Portable Remote Control Device

Project Description

The project includes the creation of hardware and firmware to implement a remote control device (pendant) that attaches to a military backpack mounted VHF transceiver. The device was required to meet various rigous environmental criteria, including extreme temperature range, immersion in seawater, EMI/EMC, night vision compatibility and various human engineering factors. The device was also required to small, lightweight, rugged, and inexpensive enough to be disposable. Minimal power drain was also a major concern.
Various areas of development were involved. On the hardware side, selection of components (display & keyboard) small enough to meet the requirements was a major challenge, in addition to packaging all the required parts. This requirement lead to the design of a custom case and keyboard.

Circuitry to accomplish the task was completed in about 2 weeks, and a PC “brassboard” was created for the firmware development effort. While the firmware was being created, the various electrical and mechanical parts were specified and obtained. A PC board (6 layer) was designed and fabricated, along with 2 flex circuits. Prototype units were built (along with PC boards) and programmed in less than 1 month from the final selection of a display. Prototype units powered up and operated with no electrical and minimal mechanical modification. Once prototypes were delivered, the customer began testing. Units passed most tests with little or no rework. Initial documentation (suitable for production) was completed 2 months later. Product now in active production

Skills Required

  • Microprocessor system design (MC68HC908 in this case)
  • Analog design techniques
  • Packaging design (electronic enclosure)
  • Knowledge of EMI/EMC/Tempest requirements and documentation
  • Specification of custom electronic components
  • Design of field firmware upgradable products

Services Used

  • Creation and fabrication of hardware (electrical/mechanical)
  • Selection of appropriate components and custom assemblies
  • Working with vendors to create and implement a custom keypad, switches, controls, and case
  • Working with the firmware engineer to create the system’s firmware per defined specifications
  • Creation of product test plans (hardware and software)
  • Documenting product for production at a contract assembly house
  • Consulting with vendors and customer to achieve a producible product

Project Size

  • Development: 3 man months
  • Documentation for production: 2 man months
  • Firmware: Create, test, document: 2 man months (completed by another ESI employee)


Major manufacturer of military communications devices and RF transmitters.