Group Buy - Digital Attenuator (Kevin Gilmore)

[kevin gilmore]

here is Kerry's code

http://gilmore.chem.northwestern.edu/oled_mhz15.zip

this supports the original relay board, and the prototype new board, still some software change for the 4 reversed relays for the production board

 

 

Edited April 3, 2016 by kevin gilmore

[Kerry]

The class DATTN will support the new board as well, but needs some tweaking since I had the first rev of the new boards.

[iwik]

Hi Kerry,

Thanks for the code, what oled display are you using.

Les

[Kerry]

Hi Les,

I've used ones similar to these:

1.3" OLED

1" OLED

The code will support I2C and SPI interfaces.

[iwik]

Thanks, thought so and have ordered a couple to try.

Les

[DHTGUY]

I am having issues with the 4d display (uLCD-24PTU) and Arduino. I am trying to intall the 4D systems library in the arduino software, but it says it is not a valid library. The Arduino software is the latest from www.arduino.cc and the library is https://github.com/4dsystems/ViSi-Genie-Arduino-Library. I have tried unzipping the downloaded file to /documents/arduino/libraries and also the menu install a zip file from the arduino software. Both give error messages. Any help would be appreciated. 

 

 

[DHTGUY]

I seem to have solved the problem. The instructions state that the directory should be saved as a subdirectory of library - it has now worked with a subdirectory renamed genie and just the file genieArduino.h in there without the other subdirectories and files. The genie library can now be included in the Arduino sketch with #include <genieArduino.h>. I hope this is of help if anyone else plans to use a 4d display for the digital attenuator

[mypasswordis]

Lmk if you want to see my code, which can be ported to an arduino easily. I am/was using the 3.2" version though

[sorenb]

PROBLEM!

The Mouser order for the Dig.Att. kit ended up having one resistor value backordered: the 6ohms.

I am pretty sure that I checked everything before ordering, and wasn't asked if I wanted partial delivery. I guess Mouser discovered they were out of stock doing my order, which might explain that it took a few days more before they shipped.
This is backordered until late june 6.04ohm
I'll change the order tomorrow to another 6.04ohm that seems to be in stock (hopefully)
If Mouser delivers on time, I'll be able to ship on Wednesday comming week. Sorry for the delay.

I've look at Farnell, Digi-Key and RS-Components and it seems to be hard to find such low value for some reason.

[kevin gilmore]

Parts sourcing is always fun. This has happened to me several times

[sorenb]

2 hours ago, kevin gilmore said:

Parts sourcing is always fun. This has happened to me several times

To add to the fun, everything is now sorted (The MAX4820 has been put in bags using an anti-static mat + grounded arm wrist).
Looks like this:

The Dig.Att. kit will come in a small plastic bag, the MAX4820 in in a antistatic bag, and almost all itmes has been labled A-S, like this (Label C i missing as it is backordered):

The partslist and configuration will be downloadable from here in pdf format, and looks like:

The following has no label as they are easy recognizable:

Label A: MAX4820
Lable B: Capacitors
Lable E: 32 x 49.9ohms

 

 

[Kerry]

The 32 x 50 ohm resistors need to be this ERJ-P08F51R0V.  They are thick film and handle .66W.  The minimum rating for this resistor needs to be .4W.

[sorenb]

15 hours ago, Kerry said:

The 32 x 50 ohm resistors need to be this ERJ-P08F51R0V.  They are thick film and handle .66W.  The minimum rating for this resistor needs to be .4W.

from what I read in the datasheet for  G6KU-2F-Y-DC4.5, the rated coil current is 23.2mA. 
23.2mA  though 50ohm would be some 25mW.
Where does the .4W stem from?

[Kerry]

The relays are single coil and require a voltage in one direction or the other to toggle position.  In order to accomplish this the circuit uses two output pins per relay on the MAX4820 chip.

In the example below from the MAX4821 documentation (APPLICATION NOTE 3288), see how the 50 ohm resistors sit in relationship to the relay.  When you toggle OUT1 low (keeping OUT2 high) the 50 ohm resistor will see a little less than 5 volts (I forget the exact value) across it and about 100mA.  That gives about .5W (I used 4.5V in my math above).  R2 will see much less power across it. 

To toggle in the other direction you would set OUT2 low leaving OUT1 high.  These pulses are very short (a few milliseconds).  By default everything is set high and there is very little power consumption. I've had some programing issues and accidentally left some pins low.  The resistors get hot quickly but can stay in that position without damage.

[sorenb]

Fine.

I'll order the  ERJ-P08F51R0V  today.
Thus the Shipping will be postpone further, probably until friday this week. It will add 2USD to the kit that will include both the 0805 and the 1206 resistor.
 

Sorry for the inconvenience.

 

[wokstarr26]

28 minutes ago, sorenb said:

Fine.

I'll order the  ERJ-P08F51R0V  today.
Thus the Shipping will be postpone further, probably until friday this week. It will add 2USD to the kit that will include both the 0805 and the 1206 resistor.
 

Sorry for the inconvenience.

 

No problems at all. I and  members of this forum is indebted to you for the great amount of work you have put into organizing packing shipping etc for these GB.

I am now publicly  giving you a BIG THANK YOU!!!

[DHTGUY]

I would like to echo that and thanks to Kerry for the explanation. Thanks Søren

[sorenb]

Every package has shipped and the sheet updated accordingly.

For those participating in Dig.Att. Boards, Dig.Att.kit and Über amp boards, your have to look at each sheet to check your final remainder.
Those with negative remainder means you have paid too much and will receive a re-fund of that amount.

Please let me know when the package arrives.

Thanks

Currently double checking payments to be sure that the accounting is right, so don't act until tomorrow, thanks.

 

Edited April 18, 2016 by sorenb

[sorenb]

The 6R04 ohms are marked as "C" (might be confued with those marked as "J") came in small packages of 5 ea, so you might have several marked "C" depending on how many kits you have ordered.
The 50ohms are strips of 32, those Kerry pointed to are marked with a RED stripe.

[iwik]

Kerry,

Been trying to get your code for the i2c .96" oled to work.

The only way i have got it to display is first load an example(adafruit one). Then load your sketch it will work. Remove power and reapply

but the display does not. I have not connected it to the attenuator yet. I think the main code for att is starting as the red Led on the 

Nano flickers with the encoder. Just seems that the display wont kick into life. i am wondering if the example code is somehow

initialising the display. Im not any good at coding so any help would be appreciated. The adafruit example i used starts every time

i power up the setup. Thanks

les

[Kerry]

Hi Les,

I've been a little focused on the amp build.  Just sitting here listening to it now and trying to remember about the code.  I just downloaded the latest 1.6.8 version of the IDE.

Let me play a bit and see what's going on.  My display is working as is, but I know there are a couple of different controller chips used and it's possible yours is different.  Take a look at the description of the display.  It will likely tell you what the controller chip is.  The code is currently set to support the SSD1306, but I also support SH1106.  Let me know.

EDIT:  I just sent some updated code to Kevin to post.

EDIT 2: I'm not sure that this will run on a Nano 2.0, but should on 3.0.  I've got some large display fonts I'm storing, so probably needs the ATmega328, which is what I've been testing on.

Edited April 22, 2016 by Kerry

[iwik]

Thanks Kerry,

Went with the nano so small enough to fit. Will try new code when posted and let you know.

Now get back to enjoying that masterpiece of yours.

[kevin gilmore]

latest code from Kerry works with current Arduino compiler, but still does not have the code for the flipped relays

http://gilmore.chem.northwestern.edu/volumecontroller.zip

 

[iwik]

Kerry,

Still no luck, i am using a nano with Atmega328 and my display is a ssd1306. The new code would not compile on 1.6.7

ide like the last one did, so upgraded to latest. I still have to do the same to make it work. But now the V in volume flashes at a bout 1hz rate.

 

[Kerry]

I just bought a Nano v3.0 last night so I can try it directly.  I should have it by tomorrow.  Let me try it and see if there needs to be any tweaking.

Also, check your connections.  I have SCL to pin A5 and SDA to pin A4 on the Arduino.

All I did to the code to get it to compile on 1.6.8 was to add a forward reference to the function SetVolume in the top part of the code. 

There's a lot I want to clean up in terms of how I want the code structured.  This is just to test the boards and make sure they function properly.