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temperature sensor lm75

  • manisrininvas Thursday, June 15, 2017 4:46 PM Reply


    1) Does any body know ,how to connect the  address pins of sensor to controller (see link provided above).

                   i'm working on atmega32 controller using i2c protocol but we to send slave address but  sensor is only 5pins and no address pins .

    2)  CJMCU-75 LM75 Temperature Sensor-does this sesnor supports atmega32 or no

    SKU: 442774

    CJMCU-75 LM75 Temperature Sensor High-speed I2C Development Board

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  • ebpDoug Friday, June 16, 2017 7:56 AM Reply

    If you look at the data sheet for the LM75, which you can easily find on the web, you will see that there are seven address bits. The "top" four bits are 1001 - this is fixed by the chip design. The "bottom" three bits can be set by connecting the address lines of the chip to ground for "0" or V+ for "1". The final bit in the required 8-bit sequence is the read-write bit, 0 for write, 1 for read.

    [edit: as I suspected, this didn't line up very well first try, and I don't know how to used fixed-width fonts here - I'll try to make it line up better]

    A6 A5 A4 A3 A2 A1 A0 RW

    1   0   0   1   x    x    x

    [edit: looks reasonably OK now]

    A6 1

    A5 0

    A4 0

    A3 1

    A2 x

    A1 x

    A0 x


    In the photo of the back of the board you can see three sets of three solder pads

    GND A2 VCC     GND A1 VCC     GND A0 VCC

    You must connect each of A0, A1 and A2 to either ground (GND) or V+ (VCC) by using a solder blob or soldering a short piece of wire to connect the appropriate pads. You must not leave these address selection pins open-circuit which makes their logic state undefined and very susceptible to noise.

    Example - if you connect A2 to VCC, A1 to GND and A0 to GND, the full address would be

    10011000 - to write the device

    10011001 - to read the device

    You must be careful to have only one device at any particular address on the I2C bus. Usually this isn't a problem with simple systems. As long as there are no other devices with 1001 for address bits A6..A3, you could use up to 8 of these boards on one I2C bus by setting A2..A0 for each board to a different address.

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    post edited by ebpDoug on 6/16/2017 at 8:04 AM
  • manisrininvas Friday, June 16, 2017 12:56 PM Reply


    does this is compatiblity with ATmega32 microcontroller or not .thank you

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  • manisrininvas Saturday, June 17, 2017 6:33 PM Reply

    GND A2 VCC     GND A1 VCC     GND A0 VCC

    should A2 A1 A0  connect to gnd of micro controller or  module ground    A2->GND ,A1-GND,A0->GND

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  • Maye_Tao @DX Staff @DX Staff Thursday, June 22, 2017 11:37 AM Reply

    Hello @manisrininvas

    does this is compatiblity with ATmega32 microcontroller or not

    Yes, it does.

    Be happy. ( *^_^* )
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