Maxim Integrated 71M6521BE Energy Meter IC Family Software - Manual (Page 54)

71M652X Software User’s Guide
Revision 1.7 TERIDIAN Proprietary 54 of 138
© Copyright 2005-2007 TERIDIAN Semiconductor Corporation
XFER_busy_rtc_int()
Clear IE_XFER
IE_XFER?
END
alt mux cycle?
yes
yes
Configure for alt mux cycle
Not first CE pass?
Copy data from CE DRAM to
IRAM
Decrement ce_first_pass
yes
no
no
yes
yes
Apply creep threshold
ce_first_pass = 0?
Enable pulses
Reset XFER_BUSY watchdog
IE_RTC?
no
Clear IE_RTC
Accumulate pulse counts
Clock compensation
Watchdog reset
IE_RTC or IE_XFER?
yes
no
no
yes
Figure 5-9: XFER_BUSY/RTC ISR
The interrupt service routine includes a loop. Without this loop, there is the chance of a rare, subtle timing error
because interrupt EXT6 is edge-triggered and the two interrupt sources "or" into it. The timing error will occur if the