Spectrum M2p.59 Series, Hardware Manual, Page: 83 / 190

Acquisition modes Commands
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size can be 2k as a minimum. If you need to work with ABA or timestamp data in smaller chunks please use the
polling mode as described later.
The pvDataBuffer must point to an allocated data buffer for the transfer. Please be sure to have at least the amount of memory allocated that
you program to be transferred. If the transfer is going from card to PC this data is overwritten with the current content of the card on-board
memory.
The pvDataBuffer needs to be aligned to a page size (4096 bytes). Please use appropriate software com -
mands when allocating the data buffer. Using a non-aligned buffer may result in data corruption.
When not doing FIFO mode one can also use the qwBrdOffs parameter. This parameter defines the starting position for the data transfer as
byte value in relation to the beginning of the card memory. Using this parameter allows it to split up data transfer in smaller chunks if one
has acquired a very large on-board memory.
The qwTransferLen parameter defines the number of bytes that has to be transferred with this buffer. Please be sure that the allocated memory
has at least the size that is defined in this parameter. In standard mode this parameter cannot be larger than the amount of data defined with
memory size.
Memory test mode
In some cases it might be of interest to transfer data in the opposite direction. Therefore a special memory test mode is available which allows
random read and write access of the complete on-board memory. While memory test mode is activated no normal card commands are pro -
cessed:
Invalidation of the transfer buffer
The command can be used to invalidate an already defined buffer if the buffer is about to be deleted by user. This function is automatically
called if a new buffer is defined or if the transfer of a buffer has completed
The dwBufType parameter need to be the same parameter for which the buffer has been defined:
Commands and Status information for data transfer buffers.
As explained above the data transfer is performed with the same command and status registers like the card control. It is possible to send
commands for card control and data transfer at the same time as shown in the examples further below.
The data transfer can generate one of the following status information:
Register Value Direction Description
SPC_MEMTEST 200700 read/write Writing a 1 activates the memory test mode, no commands are then processed.
Writing a 0 deactivates the memory test mode again.
uint32 _stdcall spcm_dwInvalidateBuf ( // invalidate the transfer buffer
drv_handle hDevice, // handle to an already opened device
uint32 dwBufType); // type of the buffer to invalidate as listed above under SPCM_BUF_XXXX
SPCM_BUF_DATA 1000 Buffer is used for transfer of standard sample data
SPCM_BUF_ABA 2000 Buffer is used to read out slow ABA data. Details on this mode are described in the chapter about the ABA mode
option. The ABA mode is only available on analog acquisition cards.
SPCM_BUF_TIMESTAMP 3000 Buffer is used to read out timestamp information. Details on this mode are described in the chapter about the times -
tamp option. The timestamp mode is only available on analog or digital acquisition cards.
Table 37: Spectrum API: Command register and commands for DMA transfers
Register Value Direction Description
SPC_M2CMD 100 write only Executes a command for the card or data transfer
M2CMD_DATA_STARTDMA 10000h Starts the DMA transfer for an already defined buffer. In acquisition mode it may be that the card hasn’t received a
trigger yet, in that case the transfer start is delayed until the card receives the trigger event
M2CMD_DATA_WAITDMA 20000h Waits until the data transfer has ended or until at least the amount of bytes defined by notify size are available. This
wait function also takes the timeout parameter described above into account.
M2CMD_DATA_STOPDMA 40000h Stops a running DMA transfer. Data is invalid afterwards.
Table 38: Spectrum API: status register and status codes for DMA data transfer
Register Value Direction Description
SPC_M2STATUS 110 read only Reads out the current status information
M2STAT_DATA_BLOCKREADY 100h The next data block as defined in the notify size is available. It is at least the amount of data available but it also can
be more data.
M2STAT_DATA_END 200h The data transfer has completed. This status information will only occur if the notify size is set to zero.
M2STAT_DATA_OVERRUN 400h The data transfer had on overrun (acquisition) or underrun (replay) while doing FIFO transfer.
M2STAT_DATA_ERROR 800h An internal error occurred while doing data transfer.