IR proximity sensors to Eurorack and Max/msp

Projects General Guidance
1

Hi everybody.

I seek help mainly on the electronics around the arduino and connections to power and eurorack. The coding is not an issue. It might be later, but first things first. I would like to understand the electronics around the Arduino and the sensors before I start, because I live in a small country in the middle of the Atlantic ocean (Faroe Islands) and we don’t have an electronics store to pop in to get parts of the shelf. Everything is ordered online with weeks of delivery, so I would like to have all the parts in place before making the order.

Overview of the project. I’m planning to use two Sharp proximity sensors connected to an Arduino Micro and have the data transmitted to computer via usb (easy) and Eurorack modular control voltage via two 3,5 mm TS jack. One for CV and one for Gate voltage. I would like to have 5 potentiometers controling the output signals.

  1. scale/gain of the CV
  2. the offset of the CV
  3. slew rate up
  4. slew rate down
  5. gate threshold.

And this is for each proximity sensor. So 10 pots and 4 3,5mm jack’s

I would like to have this mounted in a housing that I can power with a power adapter 9-15 volt DC. If anything between 9 and 15 can work, that would be great.

The sensors I plan to use are a SHARP GP2Y0A710K0F and a SHARP GP2Y0A41SKOF. As I understand, I will need a by-pass capasitor of at least 10uF to stabalize the power to the GP2Y0A710K0F. And I need to protect the Arduino from shorting the analog pins when connecting the 3,5mm jack. TL07x seem to be recommended.

Questions:

I need to scale the Arduino analog out to Eurarack levels. 0-10 V and be able to offset that range to -5-5 V. Would it be possible to have the opamps do that controlled with two pots? And would it be possible for the Arduino to get a reading from the pot so I can send the reading via USB?

Then there is the external power supply. I have never used an Arduino with external power supply. Only usb powered. So I need to do some research there. But I’ll need to provide power for the sensors, the arduino micro and the opamps.

That’s it for the first post. I’m hoping this thread will provide a parts list and good suggestions for me and anyone interrested. I haven’t gotten to the housing yet. First I’d like to see, what I’ll have to fit in there and then I’ll figure out how to house it.

If anyone is curious, I plan to use this for music performace where I can use proximity data to control parameters in synths and Max msp environments. The Koma Kommander is very similar to what I wan’t to acheive. KOMMANDER – CV/Gate Motion Controller – KOMA Elektronik But I would like to have my two sensors not facing in the same direction and I would also lIke to have the extended range of proximity sensing.

2

Difficult to work out exactly what you want, especially when Eurorack is not familiar. 19" racking, yes.

Break it down into easier to understand modules or sub projects so readers don't have to.

3

I’ve used the GP2Y0A21YK0F which has a range of 10-80cm. Although the output is analog it only takes on discrete values as if it was the output from a DAC. Since the output is nonlinear the resolution changes with distance. It works OK with a white card that is perpendicular to the sensor, but anything else was iffy, especially at the longer distances. Overall I was disappointed with the device.

4

Thanks for a clearly presented post, and Imthinkmyoull get there, but it’s going topologically be a learning curve.

There are going to be quite a few more questions, but the best starting point will be to break the functional design into clear independent blocks that you can test independently - this is particularly important since you are quite isolated for the source and supply of parts,.

Work on a clear spec and functional requirements documents, followed by a block diagram and later, a detailed schematic to tie the plan for your first prototype,
The pse will minimise your need for multiple order & assembly cycles, and provide clear milestones for review and discussion,

5

Thank you all so far.

By popular demand, I’ll break the design down to blocks :slight_smile:

Think I’ll get my head around the power section. Eurorack uses 0V-10V (or -5V - 5V) control voltage and I’ll be using op-amps to gain the arduino analogue output to that. Also to protect the arduino from shortcutting when inserting the jack from the Eurorack. I’m looking at the TL074 op-amps. From what I understand of op-amps, they can’t deliver more voltage than they get from the power supply. Will I then need a 20V power supply and split it to a -10V and a 10V with a virtual ground? And what would be the best way of getting 5v to the sensors and the arduino from there?

6

After some additional thinking, would this work:

Using a 7-12 V power supply for the Arduino and splitting that power to get a -6v - 6v with a virtual ground to power the op amps. The configure an op amp to shift the 0 - 5 V arduino output to -2.5 - 2.5 V and have another op amp to gain that to -5 - 5 V with a pot and have another pot to offset the voltage to 0 - 10 V. Would this be possible, to have an op amp with +/- 6V supply voltage to deliver up to 10 V ? If not, would it be possible to have some of the op amps running on 12V and have them offset to voltage?

If this approach works it would eliminate the need for different power supply or converter for the Arduino and the op-amps. I will gind time to write up how I imagine the circuit would look like a bit later.

7

So you still think the GP2Y0A710K0F will work?

8

Yes. I’m not looking for accuracy. I’ll be converting the procimity data to control voltage wich in turn will control aspects of my synth. Close=loud, far=quiet or close=many notes, far=few notes, and so on.

9

OK. It can easily do close vs far.