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' ----------------------------------------------------------------------------------- ' Auswirkungen von "Output Drive Strength Select" verdeutlichen. Mit Scope messen. ' In OCBASIC 1.11a für Open-Maxi von Dietmar Harlos am 8. September 2017. ' ----------------------------------------------------------------------------------- ' Das Controllermanual MC9S08AW60.pdf schreibt dazu: ' "An output pin can be selected to have high output drive strength by setting the ' corresponding bit in one of the drive strength select registers (PTxDSn). When high ' drive is selected a pin is capable of sourcing and sinking greater current. Even ' though every I/O pin can be selected as high drive, the user must ensure that the ' total current source and sink limits for the chip are not exceeded. Drive strength ' selection is intended to affect the DC behavior of I/O pins. However, the AC ' behavior is also affected. High drive allows a pin to drive a greater load with the ' same switching speed as a low drive enabled pin into a smaller load. Because of ' this the EMC emissions may be affected by enabling pins as high drive." ' EMC: Electromagnetic Compatibility ' EMV: Elektromagnetische Verträglichkeit ' "Table A-7. DC Characteristics: ' Output high voltage - Low Drive (PTxDSn = 0): ' 5 V, ILoad = -2 mA: min. VDD-1.5 V ' Output high voltage - High Drive (PTxDSn = 1): ' 5 V, ILoad = -2 mA: min. VDD-0.8 V" ' Für diese Messung wurden 1 kOhm Widerstände an die Ports gegen Masse gelegt. INCLUDE "omax.def" 'Definitionen für die Open-Maxi POKE PTBDS,&b00001111 'Output Drive Strength Selection for Port B 'an PORT[9] bis PORT[12] aktivieren WHILE TRUE portb=&b11111111 'ergibt eine Rechteckschwingung von 43 kHz portb=&b00000000 WEND End2Host=ON 'nach dem Programmende in den Host-Modus END 'Programmende ![]() Meine Homepage: http://ccintern.dharlos.de |
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