71M6543F/H and 71M6543G/GH Data Sheet
active power (Wh), reactive power (VARh), A2h, and V2h for four-quadrant metering. These measurements
are then accessed by the MPU, processed further and output using the peripheral devices available to the
MPU.
Both the CE and multiplexer are controlled by the MPU via shared registers in the I/O RAM and in RAM.
The CE outputs a total of six discrete signals to the MPU. These consist of four pulses and two interrupts:
•
•
•
•
CE_BUSY
XFER_BUSY
WPULSE, VPULSE (pulses for active and reactive energy)
XPULSE, YPULSE (auxiliary pulses)
These interrupts are connected to the MPU interrupt service inputs as external interrupts. CE_BUSY
indicates that the CE is actively processing data. This signal occurs once every multiplexer cycle (typically
396 µs), and indicates that the CE has updated status information in its CESTATUS register (CE RAM 0x80).
XFER_BUSY indicates that the CE is updating data to the output region of the RAM. This update occurs
whenever the CE has finished generating a sum by completing an accumulation interval determined by
SUM_SAMPS[12:0], I/O RAM 0x2107[4:0], 2108[7:0], (typically every 1000 ms). Interrupts to the MPU occur
on the falling edges of the XFER_BUSY and CE_BUSY signals.
WPULSE and VPULSE are typically used to signal energy accumulation of real (Wh) and reactive (VARh)
energy. Tying WPULSE and VPULSE into the MPU interrupt system can support pulse counting.
XPULSE and YPULSE can be used to signal events such as sags and zero crossings of the mains voltage
to the MPU. Tying these outputs into the MPU interrupt system relieves the MPU from having to read the
CESTATUS register at every occurrence of the CE_BUSY interrupt in order to detect sag or zero crossing
events.
Refer to 5.4 CE Interface Description on page 120 for additional information on setting up the device
using the MPU firmware.
Pulses
XPULSE
YPULSE
Interrupts
VPULSE
CE
Processed
Metering
Data
WPULSE
CE_BUSY
XFER_BUSY
Samples
CESTATUS
CECONFIG
MPU
Control
MUX
XRAM
I/O RAM (Configuration RAM)
Figure 26: MPU/CE Data Flow
v1.2
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