This paper introduces the main features and advantages of EM773, block diagram, schematic block diagram of smart meter, BOM of main components of electric meter and circuit diagram of electric meter wireless plug meter and meter.
NXP's EM773 is a low-power 32-bit smart meter IC based on ARM Cortex-M0 with CPU frequency up to 48MHz, rich peripherals including up to 32KB of flash memory, up to 8KB of data memory, and a Fast-mode PlusI2C bus interface. An RS-485/EIA-485 UART, an SPI interface with SSP features, three general purpose counters/timers, up to 25 GPIOs, and a measurement engine for energy measurement.
Key features and benefits of EM773:
System:
ARM Cortex-M0 processor, running at frequencies of up to 48 MHz.
ARM Cortex-M0 built-in Nested Vectored Interrupt Controller (NVIC).
Serial Wire Debug.
System TIck TImer.
Memory:
32 kB on-chip flash programming memory.
8 kB SRAM.
In-System Programming (ISP) and In-ApplicaTIon Programming (IAP) via on-chip bootloader software.
Digital peripherals:
Up to 25 General Purpose I/O (GPIO) pins with configurable pull-up/pull-down resistors.
GPIO pins can be used as edge and level sensiTIve interrupt sources.
High-current output driver (20 mA) on one pin.
High-current sink drivers (20 mA) on two I2C-bus pins in Fast-mode Plus.
Three general purpose counter/timers with a total of two capture inputs and 10 match outputs.
Programmable WatchDog Timer (WDT).
Analog peripherals:
Metrology Engine for Smart Metering with two current inputs and a voltage input.
Serial interfaces:
UART with fractional baud rate generation, internal FIFO, and RS-485 support.
One SPI controller with SSP features and with FIFO and multi-protocol capabilities.
I2C-bus interface supporting full I2C-bus specification and Fast-mode Plus with a data rate of 1 Mbit/s with multiple address recognition and monitor mode.
Clock generation:
12 MHz internal RC oscillator trimmed to 1 % accuracy that can optional be used as a system clock.
Crystal oscillator with an operating range of 1 MHz to 25 MHz.
Programmable watchdog oscillator with a frequency range of 7.8 kHz to 1.8 MHz.
PLL allows CPU operation up to the maximum CPU rate without the need for a high-frequency crystal. May be run from the system oscillator or the internal RC oscillator.
Clock output function with divider that can reflect the system oscillator clock, IRC clock, CPU clock, and the Watchdog clock.
Power control:
Integrated PMU (Power Management Unit) to minimize power consumption during Sleep, Deep-sleep, and Deep power-down modes.
Three reduced power modes: Sleep, Deep-sleep, and Deep power-down.
Processor wake-up from Deep-sleep mode via a dedicated start logic using up to 13 of the functional pins.
Power-On Reset (POR).
Brownout detect with four separate thresholds for interrupt and forced reset.
Unique device serial number for identification.
Single 3.3 V power supply (1.8 V to 3.6 V).
Available as 33-pin HVQFN package.
EM773 application:
Smart Metering 
figure 1. EM773 block diagram 
figure 2. EM773 smart meter principle block diagram 
image 3. EM773 CGU block diagram 
Figure 4. EM773 electric meter main component BOM 
Figure 5. EM773 plug type meter outline drawing 
Figure 6. EM773 smart meter wireless plug meter circuit diagram wireless plug meter indicator: 
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