with the mark on the board. The 74HC595

shift registers and the UDN2981A Darlington arrays face opposite directions.

You can use the jumper to change the voltage input of the Darlington arrays. If it is set to „5V“, then they will get the

same 5V as the rest of the board. If it is set to „Vext“ then it will receive its input directly from the external power

supply.

You can use this to change the brightness of the LEDs. However, if you use this then you must gure out, on your

own, what value to use for the resisters on the cathode multiplexer (R12-R27). You would need to use an oscillo-

scope to measure the voltage on the output of the Darlington arrays and calculate the appropriate resistor value

using one of the many online resistor calculators. As you can see, this is an advanced option intended for experts.

Step 5: The cathode multiplexer

Required parts: Placing the parts:

2*74HC595

shift registers

2*100 nF

16*6,8 Ohm

or short links

Make sure to line up the notch on the 74HC595 shift registers with the mark on the board.

Here you have another tough decision. Many hobbyists drive their matrix without resistors. At rst this seems odd. We all know that LEDs need resistors.

However, the Darlington arrays have resistors so these may be enough and there have yet to be reports of LEDs burning out. Especially, since the silver

wires that connect the LEDs in the matrix are good heat conductors and good heat removal is essential to the long life of LEDs. So thrill seekers can

replace the resistors with wires or jumpers. Those who want to be sure can add the resistors from the kit. These are small, only 6.8 ohm.

Those who set the jumper to „Vext“ must adjust the values of these resistors as previously discussed.