lee_man_tbu
New Member
Hi everyone,
I have an application where i want too use a PIC MCU too dial a phone number, someone at the other end of the phone number answer the phone, maybe talk too the person operating the PIC through a Speaker and then when the user pushes the "9 Key", the PIC will accept that DTMF code and perform the next operation. IE controlled entrance on an apartment building.
I understand how too decode in coming DTMF signals, my problem is the dialing circuit. I need too know if anyone has any idea's on circuits for this application. IE a digital "Hook", Isolating the PIC from the high voltages from phone lines ect. I know i will probably be using the Pulse Width Modulator too generate the DTMF signals or if an acceptable IC is available too generate DTMF's, i am just unsure of the circuits.
if anyone has any idea's for me, that would be great.
Thanks
Lee
I have an application where i want too use a PIC MCU too dial a phone number, someone at the other end of the phone number answer the phone, maybe talk too the person operating the PIC through a Speaker and then when the user pushes the "9 Key", the PIC will accept that DTMF code and perform the next operation. IE controlled entrance on an apartment building.
I understand how too decode in coming DTMF signals, my problem is the dialing circuit. I need too know if anyone has any idea's on circuits for this application. IE a digital "Hook", Isolating the PIC from the high voltages from phone lines ect. I know i will probably be using the Pulse Width Modulator too generate the DTMF signals or if an acceptable IC is available too generate DTMF's, i am just unsure of the circuits.
if anyone has any idea's for me, that would be great.
Thanks
Lee