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MT8880 wiring with BS2p40 — Parallax Forums

MT8880 wiring with BS2p40

nathalie.rohrbachnathalie.rohrbach Posts: 2
edited 2012-07-31 07:16 in General Discussion
Hi everyone!
I'm new on his forum, so i hope i post my questions in the right place..I couldn't find answers in other posts. I know this is not really a problem with a parallay chip, bu since i use them in the project too maybe some of you would already have the same propblem...

I'm on a project that uses a emitter/receiver DTMF (MT 8880) wired to a bs2p40. Others MT8880 wired to bs2p (each) are waiting for the first MT8880 to emit "his" code and then need to answer it by emitting an answering-code. The problem is there are only 2 wires. One for the ground and one for the power and signal (still don't know how we're gonna manage that^^). So my questioin is about the MT 8880: As the transceiver needs to be emitter and receiver without having wires moved, can i just wire the tone out pin from the MT 8880 to the IN- pin from the mt8880 without having problem ?Or do i need to place some other devices to be able to do this?

Thanks for your help already!
Nath

PS: Sorry for my english if it's bad...this is not my mother tongue...

Comments

  • stamptrolstamptrol Posts: 1,731
    edited 2012-07-30 07:30
    Welcome to the forums.

    The tone input and tone output can be connected together as shown in the attached diagram I found online.

    alarm_phone_dialer_schematic.png


    Cheers,
    alarm_phone_dialer_schematic.png
    953 x 575 - 80K
  • kwinnkwinn Posts: 8,697
    edited 2012-07-30 17:22
    The tone in of one chip can be connected to the tone out of another chip as shown in the Mitel data sheet figure 3 as long as you also have a common connection. You can also use 2 wires to provide power and a signal path as long as you use capacitors to couple the input and output signals from the powr line to the chip.
  • nathalie.rohrbachnathalie.rohrbach Posts: 2
    edited 2012-07-31 07:16
    Hello!
    Thanks stamptrol and kwinn. I don't have the same datasheet as you do, figure 3 is not showing what yours apparently shows . Where did u find the datasheet you're writing about? Can you give the link?
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