71M6543F/H and 71M6543G/GH Data Sheet
VB
IB
VA
61.04 µs
1
IC
VC
IA
ID
30.5 µs
61.04 µs
61.04 µs
61.04 µs
Multiplexer Frame (15 x 30.518 µs = 457.8 µs)
MUX_DIV = 7 Conversions
Settle
S
CK32
(32768 Hz)
MUX
STATE
S
0
2
3
4
5
6
Figure 10: Samples from Multiplexer Cycle (Frame)
The end of each multiplexer cycle is signaled to the MPU by the CE_BUSY interrupt. At the end of each
multiplexer cycle, status information, such as sag data and the digitized input signal, is available to the MPU.
833ms
20ms
XFER_BUSY
Interrupt to MPU
Figure 11: Accumulation Interval
Figure 11 shows the accumulation interval resulting from SUM_SAMPS[12:0] = 1819 (I/O RAM 0x2107[4:0]
and 0x2108[7:0]), consisting of 1819 samples of 457.8 µs each, followed by the XFER_BUSY interrupt.
The sampling in this example is applied to a 50 Hz signal. There is no correlation between the line signal
frequency and the choice of SUM_SAMPS[12:0]. Furthermore, sampling does not have to start when the
line voltage crosses the zero line, and the length of the accumulation interval need not be an integer
multiple of the signal cycles.
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