Duggle

The ULN output low is around 0.7V or so which does reduce the brightness (compared to driving them directly from the shift register), however you can use a lower resistance like 100 or 47 ohms to drive the LEDs much harder. There is a limit to how bright the LEDs can go though, due to the LED devices saturating.

Yes, this will work. Alternatively, feed a 5V input to the core (from the regulator) and leave the 7805 in place, it doesn't hurt to leave it there.

Hi kpete, have you searched ebay? There are very many DC DC circuit boards for just a few bucks (in some cases including postage). One suggestion is to use such a switch mode regulator to provide your 5V on the core (simply replace the 7805 with the switch mode PCB) and leave the 3.3V regulator as is (it won't get hot with a 5V input). I've done this works fine, cool as can be.

Its simple really. If you consider the track carrying the signal and the ground, a pair of conductors, the current flows in a loop from the signal source, down the wire, into the input of the receiver, then in the ground path back to the supply. By "keeping close" the signal and the ground return tracks, the inductance property of the circuit is minimized so that the signal integrity is better. When talking of minimizing the loop area, it is the physical area created considering the path of current. A quick google yielded this reference: http://books.google.com.au/books?id=qeWWXvuAXXoC&pg=PA161&lpg=PA161&dq=signal+integrity+loop+area&source=bl&ots=DwrZuxjpAA&sig=jPSFMB_2fMMhU3941Nei99cgPU4&hl=en&sa=X&ei=7AHSUtiaH4iPiAf3z4DYCQ&ved=0CEUQ6AEwAQ#v=onepage&q=signal%20integrity%20loop%20area&f=false

I don't have anything fresh to add right now. As a general rule: try to minimize the area of the loop formed by the conductor and it's ground return path. That means trying to keep the signal close to the ground from transmission to reception.

Did you set the midi receive channel on the XV-2020?

Yes, there is an additional step. You need to upload the midibox application itself, in this case midibox KB. When you've done this it will no longer say "MIOS32 bootloader" in the message but the name of the application.

I'm not sure of the bandwidth specs you mention. Is the second figure the sample rate? If so the first one. Otherwise the one with the bigger bandwidth (200MHz). But either should be sufficient.

Novski, are you seeing the same initialisation problem as KUI?

As I understand it, optical are more expensive but very long wearing, such as within a machine or device which rotates continuously. Slotted /flat is referring to the end of the shaft which the knob fits onto. This brings up the subject of knobs (which can cost more than the encoder). Because almost all knobs you see have markers on them (making them inappropriate for encoders) they can be hard to find. I have found a cheap knob that looks o.k. that has an insert (available in different colours) that can be removed sanded down to remove the endented marker, then reinserted. These for are for $0.65 (AU) minimum of ten. These use flatted (which is probably more common).http://www.jaycar.com.au/productView.asp?ID=HK7707 The Bournes encoders are rated at minimum 100k full revolutions. This is a lot of tweaking (do the math) :smile:

That's a big supply. So the regulated 5V for the OLEDs is coming from the core?

@KUI, Are you powering from USB? If not, I suggest a power supply that is rated with a higher maximum current. It may be that with the electrical load of the extra bank of displays the power rail to the displays is rising too slow and interfering with their initialisation.

One procedure you could follow: Go back here Download the data sheet. Look at the pad spacings on the mechanical diagram on the second page. This is what you need to fit the PCB. (I'm assuming that you'll be able to get hold of 4 x Firlightiii's PCBs) Go to this page: parametric search of encoders from digikey Set the heading "Detent" to "No" and the heading "Built in switch" to "Yes". You'll see a whole bunch that fit this criteria. The Bournes one(s) will fit the PCB footprint. Check it against the datasheet (which also explains the ordering code, "How To Order", btw). I'm sure you'll be very happy with the performance of these with the MIDIbox NG firmware. The ones with 24 pulses per revolution work really well. NG has a range of "speed" settings that you will use in your script to suit the parameter you are controlling.

Mouser, Digikey and the german one Riechfelt (or whatever, sorry Im mobile atm.) all have webshops and extensive search engines and datasheets to check the specs. You can buy small quantities. Use the example I provided as a guide. The configuration you want is out there.

Hi Tom, thanks for the info re: remapping Push. I'll look into this. Your application that makes use of static mappings is particularly straight forward. Have you read the articles linked to in post#1 of this thread? Also Midibox NG and DIN (the kits are available from SmashTV for this) The encoders (detented with push switch) are here (as an example). BTW I bought these, but haven't tested these yet, but am confident. The encoders (nondetented without push switch) here I used these, and they work well, very smooth. My advice: be patient read a lot (there is plenty to read) and enjoy. BTW; the hardware designs have been made so that no particular experience is necessary (i.e newby friendly!) Of course, as in all things, a willingness to learn is essential.

Welcome! I can't answer all your questions, but I can answer few. No programming required. You'll base the project on Midibox NG firmware which you flash into the LPC17 core module. The script which configures your controller is a text file that lives on the SDcard attached to the core. This is the part that allows you to define exactly what all the controls do, and how the LED rings behave in relation to the feedback they receive from your DAW (Ableton). These are available no problem. I have made a very similar panel based on PCB's similar to TK's photo above. It will work USB powered. In addition to the encoder PCBs, you need to connect to 2x DINx4 PCBs that will give you the 64 push switch inputs. My advice is to ask Fairlightiii if there are any more Encoder LED Ring PCB's available. A lot of the other stuff is avalable at SmashTV's shop . He gives very good service. You can save a lot of money by sourcing the encoders from traders on Ebay(e.g. $0.60 each, free postage). Make sure you research the specifications to get exactly what you want. I have undetented encoders in mine and they are "butter smooth"! MIDIbox NG allows the customisation of the "speed" of the encoder action that will give you the response I think you are after. There is much for you to read up on (go to uCApps.de) and also the WIKI article on the encoder LED rings PCB. Lastly, I have just started my journey with Ableton Live 9 and a "Push" control surface. I am blown away. I use REAPER and plan to sync Ableton via Rewire. I'll be really interested in how you use Ableton with MIDIbox.

I assume novski found them necessary to make his displays work. I've found that this sort of thing can make a difference, but it really depends on the layout. It won't hurt to keep them for displays 1..8. It may even be necessary in your particular layout. I found that they reduced display corruption when I built a Midibox NG with 24 off character LCDs recently. It is a large panel with a lot of wiring and for reasons I won't go into here they were at one point only marginally functioning and the resistors in series with the CS lines improved matters. This does makes sense from a noise coupling viewpoint.

It the 220R are already on the DOUT PCB, then no need to add more. Although they are not shown on the first 8 displays, there is no need to remove them if they are already on the the DOUT you are using for the first 8.

Its a hard call to make as you may not end up using it very much. However, if you experiment and build electronic hardware from time to time they can be very valuable! I bought a tektronics compact LCD one for about $1600 all the way back in 2000. It still works perfectly. I have used it for work as a contractor and of course electronics, music and midibox projects very much over the years. Coincidentally it's the same type as what TK uses. Sorry I've forgotten the model number, it's actually at my work at the moment and I'll not be back there for a few days. As far as bandwidth is concerned: the rule of thumb is 5x the sample rate of the highest frequency signal you want to observe. So if there is a 10MHz clock you may want to be able to see ringing that is at 100MHz so that the scope samples at 500MHz. Probably a CRO quoted as 200MHz BW would be adequate. I do remember that my CRO does Gigasamples per second. So it's really hard to provide general advice. I can say if you really love electronics and want to do a lot more in the future they're a great investment and actually essential for serious work in this area. The laptop or computer connected dongle may be a cheap way out and get results in the short term, but in the long run you want a dedicated tool.

If things are set up so it is easy change the R, then simply experimenting with different values may be enough to terminate optimally. The last time I went through a similar situation I considered putting a 500R trimpot on the clock line wired as a rheostat (variable resistor). I didn't need to in the end. The advantage of using a CRO is that you can see why a termination is working, and how well, possibly resulting in better margin of error (less likely to start seeing artifacts/failure in unusually hot or cold temperatures, for example). If you cannot see the waveforms (i.e. no CRO) then I would establish the minimum and maximum R that works (based on say 50R increments, as I suggested earlier) then settle for the midpoint (min+max)/2.

Great! When you get hold of a CRO you will be able to "fine tune" the value of resistor. Also take a look at SDA as well. Basically when you see "ringing" increase the termination resistor. When you see "slow edges" try by decreasing the resistor. In fact, even before you have a CRO to look with, you can try a few different values, say in about 50Ohm increments. At a certain point you will lose all communication. An easy place to solder the resistor is by cutting the wire close to the IDC connector at the core and soldering the resistor in there.

Have you tried series termination? This would be more likely to improve things in my experience. I've had great success resolving issues with DOUT chains by doing this. Start by trying a 100Ohm at the driver (core) in series with SCLK.

Wonderful! The feedback Rf determines the gain, this changes you're range from about 0.55V to 3.3V, and the part of the network of around R1 determines the offset (which is very small as your minimum 0.05V is very close to 0V anyway). So if your're seeing very close to 0V up to 3.3V as you press the sensor through it's range, then it works as designed!

Glad to see you're making progress. What is the voltage range on pin 1 of the LM324?

Yes, your're on the right track. Make sure you wire the trimpot (R1) as a variable resistor (wiper and one end are used).