Operation Theory
41
4.7
Clocking Mode
The data input to or output from the FIFO is operated in a specific
rate. The specific sampling rate or the pacer rate can be program-
mable by software, by external clock, or by easy handshaking pro-
tocol.
Four clocking modes are provided in the cPCI/PCI/PCIe-7300A to
sample input data to the FIFO or output date from FIFO to the
external devices. They are:
1.
Internal Clock
: Three sources are available to activate
both digital input and digital output. They are 20 MHz,
10MHz, and programmable timer 82C54. There are
three counters in 82C54, counter 0 is used to generate
sampling clock for digital input, counter 1 is used timer
pacer for digital output, and counter 2 is used for inter-
rupt function. The configuration is illustrated as follows.
Figure 4-6: Timer configuration
2.
External Clock
: This mode is only applied for digital
input. The digital inputs are handled by the external clock
strobe (DI-REQ). The DI-ACK signal reflects the almost
full status of the input FIFO. The DI-ACK is asserted
when input FIFO is not almost full, which means the
external device can input data. If the input FIFO is
almost full, the DI-ACK is de-asserted, then the external
device should pause data transfer and wait for the asser-
Содержание cPCI-7300A
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Страница 10: ...vi List of Figures...
Страница 18: ...8 Introduction...
Страница 21: ...Installation 11 2 4 cPCI PCI PCIe 7300A Layout Figure 2 1 PCI 7300A Layout Diagram...
Страница 22: ...12 Installation Figure 2 2 cPCI 7300A Layout Diagram Figure 2 3 PCIe 7300A Layout Diagram 167 65 111 15...
Страница 26: ...16 Installation Figure 2 4 CN1 Pin Assignment...
Страница 100: ...90 C C Libraries BufNotDWordAlign DMADscrBadAlign...
Страница 108: ...98 C C Libraries...
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