MegaBitMeter Assembly Instructions

Preparation

Skills you should bring:

• Basic soldering skills
• Basic Arduino knowledge

You need these tools and materials:

• MegaBitMeter Kit 1 plus your own Arduino OR MegaBitMeter Kit 2
• Small Philips head screw driver
• Small flat head screw driver
• Wire cutter/stripper
• Solder and an electronics soldering iron

Tools needed

In case you want to install your Arduino inside the housing of the meter, which we assume, you also need this.

• Superglue or hot glue
• Xacto knife

You might also just leave the Arduino outside. If you use a longer line to detach your Arduino, you might want to use a switching transistor to protect it. That’s why we added a transistor and another resistor to the kit.

Assembly

Step 1 – Remove scale

Follow the instructions on how to change theMegaBitmeter scale and remove scale completely.

Step 2 – Remove glass

Carefull remove the front frame and glass. Take care to not bend the needle.

MegaBitMeter - Remove front frame

MegaBitMeter - Remove front frame

Step 3 – Change internal resistance

The internal resistance of the meter set for 5V DC when the needle shows 1000Mbps. Depending on your Arduino, the needle might be just a bit below 1000Mbps when set to maximum value. We want to allow for a bit of calibration so we change the internal resistance of the meter. Solder one of the 10k resistors that came with the kit parallel to one of the internal 2k resistors, preferably the one soldered to red wire (important just for spacing later). It should look like this.

Change internal resistance

In case you find it difficult to solder inside the housing, you might want to remove screw holding the wire to the terminal.

Step 4 – Prepare IC socket

We’ll refrain from soldering leads directly to your Arduino’s pins. We’ll solder them to an IC socket instead, to protect your Arduino. Also, it might come handy to be able to remove it from the housing some time. Bend the legs of the IC socket to the outside. That works best by gently pushing them onto a table surface all at the same time.

Prepare IC socket

Step 5 – Carve mini USB jack hole

Chose a point where you want the Arduino’s USB jack to peek out of the housing, preferably the bottom.

Aim well and carve a hole. You might want to remove the moving coil and black backplate for this. Simply remove the four screws on the back of the meter. The hole should look like this, although you can certainly do better than us:

USB jack hole

Step 6 – Wire up the IC socket

Align the Arduino with the IC socket, so that pins TX1 and Vin are sitting in the socket. Pins D10-D13, 3V3 and Vref are free. Now find GND and the PWM pin you want your Arduino to be connected to the meter. By default, that is pin D3. Now cut two pieces of wire, two to three inches (5cm to 7.5cm) long. Strip the ends (2mm) and solder one each to D3 and GND. Solder the one attached to D3 to terminal A (marked on the back). Solder the wire attached to D3 to terminal C. Alternative: depending on your soldering skills, you might also directly solder the 2k resistor wired soldered to terminal C to D3, as shown in the picture below.

IC socket wired up

Step 7 – Insert Arduino and glue in IC socket

Insert Arduino into the socket, so the back of the Arduino (the end showing the six-pin header) aligns with the end of the IC socket. Then glue down the IC socket. It should look like this.

Ardunio - wired up

Step 8 – Install Software

The free and open MegaBitMeter software is available via our download page at http://megabitmeter.de/shop/downloads/. Compile and upload into your MegaBitMeter. When the Arduino inside resets, it will initially set the needle to 0, 200, 400, 600, 800, 1000 and back to 0. You can e.g. use the Arduino IDE’s serial monitor to set values. Set your connection to 9600 (8N1), send a number from 0-1000 as a string and add a newline. Voila!

When using Linux, grab skytee’s script from github. It uses Perl and is used like this with the MegaBitMeter:

$ ./devstats.pl eth0 > /dev/ttyUSB0

Using a different OS? Please contribute!

Step 9 – Calibrate!

Position 0: When your MegaBitMeter is not attached to power, calibrate the 0-position. Use a flat-head screw driver to gently and slowly turn the small black knob in the lower right corner of the meter, so the needle hits 0.

Position 1000: When your MegaBitMeter is set to maximum value via software but the needle does not quite hit 1000, you can adjust this by setting the maximum constant in the header of the Arduino software, e.g.

static float maximum = 249;   // maximum value for 100% meter

Notice: Your meter is made for upright use. It’ll be fine standing upright or slightly tilted, as it is when mounted in the MegaBitMeter stand.

MegaBitMeter Batch 1

If you want to make your own scale, print it on heavy paper or cardboard or ask us to have yours made on a laser cutter. If we actually make a profit on these, a major part will be given to Dingfabrik, Cologne’s newly founded Fablab, to help them raise funds for their own laser cutter. If you come to 27c3, you can pick yours up at the EventPhone booth after buying though our MegaBitMeter Shop. In that case, please use delivery option “pick-up”.

MegaBitMeter - Exchange Scale by Your Own

Step 1 – find the scale slot

Turn your MegaBitMeter to the side to find the black clip that covers the scale slot (fig.1).

Fig.1: MegaBitMeter scale slot cover

Step 2 – insert screw river

Carefully insert a small, flat screw driver in between the clip and the housing (fig.2).

Fig. 2: MegaBitMeter - Open the scale slot

Step 3 – pull away the clip

Carefully remove the clip (fig. 3 and fig. 4).

Fig.3: Remove the clip

Fig.4: Pull away the clip

Step 4 – pull out the scale

Find the notch at the side of the scale sheet, insert screw driver and gently pull the scale out (fig. 5 and fig. 6).

Fig. 5: Remove the scale

Fig. 6: Pull out the scale

Step 5 – Exchange the scale

Exchange the scale and proceed backwards

In the following video you can see the init sequence of the meter when it is connected to an USB port.

MegaBitMeter Scale Preview

After showing you MegaBitMeter and TorrentMeter a month ago, we received a ton of requests from people asking for a product or kit they could buy. Thus we bring you MegaBitMeter as a bandwidth meter DIY kit that will be available at the end of December. We also put MegaBitMeter on Twitter to keep you updated on availability and documentation. We’ve just received the first batch of custom made meters.

The ideas for both MegaBitMeter and TorrentMeter were conceived in different places, yet at about the same time. @pocsascha got inspired to create his MegaBitMeter while working on energy data at ICMP5. @skytee reflected on “the Internet being a series of tubes“, yet certainly all crafted from copper and brass and thus the need for an appropriate “pressure gauge”. Halfway through implementing our ideas, we met and exchanged ideas on how to make scales and drive meters. Now, after getting all the requests for a kit, we make it available.

This is a prototype:

MegaBitMeter prototype

The bandwidth meter DIY kit will have the metal stand you see and the above light blue scale. Soon you can roll your own! If you attend 27c3 or BerlinSides this December, you can get one from us in person. As soon as the shop is up, we’ll post an update on Twitter.

MegaBitMeter

Please stay tuned.

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