topic Re: Problem w/ PORTA & B after RESET in S12 / MagniV Microcontrollers https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Problem-w-PORTA-B-after-RESET/m-p/144740#M3786 <HTML><HEAD></HEAD><BODY>Not sure if I understand what you mean. Here is something you should check though:<BR /><BR />PORTA and PORTB doesn't have pull-up enabled out of reset. Unless you write to PUCR or have external pull resistors, you will get random values when the port is configured as input.</BODY></HTML> Fri, 09 Feb 2007 21:46:44 GMT Lundin 2007-02-09T21:46:44Z Problem w/ PORTA & B after RESET https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Problem-w-PORTA-B-after-RESET/m-p/144739#M3785 <HTML><HEAD></HEAD><BODY><DIV> </DIV><DIV>I am using the 9S12XDP512 from TechArts and connecting 3 Lynxmotion Tracker Sensors to PORTA[7:5], PORTA[2:0], and PORTB[7:5]. The Tracker Sensor outputs HI for WHITE light, and LO for BLACK light. I have configured the&nbsp;Data Direction registers for PORTA &amp; B (i.e. DDRA = 0x14; DDRB = 0x1F; ). Also, the MCU provides the +5VDC to power the sensors.</DIV><DIV>&nbsp;</DIV><DIV>The problem occurs when I switch the controller to 'Run' and press the 'Reset' button. Nothing happens, until I place a WHITE sheet of paper under the PORTA sensors. Only then does the program execute. Why does my program require an external event to start?</DIV><DIV>&nbsp;</DIV><DIV>Thanks for your help.</DIV></BODY></HTML> Thu, 08 Feb 2007 02:59:27 GMT https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Problem-w-PORTA-B-after-RESET/m-p/144739#M3785 thesheriff 2007-02-08T02:59:27Z Re: Problem w/ PORTA & B after RESET https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Problem-w-PORTA-B-after-RESET/m-p/144740#M3786 <HTML><HEAD></HEAD><BODY>Not sure if I understand what you mean. Here is something you should check though:<BR /><BR />PORTA and PORTB doesn't have pull-up enabled out of reset. Unless you write to PUCR or have external pull resistors, you will get random values when the port is configured as input.</BODY></HTML> Fri, 09 Feb 2007 21:46:44 GMT https://community.nxp.com/t5/S12-MagniV-Microcontrollers/Problem-w-PORTA-B-after-RESET/m-p/144740#M3786 Lundin 2007-02-09T21:46:44Z