topic Re: Problem reading input port state while using KBI with FRDM-KE02Z40M in Kinetis Microcontrollers https://community.nxp.com/t5/Kinetis-Microcontrollers/Problem-reading-input-port-state-while-using-KBI-with-FRDM/m-p/359168#M18121 <HTML><HEAD></HEAD><BODY><P>Problem solved.&nbsp; Timing issue.</P></BODY></HTML> Fri, 06 Mar 2015 14:40:24 GMT gregs5451 2015-03-06T14:40:24Z Problem reading input port state while using KBI with FRDM-KE02Z40M https://community.nxp.com/t5/Kinetis-Microcontrollers/Problem-reading-input-port-state-while-using-KBI-with-FRDM/m-p/359166#M18119 <HTML><HEAD></HEAD><BODY><P>Implementing a serial input decode routine.&nbsp; Serial input is an asynchronous 18 bit non-standard signal.</P><P>Setup input pin with KBI interrupt on negative edges.&nbsp; KBI interrupt routine looks for space pulse.&nbsp; Works great. (Toggling an output pin to show synchronization)&nbsp; After space pulse detection, enabling a compare timer to latch-in the port pin state.&nbsp; (I do also have an issue with this timer pushing the sample time to the desired position, but there is adequate sample delay to get a valid read as-is.)&nbsp; The problem seems to be when the GPIO port is read.&nbsp; It always reads zero.&nbsp; This seems strange because within the debugger, the input register appears to show the desired bit toggling states.&nbsp; Ironicly, if I do an arbitrary read of the same register within the main() loop instead of inside the interrupt loop, where I need it, it appears to be reading data with the desired bit toggling.&nbsp; I thought perhaps having the KBI enabled had something to do with it.&nbsp; Does not seem to.&nbsp; I've tried tying the pin to another input port just configured as an input only.&nbsp; Same results.&nbsp; Two PDIR bits toggle, but the bits I want always read zero.&nbsp; I've tried all sorts of different troubleshooting.&nbsp; It always comes back to the same conclusion.&nbsp; Not being able to read the port pin data while within the interrupt loop?</P></BODY></HTML> Wed, 04 Mar 2015 21:38:45 GMT https://community.nxp.com/t5/Kinetis-Microcontrollers/Problem-reading-input-port-state-while-using-KBI-with-FRDM/m-p/359166#M18119 gregs5451 2015-03-04T21:38:45Z Re: Problem reading input port state while using KBI with FRDM-KE02Z40M https://community.nxp.com/t5/Kinetis-Microcontrollers/Problem-reading-input-port-state-while-using-KBI-with-FRDM/m-p/359167#M18120 <HTML><HEAD></HEAD><BODY><P>Would you please share your project? I would like to check on my FRDM-KE02Z40M.</P><P></P><P>Best Regards</P><P>Paul</P></BODY></HTML> Thu, 05 Mar 2015 02:34:30 GMT https://community.nxp.com/t5/Kinetis-Microcontrollers/Problem-reading-input-port-state-while-using-KBI-with-FRDM/m-p/359167#M18120 Paul_Tian 2015-03-05T02:34:30Z Re: Problem reading input port state while using KBI with FRDM-KE02Z40M https://community.nxp.com/t5/Kinetis-Microcontrollers/Problem-reading-input-port-state-while-using-KBI-with-FRDM/m-p/359168#M18121 <HTML><HEAD></HEAD><BODY><P>Problem solved.&nbsp; Timing issue.</P></BODY></HTML> Fri, 06 Mar 2015 14:40:24 GMT https://community.nxp.com/t5/Kinetis-Microcontrollers/Problem-reading-input-port-state-while-using-KBI-with-FRDM/m-p/359168#M18121 gregs5451 2015-03-06T14:40:24Z