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HARI krishna
HARI krishna
Associate III
June 15, 2017
Question

can we use uart to communicate wire one wire device

  • June 15, 2017
  • 4 replies
  • 1951 views
Posted on June 15, 2017 at 08:08

Hi all,

I have DS18B20 sensor which works on the one wire protocol & it was interfaced to STM32F030C8T6 controller.

But it was failed to communicate(respond) with the device over UART2.Below is the uart to device connection Fig.

I am using 3.3V for to power the device and 2.2K pull-up on the bus(as mentioned in the datasheet).

How to Generate reset signal (480us low on the bus) on the uart pins for one wired device.

please help me on this issue

UART Connection to one wire Bus :

0690X00000603kHQAQ.jpg
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    4 replies

    HARI krishna
    HARI krishnaAuthor
    Associate III
    June 16, 2017
    Posted on June 16, 2017 at 12:41

    Kindly waiting for valuable replies,

    Can we use gpio to implement one wire interface?

    Tesla DeLorean
    Tesla DeLorean
    Guru
    June 19, 2017
    Posted on June 19, 2017 at 13:52

    Certainly not going to be able to use the USART to implement the 1-wire protocol. Review the protocol and use the RX pin without the other circuitry.

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    Uwe Bonnes
    Uwe Bonnes
    Chief
    June 19, 2017
    Posted on June 19, 2017 at 13:40

    As the ST uart pind can be put into open-drain mode, you can connect the OW device direct to TX with an appropriate pullup provided. Parallel connect RX or with newer the UART revision as found in the F0, use half duplex mode  so no external RX pin is needed. Have a look at Maxim application note AN126.

    Andrew Neil
    Andrew Neil
    Super User
    October 20, 2017
    Posted on October 20, 2017 at 19:28

    Maxim have an App Note on how to do this.

    They also have various 'bridge' chips ...

    A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
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