1 Reply Latest reply on Jun 9, 2010 6:54 PM by benjaminkropf

    Error In pull-up mode


      hi friends, i was making a simple keycheck program, i selected the pins(p1.0, p1.2, p1.4, p1.6), where i connect push-buttonsand made them in pull-up mode so that on pressing the key, ground makes the pins active.


      But on selecting all these 4 pins to pull-up mode, i realised that only p1.0 was initally pulled up but no other pin was pulled up , though i selected all the 4 pins to be in  pull-up mode.


      I need help, as i need 4  buttons to run my project, so whats the probllem with this, or is there any other solution to it.




      my program:






      mov REG[PRT1DR], 255




      TST REG[PRT1DR], %00000001


      jnz nextkey


      call tx_front






      TST REG[PRT1DR], %00000100


      jnz nextkey1


      call tx_back






      TST REG[PRT1DR], %00010000


      jnz nextkey2


      call tx_left






      TST REG[PRT1DR], %01000000


      jnz keypad


      call tx_right




      jmp keypad

        • 1. Re: Error In pull-up mode


          I don't see anything that immediately looks wrong with this code.


          What does the code in your "tx" functions look like?


          Are you doing any ANDs or ORs with the PRT1DR register anywhere else. If you are, this can cause the pull up drive mode to get disabled on other PRT1DR bits.