serial_graphics_tablet
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— | serial_graphics_tablet [2007/07/26 16:32] (current) – created - external edit 127.0.0.1 | ||
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+ | Below is an edited extract from an [[http:// | ||
+ | If you are the original author of this post and wish to have it removed, please contact me through the Private Messages at midibox.org/ | ||
+ | |||
+ | DrBunsen. | ||
+ | |||
+ | |||
+ | '' | ||
+ | '' | ||
+ | '' | ||
+ | |||
+ | This letter discusses using Mac compatible digitizing tablets to get high | ||
+ | resolution data ... since you are not afraid to program, you might try the following: | ||
+ | |||
+ | I assume the MacTablet connects to the Mac using a serial port... | ||
+ | |||
+ | Listen to the tablet using terminal software (Versaterm, naacterm ...)(try 9600 baud as an initial guess at the baud rate.) | ||
+ | |||
+ | The tablet probably sends a 5 byte data packet of the following form: | ||
+ | |||
+ | ^ b7^ b6^ b5^ b4^ b3^ b2^ b1^ b0|bits of a byte | | ||
+ | | P| 1| 0| 0| 0| S| 0| 0|P is parity. | ||
+ | | P| 0| x5| x4| x3| x2| x1| x0|low 6 bits of x data | | ||
+ | | P| 0| x11| x10| x9| x8| x7| b6|high 6 bits of x data | | ||
+ | | P| 0| y5| y4| y3| y2| y1| y0|low 6 bits y data | | ||
+ | | P| 0| y11| y10| y9| y8| y7| y6|high 6 bits y data | | ||
+ | |||
+ | |||
+ | b6 is 1 only at the start of a 5 byte data packet. | ||
+ | |||
+ | This data is drawn from a Summagraphics data sheet for their Bit Pad 1 | ||
+ | digitizer. | ||
+ | |||
+ | Unlike the Mac, point (0,0) is probably at the LOWER-left corner. | ||
+ | |||
+ | If you get data that is consistent with this, then you need only write a | ||
+ | basic program to read data at the serial port. Tablets generate so much data | ||
+ | that you're program had better check the fullness of the serial buffer and | ||
+ | throw away 5 byte data packets periodically to keep the buffer from | ||
+ | overflowing. | ||
+ | compiled Pascal, that was fast enough to keep up with the data rate. | ||
+ | |||
+ | Low-resolution Kurta tablets and other-than-MacTablet Summagraphic tablets use this data format when they | ||
+ | are not transmitting data as strings of ASCII, base-10 integers. | ||
+ | |||
+ | Kurta' | ||
+ | MacTablet, sends 2400 baud, their other models generally run at 4800 baud. | ||
+ | Kurta also makes a MacXL compatible version. | ||
+ | |||
+ | Disclaimer: My opinions are solely my own, but, in evaluating them, you | ||
+ | should know that I am currently re-writing Kurta' | ||
+ | |||
+ | --- David Phillip Oster -- "The goal of Computer Science is to\\ | ||
+ | Arpa: o...@lapis.berkeley.edu | ||
+ | Uucp: ucbvax!ucblapis!oster |
serial_graphics_tablet.txt · Last modified: 2007/07/26 16:32 by 127.0.0.1