Option Gated Replay | Output modes |
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Option Gated Replay
The option Gated Replay allows the data generation controlled by an external gate signal. Data will only be output, if the programmed gate condition is true.
Output modes
Standard Mode
Data will be replayed as long as the gate signal fulfills the gate condition that has had to be programmed before. At the end of the gate interval the replay will be stopped and the board will pause until another gates condition is detected. If the total amount of data to replay has been reached the board stops im- mediately (see figure). The total amount of samples to be replay- ed can be defined by the memsize register.
The table below shows the register for enabling Gated Replay. For detailed information on how to setup and start the standard generation mode please refer to the relevant chapter earlier in this manual.
Register
SPC_GATE
SPC_MEMSIZE
Value | Direction | Description |
220400 | r/w | Enables Gated Replay mode. |
10000 | r/w | Defines the total amount of samples to replay. |
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FIFO Mode
The Gated Replay in FIFO Mode is similar to the Gated Replay in Standard Mode. In contrast to the Standard mode you cannot program a certain total amount of samples to be replayed. The generation is running until the user stops it. The data is transfered to the board FIFO block by FIFO block by the driver. These blocks can be online generated by the user program.
The advantage of Gated Replay in FIFO mode is that you can stream data online from the host system to the board, so you can replay a huge amount of data from the hard disk with a lower average data rate than in conventional FIFO mode. The table be- low shows the dedicated register for enabling Gated Replay. For
detailed information how to setup and start the board in FIFO mode please refer to the according chapter earlier in this manual.
Register
SPC_GATE
Value | Direction | Description |
220400 | r/w | Enables Gated Replay mode. |
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Trigger modes
General information and trigger delay
Not all of the board’s trigger modes can be used in combi- nation with Gated Replay. All possible trigger modes are li- sted below. Depending on the different trigger modes, the chosen sample rate, the used channels and activated board synchronization (see according chapter for details about synchronizing multiple boards) there are different delay times between the trigger event and the first replayed sam- ple(see figure). This start delay is necessary as the board is equipped with dynamic RAM, which needs refresh cycles to keep the data in memory when the board is not replaying. It is fix for a certain board setup.
All possible start delays in samples between the trigger event and the first replayed sample are listed in the table below.
(c) Spectrum GmbH | 63 |
