71m6521be Maxim Integrated Products, Inc., 71m6521be Datasheet - Page 58

• Manufacturer Part Number: 71m6521be
• Description: Energy Meter Ic
• Manufacturer: Maxim Integrated Products, Inc.

The data flow between CE and MPU is shown in Figure 26. In a typical application, the 32-bit compute engine (CE) sequen-
tially processes the samples from the voltage inputs on pins IA, VA, IB, and VB, performing calculations to measure active
power (Wh). These measurements are then accessed by the MPU, processed further and output using the peripheral devices
available to the MPU.
Figure 27 shows the functional relationship between CE and MPU. The CE is controlled by the MPU via shared registers in the
I/O RAM and by registers in the CE DRAM. The CE outputs two interrupt signals to the MPU: CE_BUSY and XFER_BUSY,
which are connected to the MPU interrupt service inputs as external interrupts. CE_BUSY indicates that the CE is actively
processing data. This signal will occur once every multiplexer cycle. XFER_BUSY indicates that the CE is updating data to the
output region of the CE DRAM. This will occur whenever the CE has finished generating a sum by completing an accumulation
interval determined by SUM_CYCLES * PRE_SAMPS samples. Interrupts to the MPU occur on the falling edges of the
XFER_BUSY and CE_BUSY signals.
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Mux Ctrl.
ADC
Samples
I/O RAM (CONFIGURATION RAM)
SAMPLES
© 2005-2008 TERIDIAN Semiconductor Corporation
Processor
Pulse
CE
Figure 27: MPU/CE Communication
I/O RAM (Configuration RAM)
CE
Pre-
CE/MPU Communication
Figure 26: MPU/CE Data Flow
WPULSE
(DIO6)
Data Flow
IRQ
Data
INTERRUPTS
SAG CONTROL
XFER_BUSY
CE_BUSY
DATA
Processor
MPU
Post-
MPU
Processed
Energy Meter IC
Metering
Data
LCD segments)
DISPLAY (me-
mory-mapped
(UART0/1)
EEPROM
DIO
SERIAL
(I2C)
71M6521BE
DATA SHEET
JANUARY 2008
V1.0