June 16, 2002
June 16, 2002
June 19, 2002
7.730.1 - 7.730.6
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Interfacing a Graphics LCD to a DSP via a Micro-controller – Simple Distributed Processing used to Enhance the Integration of DSP and Micro-controller Courses in an EET Program.
Anthony J. A. Oxtoby, Christopher S. Arndt Purdue University, West Lafayette IN/Xilinx Inc., Boulder CO
Abstract This paper describes a hardware arrangement that allows data transfer between the 16-bit fixed point ADSP2181 digital signal processor and a Seiko G1216 graphical LCD via an 8-bit 80C552 micro-controller. In this application, the LCD is used to display the results of a 128-point DFT implemented on the ADSP2181 operating at a sampling frequency of 22.05kHz. The interface, however, provides a more broadly useful mechanism to connect slow external devices to the DSP processor without incurring the wait states that are necessary when interfacing directly to the DSP memory spaces and to offload the processing associated with data manipulation and handshaking with these devices. It also provides a link connecting content of the two required microprocessor courses in the EET undergraduate program.
Introduction The sequence of required microprocessor based courses in the EET program at Purdue University consists of an introductory sophomore level course based on the 80C552 micro-controller and an introductory DSP course at junior/senior level using the ADSP2181 1 digital signal processor. The DSP course includes the operation and programming of a fixed-point processor and then moves on to cover the theory and implementation of common DSP applications such as filtering, audio effects and the DFT/FFT.
Because of the hardware emphasis in the course, interfacing to I/O devices has been included, permitting some external interaction to take place with the DSP algorithms. Directly interfacing such devices to the processor memory spaces reduces algorithm speed because wait states are needed in any transactions with these slower I/O devices. One alternative approach is to use serial data transfer through the processor’s serial ports and perform all the necessary scaling in the DSP. Another is to use an external controller to handle the acquisition and scaling of data and the appropriate handshaking for slower I/O devices along with relaying data to and from the DSP processor via direct memory access. Simple circuitry to implement the data transfer and handshaking has been developed and is now included in selected laboratory exercises. This way one can extend the interfacing options in the course, take advantage of a wider range of I/O devices such as push buttons, LCD displays, multi-channel ADCs etc. and provide a direct link to earlier micro-processor courses. Student projects can also take advantage of this technique.
Microprocessor Hardware The DSP course uses the ADSP-2181 based EZ-Kit Lite, an inexpensive yet versatile development system from Analog Devices. Incorporated onto the EZ_KIT Lite is a 16-bit fixed point, 30ns ADSP-2181 processor with 16k words of internal data memory, 16k words of
Proceedings of the 2002 American Society for Engineering Annual Conference & Exposition Copyright Ó 2002, American Society for Engineering Education
Oxtoby, A. (2002, June), Interfacing A Graphics Lcd Display To A Dsp Via A Micro Controller Simple Distributed Processing Used To Enhance The Integration Of Dsp And Micro Controller Courses In An Eet Program Paper presented at 2002 Annual Conference, Montreal, Canada. 10.18260/1-2--10197
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