im new here! and i need help , can anyone help me in how can i interface MT8888C chip with any microcontroller ( i prefer PIC) ? any thing useful ( like codes for example or documents)
im new here! and i need help , can anyone help me in how can i interface MT8888C chip with any microcontroller ( i prefer PIC) ? any thing useful ( like codes for example or documents)
for dtmf tone dialing . because I’m going to design an automatic voice dialer for security system. when it is triggered, the dialer will call a specific number and play a recorded msg.
i have a Question : how can i detect that the line phone has picked up or not or ( busy line ) from the other side by using ( call progress detection of MT8888 chip ) ??
because i read the datasheet and i didn't understand how to use the call progress detection
Hi,
MT8888 can be used as call progress decoder, but you have to analyse the actual tone pattern in software using the microcontroller. As a standard, the tones are centered around 350 to 440 Hz and such frequencies when present on the line will be filtered out and given by MT8888. Since there is a large variation of actual tone pattern for various exhanges and PABXs, a universal tone detector is really difficult, but I think you may get some ICs from NXP Semi.
A usual practice to know automatically if the called party has gone off hook, is by looking at the 'Battery Reversal' signal or the start of Metering Pulse on the subscriber line. But unfortunately, these signals are not extended to the subsriber extensions even though they do it on special request as in the case of private telephone booths.
Hi,
Please Google for Call Progress Decoder, there you can see the chip NE5900 from Phillips Semi. I do not have any codes, with this chip, you can directly get the decoded tone nibble. If you want to do the DTMF way, you have to find out in software the frequency of the incoming tones and their modulating patterns.
Regards, Laktronics