GM-800 A2B Architecture

[GuitarBuilder]

Elantric - I know you've looked inside the GK-5 enclosure showing the AD2428 transceiver. Have you had a chance to look inside the GM-800 as well?  I'm curious to know what host DSP they used - is it one of the ADI SHARC processors?

[Elantric]

They use their standard ESOL eMCOS  pSOC

https://www-esol-co-jp.translate.goog/news/?_x_tr_sl=ja&_x_tr_tl=en&_x_tr_hl=en

https://www.vguitarforums.com/smf/index.php?topic=22744.0

[gumtownadmin]

This is what I was looking for in the past.
With the GK now serial data, it wouldn't take much to add a wireless radio unit and battery, as a trs plugin.

[GuitarBuilder]

This is what I was looking for in the past.
With the GK now serial data, it wouldn't take much to add a wireless radio unit and battery, as a trs plugin.

I suspect you'd have trouble sending power to the GK-5 via wireless.  Or were you referring to wireless for the regular guitar pickups?

[GuitarBuilder]

Another question to be confirmed: are there any analog signals in the GM-800?  I suspect that the logical route (pun intended) is to directly process the incoming digital signals.

[GuitarBuilder]

The GM-800 does not appear to take advantage of the bidirectional nature of A2B - in principle it could send 32 channels of analog and control/MIDI data back to the guitar!

One application that immediately comes to mind is hexaphonic sustain: instead of cramming the DSP pitch detection into the guitar it may be possible to send the appropriate signals to the sustain drivers from the floor box.  The extremely low latency (50 microseconds) makes it possible.

Other options could include effects with presets for the standard pickups.

[Elantric]

Remember todays GK-5 SERIAL GK Pickup is simply a mag divided pickup feeding three  TI OPA1677 Dual op amps into an  FPGA under the sticker performs the 6 channels of A/D to a 6 channel  TDM serial data stream compatible with the Analog Devices AD2428 A²B Tranceiver which is in transmit mode and acting as Power supply from the voltage on the TRS 100ohm twisted pair + drain shield (SERIAL GK) data transport layer..  Nothing more - zero DSP processing , zero guitar to MIDI at GK-5 - all that occurs inside the GM-800.

https://audioxpress.com/article/r-d-stories-getting-started-with-automotive-audio-bus-part1

Automotive Audio Bus (A2B®) Development Tools
Analog Devices Automotive Audio Bus (A2B®) System consists of a single master (GM-800) and at least one slave (GK-5), where the transceiver at the host controller is the master. The master transceiver (GM-800) generates clock, synchronization, and framing for all slave nodes and is programmable over a control bus (I2C) for configuration and readback. An extension of this control bus is embedded in the A2B data stream, which enables the host to directly access slave transceiver registers and any I2C-connected peripherals on slave nodes. Transceivers can connect directly to PDM microphones and numerous peripherals via I2C and a multichannel I2S/TDM interface. The transceiver also supports an A2B bus powering feature, where the master node (GM-800) supplies voltage and current to the slave nodes over the same daisy-chained, twisted-pair wire cable as used for the communication link. This eliminates the need for power supply on bus-powered slave nodes. Due to the numerous configurations that are possible for a given A2B system, several evaluation platforms can be used in combination to verify system operation.

[gumtownadmin]

I suspect you'd have trouble sending power to the GK-5 via wireless.  Or were you referring to wireless for the regular guitar pickups?

That is why I mentioned "battery" too. 

[GuitarBuilder]

That is why I mentioned "battery" too. 

You do need 50Mbps, that's not ordinary guitar wireless.....

[gumtown]

You do need 50Mbps, that's not ordinary guitar wireless.....

That's right,
 but there are enough 'off the shelf' chips available for low power/high bandwidth data transceivers to develop a wireless system,
 an since already digital in and out at both ends, the part count will be a lot less without the need to deal with A/D and D/A converters.
So if a wireless system were to materialize, it would be quite compact for a GK-5 system to plug into.

[gumtown]

Someone asked a question on another site about making a DIY GK Serial patch cable, apart from requiring a twin twisted & foil shielded cable (like Beldon),
 what are the connections for the TRS plugs ?,
 I would assume they are 1:1 through (tip to tip, ring to ring, shield to shield), is that correct ?
 

[Elantric]

1:1
T=T
R=R
S=S

Use AES/EBU Cable