1. saman1969

    Thread Starter New Member

    Nov 2, 2012
    Hi . I try to use a mt8888 for detecting tone from telephony line . unfortunatly i have had a lettel success since now. i think my problem is in initializing or the timing of the mt8888 . because sometimes it works , but most of time it does not work. i use microcontroller "dsPIC33FJ256GP710" in my circut. please help me about this problem . i initialize chip mt8888 as mentioned in its datasheet.
    i use mikroC for compiling my program.
    the section of my code for initializing the mt8888 is
    CS=0 ;
    RS0=1 ; WR=1 ; RD=0 ;
    RS0=1 ; WR=0 ; RD=1 ; B3=0 ; B2=0 ; B1=0 ; B0=0 ;
    RS0=1 ; WR=0 ; RD=1 ; B3=0 ; B2=0 ; B1=0 ; B0=0 ;
    RS0=1 ; WR=0 ; RD=1 ; B3=1 ; B2=0 ; B1=0 ; B0=0 ;
    RS0=1 ; WR=0 ; RD=1 ; B3=0 ; B2=0 ; B1=0 ; B0=0 ;
    RS0=1 ; WR=1 ; RD=0 ;

    After initilizing , by detecting dial tone , IRQ pin should go low , then by reading status register this pin should go back to high . i can not reach this stage. is it possible that initializing is not complete?as pin 24 of my mt8888 goes high by detecting dial tone it seems i should have IRQ interrpu but it does not happen.
    it is appretiated that help me.
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    I believe you should look a little closer at the timing diagram to write to this device. You are sending all the information without any set up or delay time delays.

    Also, you never "clock" the write line, you just set t low and never return it to high.

    (I have no idea what specific data you are sending and if it is correct as I have never used this particular device.)
    saman1969 likes this.