Rita-51J is a low-cost Internetworkable controller board using Rigel's Internet Technology Architecture (RITA). 

Hardware Overview  
  • Uses any  8051 in the PLCC package
  • 128K of SRAM 
  • 128K 5-volt FLASH ROM
  • 1 full-duplex serial port on board (2 with the DS87C520 or DS89C420)
  • 12 general purpose digital input / output bits 
  • Demultiplexed processor Address and Data lines
  • All system signals are available on a 40-pin header
  • Prototyping area for additional circuitry
  • Shielded RJ-45 connector with LAN and LINK indicators
  • 5 volt regulator on board
  • Power supplied to the board by way of a 2 position terminal block
  • Power on LED
  • Operating temperature 0 to 70C, extended temp available
  • Machine screw sockets under all through-hole chips
  • 2 layer 3.5" x 5" board
  • Mounting holes in corners

The board may be populated with a wide range of high-speed 8051 microcontrollers in the 44-pin PLCC package. The board uses the CS8900A Ethernet driver to directly connect to a 10Base-T network through a shielded RJ-45 socket. The MCS-51 / CS8900A combination takes advantage of readily available hardware and software tools as well as the wealth of publicly available applications source code.

A new textbook from Rigel Press, "Networking Eight-Bit Microcontrollers, Fundamentals and Applications with the 8051" uses the Rita-51J board to explain the basics of using microcontrollers on the Internet.

Download the Rita-51J User's Manual

The Rita-51J has has circuitry to support two RS232 serial ports. All 8051 microcontrollers have at least one on-chip UART. Microcontrollers (e.g. DS87C520 or DS89C420) with two serial ports may use both channels. The board comes with 128K RAM and 128K 5-volt FLASH ROM. The Rita-51J uses a CPLD (complex programmable logic device) to implement a variety of memory schemes, including Rigel's RROS, RRM and the RIM architectures.

Rita-51's small size makes it suitable for OEM applications.  It contains large memory to facilitate embedded TCP/IP applications.  The on-board FLASH ROM may be programmed directly from Reads51. A stand-alone software utility to program is also available from our website.  Despite its high performance the RITA-51J is a low cost board with a prototyping area, 4 user's buttons and 4 LEDs, which makes it an ideal platform for students and hobbyists.

Developing applications so the Rita-51J can run on the Internet. 

  1. Write and debug the application program that will reside on the Rita-51J using Rigel Corporation’s development tool Reads51.  A royalty-free library of network drivers and utility support functions, NetApi51 is given to be used with Reads51 (see example).
    (Alternatively, you may use any public domain or third-party software development tools, and TCP/IP libraries. )
  2. Download your program the to Rita-51J FLASH using the Reads51 Software.
  3. Use the RitaBrowser  (example) to talk to your Rita-51J on the internet.

Software Overview
Reads51 is an integrated applications software development system, which runs on an IBM PC or compatible host. Reads51 allows writing, compiling, assembling, debugging, downloading, and running applications software in the MCS-51 language. Reads51 contains a C compiler, relative assembler, linker/locator, editor,  chip simulator, assembly language debugger, and host-to-board communications in a user-friendly, menu-driven environment.

RitaBrowser monitors and controls Internet appliances built with Rigel Corporation's RITA family of control boards.  The RITA nodes may be on the Internet or on a private network such as a personal network or a company intranet. 

Documentation for our products includes a review of the software and hardware, sample programs.  All of our documentation (except circuit diagrams) is available on the web. 

A well-regulated 5-volt (±5% @500mA) power supply, a serial cable, and a RJ45 cable are to be provided by the user.

We offer three standard options.  The Rita-51J with a generic 87C52 / 89C52 operating at 24MHz, with either the DS89C420 or DS87C520 operating at 33MHz.   
We can populate the board with a wide variety of processors so if you are looking for a different processor or crystal frequency please let us know.

Schools, Students (with valid school ID), and US military personal receive a 10% discount on all products.

Rita-51J Options 1-10 11-
AT89C52 @24MHz  (1 Serial Port) $ 100 $ 90
DS89C420 @24MHz   (2 Serial Ports) $ 125 $ 112
7Ft Cat5e Molded Patch Cable Gray $ 5 $ 4.50
7Ft Cat5e Molded Cross Cable Gray $ 5 $ 4.50
Call or email for information about other processor options. 



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       Last updated 3/18/08