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AT2380v2 2Ch Digitally controlled Stepped Attenuator

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#47
Hello all,

I released today the new v0.23 CPLD firmware for the AT2380 that add :
- Firmware version display at startup
- Calibration mode.
- Relays fast mode operation (for audio volume control applications)
- Bluetooth UART mode attenuator control/measurements
and others code improvement and bugs fix.

Because of these many modifications, i have made a new design folder (v2.1).
A download link has been sent to all PCB buyers this day.

Note that the only change in bom file is to add 2x5pin header to allow jumper mounting.
Schematics as been updated only to show some new annotations.

So, manual is updated to include all new features and some corrections.
Building procedure has been also updated.


Frex
 
#48
Hi,

Mouser order arrived, and I stole an hour of sleep to start the soldering...

This is the most complicated and challenging project in my DIY career so far, but Frex went a long way to put an excellent package together, thanks for that! The documentation is outstanding! A professional documentation couldn't be better and more in-depth, and this is a hobbyist effort for no profit at all. Your commitment to the DIY community is most generous!

So far, I soldered the ICs ... that CLPD in TQFP-100 case was a real challenge. I could not succeed with hand soldering, there was one short between pins that I couldn't get rid of. In the end, the cheap chinese hot air station that I had bought out of curiosity, and incredile amounts of flux solved the problem!

I believe I found one mistake in the BOM, U8 is supposed to be SOIC-8, but the Mouser part number is for VSSOP-8 case (BOM: 595-THS4531IDGKR , should be 595-THS4531IDR or 595-THS4531ID).

I hope I can continue tonight, sleep is precious, but curiosity kills the cat....


Best regards,

hallodeletue
 
#49
Thanks for the heads-up on U8. My Mouser order literally just arrived (with VSSOP-8). Took nearly a week to ship evidently due to the large number of line-items after combining two big projects! They were nice enough to upgrade to overnight shipping. I think I'm going to stencil due to the TQFP-100 pitch.

BK
 
#51
Back order

All -

The following two parts are back ordered from Mouser and I can't find a comparable substitute on their site. The latter is delayed until next Christmas! Can you recommend a substitute?


81-GRM219R71E105KA8D
GRM219R71E105KA88D
1.0UF 25V 10%
Murata Multilayer Ceramic Capacitors MLCC - SMD/SMT 6 6
MAR 30, 2018

81-GCM188R71C105K64D
GCM188R71C105KA64D
0603 1.0uF 16volts
Murata Multilayer Ceramic Capacitors MLCC - SMD/SMT 8 8
DEC 26, 2018

Thanks in advance,
Jim
 
#53
Hi,
I substituted

GRM216R61E105KA12D
C0603C105K4RACTU

I have a question concerning C5, it appears twice in the BOM, one time as 10 uF/10V (together with C37, GRM21BR71A106MA73L), and the other time as 1uF/25V (together with C6, GRM219R71E105KA88D).

According to the schematic, it should be 10uF/10V, so I guess thats the save bet. If I understand it correctly, C5 is used to define the high-pass corner frequency of U1's internal offset compensation. 1uF would give a 3dB corner of 60 Hz, whereas 10uF equals 6 Hz. I guess that 10 uF is the correct value for audio applications. Is it right to assume that chosing 1uf would filter out mains hum?

Best regards,

hallodeletue
 
#54
Hello hallodeletue ,

Thanks to have pointed out this error.
C5 is a 10uF (GRM21BR71A106MA73L) not a 1uF.
There is no need to filter mains hum, and it is a single pole so the attenuation will be not significant.
Note also that you will get amplitude error for low frequency input in tracking mode operation.

C8,C9 are noted in BOM 1uF/25V X7R 0603, but the ordering reference is a 16V model.
The code is ok, this caps is on 1.8V rail.

The 22uF/10V cap C29 is back ordered on Mouser but can be replaced by
from Mouser and in stock : 81-GRT21BR61E226ME3L
It is equivalent (X5R instead of x7R but no issue).

The S1 rotary encoder is also back ordered (but available again very soon) and
it is in stock at Digikey here : EN11-VSM1AF20.


Frex
 
#55
Stencil should make board assembly easier/better!


BK
 

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#57
Hello Frex,
I hope not bothering you but I, at least completed soldering and beeing a complete noob I would appreciate a link to the appropriate programming software (Quartus ?) and other software needed to program the CPLD . It seems that there are numerous version and add on (in) available
thanks in advance
Jean Claude
 
#58
Hello,

You can use this one.
About software, you can use any Quartus version supporting MAXV devices.
I personally use Quartus 16.1. You can download it here.
You must download Quartus Prime Lite Edition (Free) - 1.7 GB
and then install also MAX II, MAX V device support - (11.4MB).
Note that you must be registered to intel to download files.
Regards.


Frex
 
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