SkyView




Claudia Mojica


James Benoit
 

Jesús Galván


José Guerrero

Objective

Design an interface package to communicate between the R - cubed parallel port from the Data Link Transceiver (DLT) to the Universal Asynchronous Receiver-Transmitter (UART) serial connection from the GPS receiver.

 

Abstract

Based on the experience designing, testing, and implementing circuit boards of our engineers we recommend the development of an interface package to communicate the R - cubed parallel message from the DLT to the serial connection from the GPS receiver. The current Serial to Parallel Converter (SPC) design is problematic for tracking high-speed targets due to a fixed frequency of 1 Hz and a 19.2 Kbps. This new Interface Format Translator (IFT) design would include a custom-made interface board, to translate the military based parallel port, and a PCM - 3350 board to perform the message conversion to a RS - 232 serial port, Universal Serial Bus (USB), or Ethernet port. The interface board will accomplish the data transfer with the help of an RCM3400 microcontroller to allow a smooth and ordered message transition. The proposed solution will not only solve the limitation of the SPC but will increase the frequency to 20 Hz and a baud rate of 115.2 Kbps.

 

Method of Completion

The DLT has an R - cubed parallel port which is used to request or inform the GPS receiver of any information.  The personal interface board is designed to translate the messages coming from the R - cubed parallel port from the DLT to the RS - 232 serial port leading into the GPS receiver.  The proposed technique to complete the project of designing an IFT, will involve replacing the current SPC with a personal interface board which will incorporate a PCM - 3350 and a RCM 3400 microcontroller.  The PCM - 3350 consists of one  RS - 232 serial port connection, one USB connection, and one Ethernet connection, which will expand the output capabilities of the IFT. The technique to be implemented will solve any limitations caused by the current SPC, and will increase the transmission frequency to 20 Hz and the baud rate to 115.2 Kbps.

The approach to take in order to complete a successful interface package is to implement a combination of two microprocessors, performing different operations, to achieve complete transmission of the messages at the desired transmission rate. First, the RCM3400 microcontroller will serve as a buffering and latching device to properly transfer the complete message within a 50 microseconds time constraint to the PCM - 3350. Second, the PCM - 3350 will request information from the GPS receiver on the objects location and status

Finally, the messages will be transferred through three output terminals which include RS - 232, USB, and Ethernet. This will provide versatility to the IFT package to empower the user to include several applications in a self-contained box.

With a contract date of October 6th, we would begin the design process for the Interface Format Translator (IFT) package by October 7th. The project would be ready for simulation by December 5th. Complete documentation would be provided at the completion of each phase of the assessment process. We would complete our interface device by mid April and submit our final report by April 29th, 2004. 

 

Issues

Hardware Requirements

The IFT package will be drawing power from the DLT's power supply. This power supply delivers twenty-eight Volts DC. The two different pieces of equipment used in this package, the RCM3400 and the PCM - 3350, require different power supplies. To solve this problem, a DC - DC converter will be acquired to step the twenty-eight volts to the five Volts required by the PCM - 3350. Furthermore, the RCM3400 microcontroller requires only 3.3 Volts to function. A solution to this problem will be to implement a resistor-zener diode circuit configuration with the specific characteristics and tolerances to achieve the desired power supply.

Software Requirements

In order the IFT to operate at fast enough rate to meet the tight timing constraints it is necessary to implement an efficient software code with an efficient operating system. The team's option to this issue is to implement the Real Time Linux. This operating system will enable the team to develop an competent package meeting successfully the IFT's current software constraints and specifications.

Moreover, the RCM3400 microcontroller needs to be programmed using a unique compiler called Dynamic C. This computer software enables the design engineer to do embedded programming in a more efficient way since Dynamic C is C friendly. One of the most important issues to take into consideration when looking at the programming part of the microcontroller is the lack of familiarity with this type of compilers from the SkyView's engineering and design team.

 

Schematics


 

State of Project

PROJECT IN PROGRESS!