1. 	Overview

The new version of the DIGI96/8 PRO with a dark blue PCB design is in most items identical to the earlier DIGI96/8 PRO. That's why this addendum lists only differences and additions. For all basic information please read Internal Reference DIGI96 Series.

Differences in hardware:

The analog output in Revision 2 uses an AD1855 as DA-converter, offering a much higher performance as the original AK4321. The data format and control did not change. Please note that this chip no longer supports De-Emphasis in double speed mode (the earlier AKM allowed to activate De-Emphasis regardless of the frequency, although the filter did not scale correctly). Revision 4 uses the AD1852, which again has much better THD+N values and a different volume control range (14 bit instead of 12 bit. In case the volume control is supported different routines for both cards have to be implemented). As the analog output causes a loud pop/click at power on/off, which is very annoying when using active monitors, a Speaker Protection circuit was added (dac_en bit). Instead of a relais latest electronic switches are used (DG411).

Due to the fact that some companies implement badly designed ADAT inputs into their devices an option 'Boot ADAT' was added (Jumper J4). This jumper defines the startup-format from power-on until the driver is loaded, and can be set to ADAT or SPDIF.

When ADAT is the active output format the coaxial and XLR-outputs are switched off. This avoids noise and errors at other SPDIF-based devices which are attached to these outputs.

The card no longer uses the Crystal SPDIF receiver. This circuit is now included in the FPGA (now a XCS30XL) and uses the ADAT Bitclock-PLL to properly receive and decode the biphase signal. No changes in the driver are required.

The XCS30 XL allowed to add some more modes and features. These also require no change in the driver, as they are automatically activated when setting the 'Input' mode (monitoring), thus giving a monitoring capability where the old hardware muted automatically (no bypass).

- Sample Buffer: This new technology allows a monitoring mode completely independent from the actual clock situation (master/slave) and signals (sample rate) at input and output.

- ADAT to SPDIF Converter: The sample buffer also allows monitoring in Mixed Mode (ADAT in, SPDIF out). This enables the PRO to be used as ADAT to SPDIF format converter. As the card does not include any mixer the user has to select, which of the ADAT stereo pairs is passed through to the SPDIF output. This is set by bits 28/29 (monitor..). In the settings dialog the user simply chooses the stereo pair for the analog output, choosing automatically the used stereo pair for this converter mode.

  
- SPDIF to ADAT Converter: In this case (SPDIF In, ADAT Out, activated by 'Force Adat') the hardware automatically copies the stereo input data to the other three stereo output pairs of the ADAT output.

2. Register

Write to the control register

Additional register (Offset 0x20004)

0	wsel	Clock Source for playback is an external clock signal (Word Clock In), when this bit is set. Not changed to earlier model.

New:

6	dac_en	("soft-mute-bit"):
0 = analog output muted (default)
1 = analog output active

When first time starting the driver this bit should be set permanently. Before doing this please reset the DAC using the already exisiting PD bit.

When un-loading the driver (shutdown of the system) this bit should be set back to 0, to mute the analog output, and to avoid a pop/click when the power supply's voltages break down.
	
7
8
9	CLATCH
CCLK
CDATA	These bits are connected to the corresponding pins of the D/A-converter. These bits can be used to access internal registers of the DAC. The format of this Microprocessor interface is described in the AD1855 and AD1852 datasheet (available at www.analog.com). These bits should remain on low level when not used!

3. Important note

When booting the computer the bits CLATCH, CCLK and CDATA are set to a random state. The DAC therefore is in an undefined state when the driver is loaded. Before setting dac_en the DAC has to be reset using PD!

5. Revision ID

The PCI revision ID in the configuration area (Offset 08h) contains a version number:

Digi96/8 PRO, first revision: 000

DIGI96/8 PRO, second revision: 002 (AD1855)

DIGI96/8 PRO, third revision: 004 (AD1852)

4. Example for a configuration dialog

The picture below shows the DIGI96/8 PRO settings dialog of the Windows 98/NT driver, which is basically identical for all cards of the DIGI96 series.

Function block Analog Output

Two sliders providing a nearly stepless analog volume control were added to the Windows driver. The control range is 0 to -60 dB. The precise amount of attenuation is shown as numerical value below the sliders. The sliders can be adjusted simultaneously by activating 'Couple'.

The switches in 'Output Format' were newly arranged and simplified. A/S Conv. forces the card's output into SPDIF (stereo) operation, enabling the ADAT to SPDIF converter. The other way round was already implemented (Force ADAT).

The clock mode section is now identical on all cards.

End