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Interface with 3.3v devices — Parallax Forums

Interface with 3.3v devices

RShirleyRShirley Posts: 12
edited 2005-07-27 18:08 in General Discussion
Hi all,
I am tring to talk· to a Trimble GPS module which is 3.3v. Its comm lines are CMOS compatible. I think·the GPS tx·to Javelin rx·would work.·I don't think it would be safe to connect straight·from the Javelin tx to the GPS rx, 5v driving 3.3v.·Any ideas?
Thanks, Russell

Comments

  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-07-27 18:08
    You are correct that you can feed a 3.3V signal into the javalin and be able to properly read the value under all but the noisiest of conditions. To step the Javalin's 5V down to 3.3V you should use a voltage divider, typically the values of 1.8 kΩ and 3.3 kΩ are used. http://www.captain.at/electronics/pic-mmc/·shows a schematic for connecting a 5V microcontroller with a 3.3V device (a MMC in this case), note the voltage dividers for the /CS, DATA IN and CLK lines (all inputs for the MMC).

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