71M6533 Datasheet, PDF(64/124 Page) Teridian Semiconductor Corporation

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71M6533 Datasheet, PDF (64/124 Pages) Teridian Semiconductor Corporation – Energy Meter IC

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71M6533/71M6534 Data Sheet

FDS_6533_6534_004

readies the timer to start when the processor writes to the SLEEP or LCD_ONLY registers. The timer is

reset and disarmed whenever the processor is awake. Thus, if it is desired to wake the MPU periodically

(every 5 seconds, for example) the timer must be rearmed every time the part returns from SLEEP or

LCD mode.

2.6 Data Flow

The data flow between the Compute Engine (CE) and the MPU is shown in Figure 28. In a typical appli-

cation, the 32-bit CE sequentially processes the samples from the voltage inputs on pins IA, VA, IB, and

VB, performing calculations to measure 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. Figure 28 illustrates the CE/MPU data flow.

Pulses

Samples

Pre-

Processor

IRQ

Data

MPU

Post -

Processor

Processed

Metering

Data

I/O RAM (Configuration RAM)

Figure 28: MPU/CE Data Flow

2.7 CE/MPU Communication

Figure 29 shows the functional relationships between the CE and the MPU. The CE is controlled by the

MPU via shared registers in the I/O RAM and in RAM.

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 pro-

cessing data. This signal will occur once every multiplexer cycle. XFER_BUSY indicates that the CE is

updating data to the output region of the RAM. This will occur whenever the CE has finished generating a

sum by completing an accumulation interval determined by SUM_CYCLES * PRE_SAMPS samples. Inter-

rupts to the MPU occur on the falling edges of the XFER_BUSY and CE_BUSY signals.

Refer to Section 4.3 CE Interface Description for additional information on setting up the device using the

MPU firmware.

VAR

PULSES

(DIO7)

W (DIO6)

ADC

Mux Control

SAMPLES

APULSEW

APULSER

EXT PULSE

SAG CONTROL

DATA

CE BUSY

XFER BUSY

INTERRUPTS

MPU

DISPLAY (Memory

mapped LCD

segments)

SERIAL

(UART0/1)

EEPROM

(I2C)

DIO

I/O RAM (Configuration RAM)

Figure 29: MPU/CE Communication

v1.1

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