1. Home
  2. Electronics Repair
  3. Identifying an audio ADC

Identifying an audio ADC

I'd like to find a datasheet for an audio ADC used in an inexpensive USB audio capture "card" so as to better understand how to use it and what it can do as a low-frequency oscilloscope. It came from Amazon, sold under the name "DIGITNOW! USB Audio Capture". It seems to work surprisingly well, working with no issues on a Raspberry Pi 4 using the stock RaspiOS version of Audacity. It also works under the latest (not stock) version of xoscope, which had to be recompiled to obtain ALSA support. I'm inexperienced with both programs, so the behavior is somewhat confusing but it does seem worth exploring further.

The seller's tech support carefully misunderstands every question.

It's a one-chip dongle, the single IC is marked IS821S SHO3AO9OAGC

1O2DNMO19

All the O characters look the same, so they could be mixed with zeros. Repeated searches using Google and DuckDuckGo have turned up nothing, does anybody recognize at least a manufacturer?

Thanks for reading!

bob prohaska

Reply to
bob prohaska
Loading thread data ...

paste here the relevant output of the command

lspci -vv

--
Adrian C
Reply to
Adrian Caspersz

The device is USB 2.0 and is plugged into the USB 2.0 ports on the Pi, which aren't accessed via PCI.

lsusb reports

Bus 002 Device 002: ID 152d:1561 JMicron Technology Corp. / JMicron USA Technology Corp. JMS561U two ports SATA 6Gb/s bridge Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 007: ID 2034:0105 Bus 001 Device 005: ID 413c:3010 Dell Computer Corp. Optical Wheel Mouse Bus 001 Device 004: ID 413c:2002 Dell Computer Corp. SK-8125 Keyboard Bus 001 Device 003: ID 413c:1002 Dell Computer Corp. Keyboard Hub Bus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

I tend to think it's probably Bus 001 Device 007: ID 2034:0105 which was the last USB device plugged in.

lspci reports

00:00.0 PCI bridge: Broadcom Limited Device 2711 (rev 10) (prog-if 00 [Normal decode]) Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort-
Reply to
bob prohaska

Yup, my bad :) lsusb it should have been.

formatting link

iSoft Silicon, Inc. (defunct website)

formatting link

"IS-821 USB stereo ADC, stereo line-in and mono MIC-in, I2C interface, 28-pin SSOP pack"

Bit of a dead end, but that site says

"Soft?s audio chips are fully compatible the USB plug-and-play profile. Under most OS platforms, there is no private driver required."

However for electrical specs, pinout etc, I've drawn a blank.

--
Adrian C
Reply to
Adrian Caspersz

Hmmm. The last reply from tech support was "... we don't quite understand what the question you are asking means".

Maybe it's absurd, but it makes me wonder if the device is a Trojan. No....that's too clever....

Thanks for humoring me,

bob prohaska

Reply to
bob prohaska
[top post for brevity]

A keyword search for 2034:0105 led to

formatting link
which led to
formatting link
an obsolete USB audio chip.

Trouble is, that chip employs a crystal and the device I'm dealing with has no crystal. If it's an unlicensed clone it got improved. Perhaps just a hijacked device ID?

Anyway, it was a fun goose chase.

Thanks for reading,

bob prohaska

bob prohaska wrote:

Reply to
bob prohaska

Limited attention span, me thinks.

Oh, well :(

--
Adrian C
Reply to
Adrian Caspersz

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.