XVA1 – RC8

This build has no changes on the sound engine, but it introduces a few new things on the interfaces.

USB and External UART

The USB communication is no longer sustained at 500 Kbps, and XLoad isn’t using the Win32 API anymore.

Starting on this build, the USB communication happens at 12 Mbps (USB2 full-speed mode). Almost any USB2 port will work well in this new mode.

The communication uses a rather esoteric mode in the FTDI chip in the CMOD-A7, the FT2232H, which achieves greater speeds solidly (and avoids the need to specify the COM port in XLoad).

This extra speed has only a marginal gain on the standard bank/program loading operations, mostly because they are limited by EEPROM or flash memory erase/write speeds.

However, it allows for XVA1 audio to be digitally sent thru the USB port. XLoad now has a ‘recording mode’ (activated with ‘. <filename>’ in the new terminal mode), which will create a 96kHz 24-bit stereo audio file, containing XVA1 audio performance.

This needed also a derivative work: as most MCU won’t be able to open a 12 Mbps UART, the external UART is still at 500 Kbps. Previously, both UARTs (USB and external) were simply OR’ed together. Now they are separate, so XVA1 can receive external SetParam and GetParam commands, while sending audio to the USB.

Also, this build has the updated XVA1_Parameters Excel sheet, ready for 12 Mbps.

LEDs

The red in the multicolor LED in the CMOD (set to indicate audio post-fx clipping) was somehow lost when the audio and midi activity were on.

In RC8 I hacked the yellow PROG_DONE board LED to be the clipping indicator. This has the good side effect of saving a few milliamps.

Also, one of the green side LEDs will now blink if XVA1 is streaming audio to USB.

XLoad

All the command-line commands (except for image loading, which requires the bitloader) were now moved to the new terminal mode.

Besides initializing/loading/saving programs and banks, setting and getting parameter values (automatically handling the parameters > 255), there are now commands to set/get the MIDI channel and program name.