Supervisory Terminal ST-99

A single board embedded computer for supervising multiple devices from a centralized location.

Contact: Ori Novanda (cargmax-at-gmail.com)

I designed and built this embedded system back in 1997-1999. I developed it for supervising multiple devices (from different vendors) from a central location. The system used the Intel 8052 microcontroller as the main controller. I designed the PCB in two layers. I developed the firmware fully in assembly (MCS-51/52) and provided some hardware functionality through emulator firmware (e.g. custom alarm sound, I2C bus, and secondary serial port) to save the bill of materials (BOM).

Features:

• Addressable I/O ports (expansion bus): to monitor up to 8-bit x 256 devices
• Addressable slave serial ports (expansion bus): up to 256 RS-232 serial ports
• Master serial port to communicate to a PC
• Printer port to log events through an external printer
• On-board Real Time Clock and Watchdog circuitry
• Build-in LCD and keypad
• Alarm sound

Schematics:

CPU

Parallel Expansion Board

Serial Expansion Board

PCBs:

Main Board

Main Board Component Layout:

Keypad Board

Parallel Expansion Board

Serial Expansion Board