ICP DAS USA PCI-D64HU, Руководство пользователя, Страница: 12 / 128

PCI-D64HU User’s Manual (Ver.1.0, Dec/2009)
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The input data will be saved into DI FIFO after a strobe is generated. When the DI
FIFO is not empty, the saved data will be automatically transferred to the main
memory of computer system by the bus mastering DMA controller.
1. Digital Input data is ready and an I_REQ signal is generated by external device.
2. Digital input data is saved to FIFO.
3. If the FIFO is not empty and PCI bus is not occupied, the data will be transferred
to main memory.
Handshaking Mode
The PCI-D64HU also supports handshaking data transfer mode. The data transfer
rate is controlled by REQ and ACK signals to guarantee no data loss.
The operation of DI Handshaking
Latch Digital
Input Data
I_REQ
( Input Signal )
Digital Input
FIFO
PC’s Main
Memory
Digital
Input Data
Bus mastering
DMA data Transfer
1
2
3
I_ACK
( Output Signal )
4
5
1. Digital Input data is ready.
2. An I_REQ signal is generated by external device.
3. Digital input data is saved to FIFO.
4. An I_ACK signal is generated and sent to the external device.
5. If the FIFO is not empty and PCI bus is not occupied, the data will be
transferred to main memory.
The operation of DO Handshaking