Review of devboards and tools

Boarduino by LadyAda / Adafruit.

My first Arduino-compatible board. It’s the clone of the old Arduino Diecimila (with an ATmega 168P), in a breadboard-friendly format. It’s ideal to start with hardware computing and the breadboard format helps interfacing it with sensors and other circuits.

 

Sanguino by Zach “Hoeken” Smith

I needed more memory and pins than the usual 168P,  so I started using the 644P in the Sanguino, and made it a basis for most of my projects. It has been my main devboard for quite some time, before I made the Mobius Modular board.

 

Teensy 2.0 by Paul Stoffregen

Graciously donated by Paul for the purpose of developing the MIDI library on the Teensy, I’ve been using it mainly for this purpose. It has the same chip as the Arduino Leonardo, meaning it has native USB HID support.

 

Teensy 3.0 by Paul Stoffregen

One of my last acquisitions. ARM M4-powered, this little board can be one of the next big things in the ARM devboard race. I don’t think it might be powerful enough to run an OS “comfortably” like the Rasberry Pi, but a small RTOS should not be a problem.Detailed review here.

 

Arduino Leonardo

I currently use it as a unit test platform for the MIDI Library. The native USB driver in the ATmega32U4 makes it a good board to experiment with native MIDI USB, to create plug and play MIDI controllers and synths.

 

Mobius Modular Motherboard

I made this board to simplify the prototyping of MIDI devices and to be the heart and mind of my Mobius project. It’s using an ATmega 644P and features an IO expander for an LCD screen, as well as a hardware switch debouncer. The central connector breaks out access to 10 GPIO pins.

 

Raspberry Pi

I feel a bit guilty of using it only as a Git/Web home server, but it’s doing the job quite well. It’s running the Wheezy distro without many modifications. I might give a try to the Adafruit Occidentalis distro to play with the GPIO.

 

Texas Instruments Stellaris LaunchPad

The cheapest ARM board I’ve ever seen ($4.99 including worldwide shipping), but comes with limitations, as it’s only a demo board. Still, for that price, you get two ARM M4 chips.

Review here.

 

 Tools

Open Workbench Logic Sniffer by Dangerous Prototypes

Logic Sniffers are useful when debugging digital circuits, but also for firmware debugging: toggle pins when you enter and leave a function to check how much time you spent inside it! It can also analyse most serial transmissions (when setup correctly, took me some time to get it right).

Bus Pirate by Dangerous Prototypes

Very useful little tool to control almost everything that talks a serial language. Scriptable in Python, so with PySide you can make nice interfaces to analyse, control and hack the world. Note: If you plan to use it as an AVR programmer, prefer an USBtiny or something similar, it’s damn too slow.

 

Reflow soldering with a frying pan

Here’s a quick post on how to use a frying pan to solder SMD components.

Here’s what you need:
– A populated PCB with SMD components on one side only (components on two sides does not work with this method)
– A frying pan
– A hob to heat the pan (not induction, see note below)
– A temperature sensor (like a thermocouple), this is not required, but better if you want to keep an eye on your board’s temperature.

The frying pan I used is quite cheap, I got it from Ikea for 2.50€. Any pan would do the job, just make sure the surface is flat. Also, once you used a pan to do some soldering, don’t plan on cooking with it anymore, solder paste can contain lead and other poisonous materials, so keep this one for your DIY stuff only.

Note: do NOT try this with an induction plate. I haven’t tried but the EM field used to heat the pan can be bad for your components. You need preferably a diecast iron hob, I haven’t tried with a gas hob, but I guess it could heat up faster (and would be easier to control).

Once everything is ready, just put the board in the middle of the frying pan, turn the heat to the maximum, and wait.

Keep your eyes on the board, to check when the solder paste starts to melt.

On my experiment, the fusion point occurred at 180°C, starting by the centre of the pan, and quickly moving to the edge. Once you reach that point (you can see the solder paste melting and become shiny), it’s time to remove the pan from the heat (as you don’t want to fry the components).

Leave it to cool in ambient temperature, and there you go!

Mobius – Stereo Loops

In the previous message I was introducing the ability of the Mobius to use Stereo Loops. Here is the module that makes it possible. It uses two Omron relays (one for each channel), and combines both channels in one stereo Jack.
Some effects will have two mono input/output jacks, so a stereo to dual mono cable will be needed in order to use this. In the previous version of the Mobius, it needed two mono Loop modules to switch a single effect.
The Stereo Loop Module

Mobius – New module boards

Here are the pictures of the first few modules of the Mobius Modular:
Stereo IO Board + Mute function on the output:

This module is basically an IO board (Jack <-> internal connector), but with stereo capability (it is still possible to use a Mono internal cable to patch Classic Loops), and a relay to ground the output for the Mute function.
Muting the Mobius is done by pressing Bank Up and Bank Down switches simultaneously for 1 second.
Classic (Mono) Loop v4:

Mobius Modular

Some news on the Mobius project: I’ve been reviewing all my (old) files, specifications and drawings to see if there was a few things I could improve. And yes, there was one.

The Mobius was made modular. That means if you need a looper with 5 loops before the amplifier and 3 in the FX loop, you can have that, as well as one with all 8 loops in a single chain. This allows the Mobius to adapt to the guitarist/bassist’s set. But we can push the idea further.
A few remarks I have been given were that it was not possible to switch stereo effects without using two mono loops, and that there was no possibility to have parallel loops. This is now over! By introducing Stereo Send/Return modules, we can now switch stereo effects with only one module.
This is one example of what the modularity gives. More modules = more combinations, more possibilities.
Here is what I’ve been thinking about so far:
  • Stereo Loop board (Stereo Send/Return)
  • IO board with Mute relay
  • IO board with Mixer (to blend parallel loops on the output)
  • Split board (also called Y module, select an output or an input)
  • Dedicated Amp channel selector (to replace the amp’s footswitch).

Mobius – Working Prototype

I just finished the first prototype of the Mobius, and it works like a charm! Photos and videos to come.

In a nutshell, here are the features of release One (more details below):
  • 8 True-Bypass loops with silent switching action.
  • 2 independent groups of loops + modular design.
  • 32 banks of 4 presets each.
  • MIDI Input & Ouput.
  • LCD display, for naming banks and presets.
  • Live mode.
Okay, so now, how does it work?
This is simple: when you have a lot of stompboxes, and want to switch from a sound to another, it sometimes involves a lot of stomping. These actions can get you out of rhythm, and you might want to keep your attention on your playing, not on your feet.
The Mobius is a helper, it switches automatically your effects for you, when you kick only one footswitch.
What does modular means?
We saw previously that the Mobius has two independent groups of loops. Two inputs and two outputs. You can use this to put some pedals before your amplifier, and the others in the FX loop. as the two groups are totally isolated, there will be no grounding problem. Most commercial loopers have a fixed configuration, but here you can choose how many pedals you want in each group. The Mobius adapts itself to your rig.
What about MIDI?
With the MIDI input, you can remotely control the Mobius from an existing MIDI foot controller. As the chassis is rack-friendly, you can even mount it and switch between your racked stompboxes and effect processors.
With the MIDI output, you can change presets of your MIDI-capable effects while kicking them in the loop. (up to 5 MIDI messages can be sent per preset). The MIDI output also acts as soft-Thru.
What is the Live mode?
Presets are cool when you play a song in a band, when everything should be under control, but what if you want to go off the path for a jam? In the Live mode, each footswitch (including Bank Up and Down) is associated with a set of loops, that you can add or remove from your sound.
For example, you can assign your favorite distorsion to switch A, your chorus to B, both delay and reverb to C, ect..

MIDI Firmware Upgrade

This is an old message I wanted to write about the Möbius: the firmware can be upgraded by MIDI, and it will be as simple as pressing a button on your computer!

Anyway, even though this seems cool, it needs a USB to MIDI converter to connect the Möbius to the computer (PC or Mac), as it does not have native USB connection.