Alesis Hammerfall DSP System manual Midi, Word Clock Input and Output

22.3 MIDI

The HDSP MADI offers two MIDI I/O via 5-pin DIN connectors. The MIDI ports are added to the system by the driver. Using MIDI capable software, these ports can be accessed under the name MADI MIDI. Using more than one HDSP MADI, a consecutive number is added to the port name, like MADI MIDI In 1 (2) etc.

The MIDI In port is available for both GSIF (GSIF-2 Low Latency) and standard MME MIDI si- multaneously.

The third MIDI port, MADI MIDI In 3 (1) and MADI MIDI Out 3 (1), receives and transmits MIDI data via MADI. This allows for a direct communication between systems with HDSP MADI cards. Additionally MIDI data can be transmitted from/to RME's ADI-648 and ADI-642. Also ADI- 648 and ADI-642 can be MIDI remote controlled without any additional line or cabling between computer (MADI card) and both units.

23. Word Clock

23.1 Word Clock Input and Output

SteadyClock guarantees an excellent performance in all clock modes. Based on the highly effi- cient jitter suppression, the HDSP MADI refreshes and cleans up any clock signal, and provides it as reference clock at the BNC output (see chapter 30.6).

Input

The HDSP MADI's transformer isolated word clock input is active when Pref. Sync Ref in the Settings dialog has been switched to Word Clock, the clock mode AutoSync has been acti- vated, and a valid word clock signal is present. The signal at the BNC input can be Single, Dou- ble or Quad Speed, the HDSP MADI automatically adapts to it. As soon as a valid signal is de- tected, the green LED is lit, and the Settings dialog shows either Lock or Sync (see chapter 30.2).

Thanks to RME's Signal Adaptation Circuit, the word clock input still works correctly even with heavily mis-shaped, dc-prone, too small or overshoot-prone signals. Thanks to automatic signal centering, 300 mV (0.3V) input level are sufficient in principle. An additional hysteresis reduces sensitivity to 1.0 V, so that over- and undershoots and high frequency disturbances don't cause a wrong trigger.

The word clock input is shipped as high impedance type (not terminated). A push switch allows to activate internal termination (75 Ohms). The switch is found beside the word clock input socket. Use a small pencil or similar and carefully push the blue switch so that it snaps into its lock position. The yellow LED will be lit when termination is active. Another push will release it again and de-activate the termination.

Output

The word clock output of the HDSP MADI is constantly active, providing the current sample frequency as word clock signal. As a result, in Master mode the provided word clock is defined by the currently used software or the DDS dialog. In Slave mode the provided frequency is iden- tical to the one present at the currently chosen clock input. When the current clock signal fails, the HDSP MADI switches to Master mode and adjusts itself to the next, best matching fre- quency (44.1 kHz, 48 kHz etc.).

Selecting 96 kHz – 48K Frame in the Settings dialog causes the output signal to always stay within the range of 32 kHz to 48 kHz. So at 96 kHz sample rate, the output word clock is 48 kHz.

User's Guide HDSP MADI © RME 39