Virtex-6 FPGA System Monitor
35
UG370 (v1.1) June 14, 2010
System Monitor Timing
Conversion Phase
The conversion phase starts on the sampling edge (next rising edge of DCLK) at the end of
the acquisition phase. The BUSY signal transitions to an active High on the next rising edge
of DCLK to indicate the ADC is carrying out a conversion. The conversion phase is 22
ADCCLK cycles. The conversion result transfers to the status registers 10 DCLK cycles
after BUSY transitions Low, and the EOC logic output pulses High for one DCLK cycle. If
the channel being converted is also being filtered, then the filtered data is only transferred
to the status registers when the last sample result has been converted. Thus, if a channel is
being averaged, an EOC pulse is only generated for the last conversion result, such as the
16
th
, 64
th
, 256
th
sample (see
). When
averaging is enabled, write operations to the configuration registers will not be acted on
until EOC is pulsed, i.e., when the filtering operation is complete.
When System Monitor is being operated in sequence mode, the user identifies the channel
being converted by monitoring the channel address (CHANNEL[4:0]) logic outputs. The
multiplexer channel address of the channel being converted is updated on these logic
outputs when BUSY transitions Low at the end of the conversion phase. The channel
address outputs can be used with the EOC and DRDY signals to automatically latch the
contents of the output data registers into a FIFO or block RAM (see
). This is accomplished by connecting the CHANNEL[4:0] outputs to
DADDR[4:0] (with DADDR[6:5] = 0), using EOC as a DEN (enable) for the DRP, and using
DRDY as a WE (write enable) for the block RAM.
System Monitor’s EOS signal has the same timing as EOC. This signal is pulsed when the
output data register for the last channel in a programmed channel sequence is updated.
X-Ref Target - Figure 14
Figure 14:
Continuous Sampling Mode Timing
DCLK
1
104
1
9
18
12
19
2
3
4
10
6
12
7
13
26
31
5
11
25
30
1
2
3
4
32
24
23
29
ADCCLK
Acquisition cycles can be extended to 10 to allow more acquisition time
Acquisition Time
Acquisition Time
Conversion Time
BUSY
Nth Conversion Finished
Nth Sampling Edge
EOC / EOS
ALM[2:0] / OT
CHANNEL[4:0]
N-1 Channel Selection
N Selection
UG370_14_060809
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