skip navigational linksPJRC
Shopping Cart Checkout Shipping Cost Download Website
Home MP3 Player 8051 Tools All Projects PJRC Store Site Map
You are here: CCD Array Reader Project Overview Search PJRC

CCD Array Reader
Main Page
TC102-1 CCD Image Chip
selected Project Overview
Design Data
Testing, Actual Output

Introduction

The CCD (Charge Coupled Device) Array Interface is a general purpose board which continually scans a one dimensional 128 element light sensitive array and produces a stream of digital output codes corresponding to the measured light intensity at each pixel element. The 8-bit output values represent the relative energy absorbed at each pixel during the interval in which the last set of data was sent. While these seems quite intuitive, the TC102-1 CCD array chip provides only a raw sensor array; built-in features implemented in the hardware on the CCD Array Reader Board deliver the easy-to-use digital data stream.

Automatic High-Speed Scanning

All timing operations are generated on the board, which simplifies its usage, and allows the array to be scanned at relatively high speed. The various clock signals required by the TC102-1, A/D converter, analog circuitry and the computer interface's handshake lines are all created by digital circuitry on the CCD Array Reader Board. This relievs the computer from the task of controlling the CCD Array and associated circuitry so that it may acquire data more rapidly. The CCD Array Reader Board includes built in power supply circuits to generate a number of voltage levels required by the various components; the user only need provide a plus and minus sixteen volt power supply. Finally, a ten pin connector and cable are provided so that the data may be read in by a computer. Two special handshake signals are provided on this interface connector which make to task of acquiring the data relatively simple. Though the CCD Array Interface board is quite complex, these features make its usage quite simple.

Automatic Offset Adjustment

The board features automatic self calibrating offset adjustment, to compensate for the varying voltage offset levels produced by the CCD Array component. This offset correction technique results in pixels which receive virtually no light producing a digital code of zero without requiring the adjustment of calibration trim pots for different lighting conditions, scanning speeds, ambient temperatures, or other varying conditions which may change the actual voltage output levels produced by the CCD Array component.

Automatic Gain Control

The board also features automatic sensitivity control, which results in output codes of 255 (the maximum) for pixels which are saturated (the maximum light intensity). The combination of Automatic Offset Adjustment and Automatic Gain Control assure that the output stream will represent the relative range of intensities received by the CCD array using the full dynamic range of the 8-bit data.

Full Saturation Detection

A light emitting diode is provided on the board to indicate a fully saturated condition in which the array has been exposed to so much light that it is no longer functioning properly. If the TC102-1 is exposed to too much total incident energy during a sampling period, its detectors do not operate properly. This condition is detected by the CCD Array Reader Board's circuitry.

Applications

The CCD Array Reader Board is intended to be a general purpose device for use in applications where one dimentional imaging of relative light intensity is required. It was the intention of the OSU Physics Department to use a linear image detector of this nature to acquire position data with time of objects on an air track in ungraduate physics courses. Students would conduct their classical physics lab experiments (with small lights mounted to the objects) and obtain much more data from this board than they would have collected otherwise.

The CCD Array Reader Board was demonstrated using a video camera lens and a small light bulb mounted to a battery. Though it performed very well sampling at relatively high speed, I doubt it has seen any use in undergrad physics labs. In all likelyhood, the board is sitting in the back of some physics storeroom on the OSU campus. Oh well.

Of course, I passed the course with an 'A' and everyone was suprised and impressed that it worked so well. Several others had tried to get these damn TC102-1 chips to work with fairly unimpressive results.


Paul's Simple CCD Array Reader Project, Paul Stoffregen
http://www.pjrc.com/tech/ccd/overview.html
Last updated: February 25, 2005
Suggestions, comments, criticisms?? <paul@pjrc.com>