sms to control pic..pls help...


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  1. #1


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    Default TX/RX Connections

    Hello, i'm stucked at the point that our dear PIC works on 5V, and thus definitely the serin/serout would also generate high and low pulses of 0-5v, while the GSM module which i'm having (SIM508) posses serial transmission module of VMax being 3V...and it's been quoted to use a level converter where necessary, so can anyone help me out with this...
    can i use MAX233 in between or would there be any other procedure to follow...

    Best Regards
    Jamshid Dastur

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    Quote Originally Posted by jamshid.dastur View Post
    Hello, i'm stucked at the point that our dear PIC works on 5V, and thus definitely the serin/serout would also generate high and low pulses of 0-5v, while the GSM module which i'm having (SIM508) posses serial transmission module of VMax being 3V...and it's been quoted to use a level converter where necessary, so can anyone help me out with this...
    can i use MAX233 in between or would there be any other procedure to follow...

    Best Regards
    Jamshid Dastur
    Hello Jamshid Dastur, I think a simple transistor would work to switch data @ 5 volts, keeping in mind it would invert the data.
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    Default !!!

    Quote Originally Posted by Joe S. View Post
    Hello Jamshid Dastur, I think a simple transistor would work to switch data @ 5 volts, keeping in mind it would invert the data.
    Hi Joe, are you sure about MAX ic that its not a serial decoder, and just a level shifter, if so...then i can simply use a zener diode to drop voltage and a 40XX buffer ic to up the level without any inversion...

    Best Regards
    Jamshid Dastur

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    Quote Originally Posted by jamshid.dastur View Post
    Hi Joe, are you sure about MAX ic that its not a serial decoder, and just a level shifter, if so...then i can simply use a zener diode to drop voltage and a 40XX buffer ic to up the level without any inversion...

    Best Regards
    Jamshid Dastur
    Aw heck no, I'm not SURE about anything! I thought you wanted to switch a 5v level with 3v, I guess you want to go the other way.
    If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
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    .
    There simply is no "Happy Spam" If you do it you will disappear from this forum.

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    Jamshid, you should use a MAX3232 not a Max233. But there is a simpler way to interface serial TTL to a serial 3V, this is using a partition of resistors. Use for each line (Tx & Rx) 3x10K resistor in series from pic pin to ground. Connect the 3 V serial device to the second resistor so that you have 20K from ground for the 3 V device and 30K for the TTL. This is the system I use and it works fine.

    Al.
    Last edited by aratti; - 24th December 2008 at 21:37.
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