*********** 89S52 Project Board -1 ********

The 89S52 project board was designed for easy microcontroller project development. The board has two channel 12-bit ADC, 4-digit seven segment LED , text LCD connector, four tact switches, and the ISP loader.

The hardware block diagram is shown in Fig. 2. The MCU is 89S52, 8kB flash microcontroller.

Download :

Schematic and BOM	schematic.pdf
C source code	thermistor.c
Orcad Schematic File	N/A
Intel-Hex file	thermo.hex

Simple Power Meter

The project shows how to use an analog AC clamp meter and the 89S52 project board for displaying active power in Watt unit. The 89S52 project board has a 12-bit ADC with 0 to +5VDC input. The AC clamp meter provides output current 100uA per 30A. We can use LM324 opamp to convert input current to voltage. The program computes active power by simply multiplying the RMS voltage to the RMS current. My plan is to hook the circuit to the load center of my house and to provide remote display with RS422.

Block diagram of a simple power meter.

The current-to-voltage converter using LM324 provides short circuit input for the current source. The 50k resistance gives +5V output for 100uA input. C1 is added to filter 100Hz ripple from AC clamp meter.

Download:

C source code	power.c
Intel-Hex file	power.hex