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 USB Data acquisition with PIC18F4550 This project is simple and small component count USB data acquisition or USB DAQ. The main core of USB device is PIC18F4550 .The firmware for PIC modified from Microchip CDC library. I use Delphi 6 on PC side to communicate with PIC18F4550 source code availible. Specifications - 8 Digital output - 8 Digital input - 8 Analog output - No external power required - Simple ASCII command - 3 command to communicate PC with PIC  Figure 1 Schematic Command Command  PC Send PIC responeWrite digital output *ANS#13-Read digital input *B#13*BHH#13Read analog input *AK#13*AKXXXX#13When : N = bit that we need to set or clear (0-7) S = state of bit (0-1) HH = Input status from digital input port (00-FF) K = Channel of analog input ( 0-7) XXXX = analog input value in decimal of 10 bit binary (0000-1023 ) #13 = end of command Example to set bit 0 of digital output *A01#13 Example to clear bit 0 of digital output *A00#13 Example to read digital input *B#13 then PIC respone with *B7F#13 This mean bit 7 of digital input was low Example to read analog input channel 4 *C4#13 then PIC respone with *C41023#13 This mean that analog channel 4 have 5 volt on this channel becuase 1023 = 3FFh  Figure 2 PC side software |
When connect this USB Data acquisition with PC then windows ask for driver after driver installed(only first time) you will have a new COMx if not connect the COMx not create by Windows. How to set configuration please read this article Zipped file consist of : - Firmware examples with source for C18 Compiler - Delphi 6 example with source - Windows device driver (Win2K/XP) source code Relate articles Brief USB definition USB CDC example Control stepping motor with UCB |
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