Fast Single Phase LCD Energy Meter Design


The AS8218/AS8228 development kit includes a fully functional single-phase, two-current input energy meter platform. Two optically isolated serial interfaces are provided on-board, which allow programming of the on-chip 8051 micro-controller and configuration of all programmable features.

A USB interface, which is connected to UART1 of the IC, allows direct connection to a personal computer via a standard cable. User-friendly PC interface software provides immediate access to all registers and memory locations. Demonstration programmes of varying complexity are included with the development kit.

An RS232 interface connects to UART2 of the IC through two of the multipurpose inputs/outputs. When UART2 is connected to the PC, via the RS232 interface, program debugging can be performed. A monitor program is provided to enable this procedure.


The AS8218/AS8228 ICs have on-chip counters which can be used for automatic digital calibration during meter production. A calibration interface is provided for direct connection of an external reference meter. A current transformer and shunt resistor for mains current sensing are mounted on board for measurement of both live and neutral currents. Alternatively, simulated mains currents can be applied by inserting an analog interface board (AIB), eliminating the need for load currents during meter software development.

An AS8218/AS8228 application board is also available, which resembles a production meter design, having a minimum of external components. The AS8218/AS8228 application board measures energy to better than 0.1% accuracy over a 1000:1 dynamic range and far surpasses all the specification requirements of IEC and ANSI standards.