New Micros, Inc - using A/D and floating point

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JRobertson

08-01-00, 11:16 AM

Hi again, I'm trying to receive inputs on the A/D ports and manipulate the results using floating point words. When I output the results, i get data that is completely off the mark, and in addition, the output of the last value on the floating point stack results in a crash. Any ideas would be helpful, my code is below.thanks, Jay _____________________________________________ HEX: INIT-A2D 80 B039 C! ;: GETVOLTAGE 0 B030 C! BEGIN B030 C@ 80 AND UNTIL B031 @ D>F ;: GETPRESSURE 1 B030 C! BEGIN B030 C@ 80 AND UNTIL B032 C@ D>F 1.0 F- ;: GETCURRENT 2 B030 C! BEGIN B030 C@ 80 AND UNTIL B033 C@ D>F .050 F/ 20.0 F* ;DECIMAL: GETLOAD GETCURRENT GETVOLTAGE / ; : GETFLOW GETPRESSURE 8.35 F* .1679 F+ ;: DOWNLOAD GETFLOW GETLOAD GETCURRENT GETPRESSURE GETVOLTAGE ; : OUTPUT CR ." VOLTAGE " F. CR ." PRESSURE " F. CR ." CURRENT " F. CR ." LOAD " F. CR ." FLOW " F. CR ; : GO! DOWNLOAD OUTPUT ; _____________________________________________

nmitech

08-01-00, 12:14 PM

You are using wrong floating format,DECIMAL : GETFLOW GETPRESSURE 8.35 F* .1679 F+ ;Try this, DECIMAL : GETFLOW GETPRESSURE 835E-2 F* 1679E-4 F+ ;

rob

08-01-00, 02:37 PM

Also you need to have two entries on the stack to use D>F ( d -- ) (F: -- r ). So instead of:: GETVOLTAGE 0 B030 C! BEGIN B030 C@ 80 AND UNTIL B031 @ D>F ;: GETPRESSURE 1 B030 C! BEGIN B030 C@ 80 AND UNTIL B032 C@ D>F 1.0 F- ;: GETCURRENT 2 B030 C! BEGIN B030 C@ 80 AND UNTIL B033 C@ D>F .050 F/ 20.0 F* ;Try:: GETVOLTAGE 0 B030 C! BEGIN B030 C@ 80 AND UNTIL B031 @ 0 D>F ;: GETPRESSURE 1 B030 C! BEGIN B030 C@ 80 AND UNTIL B032 C@ 0 D>F [ DECIMAL ] 1.0E F- ;HEX : GETCURRENT 2 B030 C! BEGIN B030 C@ 80 AND UNTIL B033 C@ 0 D>F [ DECIMAL ] .050E F/ 20.0E F* ; I also corrected the floating point words with the appending of E. Also, know that floating point numbers can only be entered when in DECIMAL radix. That is why I switched to DECIMAL in the middle of the word.Rob

JRobertson

08-02-00, 11:29 AM

Thanks for the replies. I've been trying just to read in a voltage on the A/D port and can't find anything in the Max-forth documentation or the 68hc11 docs about what is actually returned to the result registers. I'm measuring voltages between 0 - 24 volts, and I'm using 1k and 4.3k resistors as a voltage divider. For testing purposes, I'm just attaching the lines to a variable source. When I read the data in the register, I get either -209 (for voltage over 5 out of the source) or somewhere around 25000 (for voltages under 5). Can anyone think of a reason why I'm not getting good numbers?These microprocessor and forth manuals aren't very clear about much of anything.Thanks, Jay

rob

08-14-00, 06:12 PM

Since you are getting negative numbers and numbers like 25000, you are reading more than a byte. Use C@ to access 8 bit wide registers and you will only get unsigned 8 bit values. There are several sources for A/D on the web as well as in the Motorola literature. Sometimes it just takes patience to read the highly condensed technical documents but usually the information is there.