Timestamp Status | Option Timestamp |
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TS_MODE_STARTRESET
11
Must be written to enable the StartReset timestamp mode. The counter is reset on each start of the board. The times- tamps values are relative to the board start.
RefClock mode (optional)
The counter is split in a HIGH and a LOW part and an additional seconds signal, that affects both parts of the counter (TTL pulse with f = 1 Hz) must be fed in externally.
The HIGH part counts the seconds that have elapsed since the last counter reset with the reset command TS_RESET. The LOW part is reset to zero on every seconds signal and is clocked with the actual sample rate. The edge of the external secondssignal must be set seperately as described below.
This mode allows the recording of an absolute time of a trigger event. This even allows the synchronization of data that has been recorded with different boards.
Register | Value | Direction | Description | |
SPC_TIMESTAMP_CMD | 47000 | w | Writes a command to the timestamp command register. | |
SPC_TIMESTAMP_CMD | 47000 | r | Reads out the actual timestamp mode. | |
| TS_RESET | 0 | Resets the whole counter of the timestamp module to zero. Waits for synchronization to an external seconds signal. | |
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| This may last up to 1 second. The lower part of the counter can be reset with the external fed in second signal. The | |
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| edge of the reset signal can be programmed with the SPC_TIMESTAMP_RESETMODE register as shown in the table | |
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| below. |
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| TS_MODE_DISABLE | 10 | Disables the timestamp module. No timestamps are recorded. | |
| TS_MODE_REFCLOCK | 13 | Must be written to enable the RefClock timestamp mode. The counter must be manually reset by writing the command | |
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| TS_RESET to the command register. The counter is splitted into two parts. The upper part counts the seconds of an | |
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| external reference clock. The lower part is reset on each second signal and counts the samples. | |
The edge of the external TTL seconds signal can be programmed by the following register either to detect the rising or falling edge.
Register | Value | Direction | Description | |
SPC_TIMESTAMP_RESETMODE | 47050 | r/w | Defines the active edge of the external fed in seconds signal to reset the lower part of the counter. The | |
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| values written here do not affect the timestamp command TS_RESET. |
| TS_RESET_POS | 10 | The lower part of the counter will be reset on every rising edge of the external reset signal (seconds signal). | |
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| TS_RESET_NEG | 20 | The lower part of the counter will be reset on every falling edge of the external reset signal (seconds signal). | |
To get recordings in relation to each other it is importent to know the absolute start time. This time can be easily read out by the following register. The time is given back in seconds since midnight (00:00:00), January 1, 1970, which is the standard ’time_t’ in C/C++.
Register | Value | Direction | Description |
SPC_TIMESTAMP_STARTTIME | 47030 | r | Reads out the start time of the RefClock mode. Return value is the number of seconds since midnight |
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| (00:00:00), January 1, 1970, which is the standard ’time_t’ in C/C++. |
Timestamp Status
The timestamp module has its own status register for the timestamp FIFO. You can easily read out the FIFO status with the help of the timestamp status register shown in the table below.
Register | Value | Direction | Description | |
SPC_TIMESTAMP_STATUS | 47010 | r | Reads the status of the timestamp FIFO. | |
| TS_FIFO_EMPTY | 0 | The timestamp FIFO is still empty. | |
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| TS_FIFO_LESSHALF | 1 | There are values in the timestamp FIFO but less than half of the FIFO is filled. | |
| TS_FIFO_MOREHALF | 2 | More than half of the FIFO is filled with timestamps. | |
| TS_FIFO_OVERFLOW | 3 | The timestamp FIFO is full and possibly data has been lost. | |
Reading out timestamp data
Functions for accessing the data
There are two possibilities to access the timestamps that have been stored in the timestamp FIFO.
Reading out a single timestamp
You can read out one 32 bit value from the timestamp FIFO by using the register shown in the table below.
Register | Value | Direction | Description |
SPC_TIMESTAMP_FIFO | 47040 | r | Get one 32 bit value from the timestamp FIFO. If the FIFO is empty a zero will be returned. |
Because accessing the timestamp with this function will be done with single accesses, getting the value(s) this way is much slower than using the SpcGetData function as described below.
84 | MC.31xx Manual |