Datasheet
71M6543F/71M6543G Data Sheet
v2 117
5.3.4 Environment
Before starting the CE using the CE_E bit (I/O RAM 0x2106[0]), the MPU has to establish the proper
environment for the CE by implementing the following steps:
• Locate the CE code in Flash memory using CE_LCTN[5:0] (I/O RAM 0x2109[5:0]) in the 71M6543F
and CE_LCTN[6:0] (I/O RAM 0x2109[6:0]) in the 71M6543G.
• Load the CE data into RAM.
• Establish the equation to be applied in EQU[2:0] (I/O RAM 0x2106[7:5]).
• Establish the accumulation period and number of samples in SUM_SAMPS[12:0] (I/O RAM
0x2107[4:0], 0x2108[7:0]).
• Establish the number of cycles per ADC multiplexer frame (MUX_DIV[3:0] (I/O RAM 0x2100[7:4])).
• Apply proper values to MUXn_SEL, as well as proper selections for DIFFn_E (I/O RAM 0x210C[ ]) and
RMTn_E (I/O RAM 0x2709[ ] in order to configure the analog inputs.
• Initialize any MPU interrupts, such as CE_BUSY, XFER_BUSY, or the power-failure detection interrupt.
When different CE codes are used, a different set of environment parameters need to be established.
The exact values for these parameters are listed in the Application Notes and other documentation which
accompanies the CE code.
Operating CE codes with environment parameters deviating from the values specified by Maxim
leads to unpredictable results.
Typically, there are fifteen 32768 Hz cycles per ADC multiplexer frame (see 2.2.2). This means that the
product of the number of cycles per frame and the number of conversions per frame must be 14 (allowing
for one settling cycle). The default configuration is FIR_LEN = 01, I/O RAM 0x210C[1] (two cycles per
conversion) and MUX_DIV[3:0] = 7 (7 conversions per multiplexer cycle).
Sample configurations can be copied from Demo Code provided by Maxim with the Demo Kits.
5.3.5 CE Calculations
Referring to Table 71, The MPU selects the desired equation by writing the EQU[2:0] (I/O RAM
0x2106[7:5]).
Table 71: CE EQU[2:0] Equations and Element Input Mapping
EQU
[2:0]*
Watt & VAR Formula
(WSUM/VARSUM)
W0SUM/
VAR0SUM
W1SUM/
VAR1SUM
W2SUM/
VAR2SUM
I0SQ
SUM
I1SQ
SUM
I2SQ
SUM
2
VA*IA + VB*IB
(2-element, 3-W, 3φ Delta)
VA * IA VB * IB N/A IA IB –
3
VA*(IA-IB)/2 + VC*IC
(2 element, 4W 3φ Delta)
VA*(IA-IB)/2 – VC*IC IA-IB IB IC
4
VA*(IA-IB)/2 + VB*(IC-IB)/2
(2 element, 4W 3φ Wye)
VA*(IA-IB)/2 VB*(IC-IB)/2 – IA-IB IC-IB IC
5
VA*IA + VB*IB + VC*IC
(3 element, 4W 3φ Wye)
VA*IA VB*IB VC*IC IA IB IC
Note:
* Only EQU[2:0] = 5 is supported by the currently available CE code versions for the 71M6543. Contact
your local Maxim representative for CE codes that support equations 2, 3 and 4.