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Production design

This report provides the updated schematics, board layouts, and source code for the actual production version of the encoder electronics upgrade. This is what is going into the VLA antennas as you read this.

Schematics and Boards

The schematic images are provided in two file formats: *.gif for easy viewing, and *.ps for better-quality printing. The final board designs are provided as gerber files that you are welcome to make boards from. There are two modifications that you should make, however. These are noted below.

ENCODER COARSE AND FINE DRIVER
Note: we had trouble with using the BRCX11 resolvers at 10kHz. Since the prior resolvers worked great at this frequency I hard wired production board so that the frequency select pins of U3 for 10kHz: pin 1 to VSS and pin 2 to GND. To get the system to work with the BRCX11 resolvers, I changed the frequency to 2kHz by drilling out pin 2 of the board where the socket for U3 sits and connecting pin 2 to pin 1. The schematic reflects this change, but the board is wrong.

ENCODER FINE AND FIBER XMIT
Note:Tie a 10k resistor between pins 3 and 6 of U16, the MAX1232 chip. This chip is the watchdog for the PIC16C55 and the reset line must be pulled up to function reliably. The schematic is correct, but there is no place to put the resistor on the board. ENCODER FIBER/POWER BUFFER FIBER RECEIVER

Source Code

Three programs are provided. Listing enc1x.asm is for the PIC16C55 that resides in the encoder. This program reads the coarse and fine resolver-to-digital converters and ships the data down the fiber. The "1x" designation means that this program works for the 1x gearbox on the coarse resolver. The listing buffer.asm runs the PIC16C55 in the Data Receiver/Buffer which reads the fiber data stream and make it available to the controller. The controller code is enc_kbd.c and is put on the BL1600 EPROM along with the ZWorld BIOS.

These programs are provided in both HTML form for nice viewing in a browser, or downloadable ASCII.

These programs are covered by the Gnu Public License


updated 5/13/2002 - Bob Broilo
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