Manufacturers of Custom and Standard Industrial Embedded Single-Board Computers


Picture of the RPC-220 single-board computer

    • Compact 2.85" x 3.85" size
    • 8 Channel, 10 Bit A/D
    • Low power modes
    • 19 Digital I/O lines
    • PWM, analog out
    • 512K BB RAM
    • Real time clock



The RPC-220 is a compact, 8051 compatible single-board computer used for data acquisition and control. You can cut programming time using any of the application programs included with the development system. Many developers simply take an application program that is close to what they want (analog input, timing measurement, etc) and build upon it. The expansion port and available +/- analog power make connecting to external devices easy.

Its Flash EPROM enables easy field and remote updates. Its real time clock can "wake up" the card and battery back up RAM for over 4 years.

Function Description

Analog Input

The A-D converter has 8 channels at 10 bit resolution. Reference is adjustable from 4.8 to 5.2V. Input range is 0 to reference voltage. Higher input voltages are possible by adding a resistor.

Conversion time is about 50 uS and is triggered in software or externally. Power for signal conditioners is +/-8V at 5 mA and is available at the analog connector.

Use a 20 position ribbon cable (CMA-20) with STB-20 terminal board to break out the signals.

Digital I/O

19 programmable digital I/O lines are available.  Unused analog lines are available for digital inputs for a maximum of 27 lines.  These lines come from CPU port P1, P3, and P4.  Many of these.lines are used for different functions, such as LCD port, software serial port, and interrupts.  The CMA-26 ribbon cable connects J3 to the STB-26 terminal board to break out signals.

  embedded controller fits in hand Tiny embedded controller fits in the palm of your hand!



Two programmable PWM outputs are available.  Duty cycle is programmable from 0 to 100% in 256 steps.  Frequency is from 170 to 43 KHz.  PWM output is used to generate analog outputs.  PWM can be used as digital outputs.  PWM signals come from the digital port.

Analog Output

Two voltage outputs are derived from the PWM signals.  Output range is 0 to 5V.  Effective resolution is 8 bits.  Full scale range depends upon the +5V supply.  Full scale response time is about 200 mS.  Outputs are from the analog connector.


Several of the 80C552 CPU timer lines are available at the CPU port.  Two 8051 inputs, TO and T1, are available for counting or pulse width measurement.  Counter/timer T2 is used to count, measure pulse widths, or control an I/O line on a compare. 

Watchdog Timer

Watchdog timer resets the card if not updated in time in software.  A jumper enables/disables this feature. 

Display Connector

Directly connects to 4 line x 40 character or other size liquid crystal displays.  Contrast/angle adjustment available.  Self running software example included in development system


128K or 512K of battery backed RAM are available for data logging and temporary extended program execution.  Two models are available with 128K of RAM.  Refer to "Ordering Information" on the table for model numbers.   Boards with real time clock back up RAM for 4 to 6 years.  An external connector is available for longer life.

A 32K flash is used to save the application.  As shipped, the flash includes a monitor for development or program downloading.  The monitor is replaced by your program when development is done.  A 64K EPROM can replace the flash.


The Real Time Clock has a century counter and leap year compensation.  It has 114 bytes of battery backed RAM and a unique serial number to identify the card along with other features.

Use the RTC to wake up periodically (once a second or hour) or at a specific date and time.  It can generate programmable interrupts from 2 Hz to 32.768 KHz for additional timing modes. Other registers include power on and total run time for maintenance.  Battery life is 4 to 6 years.  The RTC is not on P/N 1720.

Input Power

The RPC-220 operates from a wide range of voltages.  All cards operate at +5V.  P/N 1710 (included with development kit) allows unregulated inputs from 5.4V to 21V without a heat sink.  Other models need a minimum of 6 volts power input.  Low power modes on P/N 1710 reduce current to about 3 mA.

Serial Port

There is one hardware and an optional software RS-232 port.  Hardware serial port has programmable baud rates from 300 to 57,600.  Data is fixed at 8 bits, 1 start and stop, no parity.  CTS and RTS control lines are jumper optional.  If these lines are not used, they are available as a software UART.  Program examples are provided in the development package.  The CTS line can be used as a high voltage(+/-15 V) input when not used for any serial port.

RS-232 voltages are generated on card. The interface chip that does this can be controlled to turn off RS-232 voltages to reduce overall power consumption.

Use the VTC-9F serial cable to connect between a PC and the card.  The VTC-29F cable has two DB-9 connectors and is used to access both RS-232 outputs.

The I2C serial bus is used to communicate with other CPUs or devices.  These lines are separate from RS-232 and are brought out on the CPU port J3.

Expansion Port

An expansion port brings out control and data signals for you to build your own interface card.  These include 8 data, 5 address, ALE, read, and write signals.  +5 and external high voltage power are also available.  Reset is active low. 

Embedding in a System

The RPC-220 easily plugs into your "mother board" with signal conditioners or other devices on it.  Board power can be applied to, or is available from, many connectors. Pin connectors are on 0.1" centers.  Contact us for a list of suggested connector manufacturers and part numbers.

RPC-220  Development System

Picture of the RPC-220 Devlopment System

A development system has the software and hardware you need to get going.  All you need is a PC with a serial port and a terminal program.  A few megabytes of disk space are used for the compiler, assemblers, application programs, and component data.  Application programs are self running.  You not only get the drivers, but see how they are implemented, and results or status are sent to the screen.

Development System Components

Contact Remote Processing for a list of accessories to accompany the RPC-220.

Ordering Information:


Development System:


RPC-220 with 512K battery back RAM, real time clock, 32K flash EPROM

Development system includes STB-20 and STB-26 terminal boards, serial and interconnect cables, application disk,  CPU technical information on disk, and power supply.

C-compiler  and assembler available from Dunfield . (not included)



Low power version with 512K battery backed RAM, real time clock, 32K flash EPROM



Standard power version with 128K battery backed RAM, real time clock, 32K flash EPROM



Lowest cost version with 128K RAM, 32K flash EPROM.  No real time clock, battery back up, reset switch, or analog output.