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  1. Home
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SI7021 boards

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  • M m26872

    @GertSanders Link?

    A Offline
    A Offline
    AWI
    Hero Member
    wrote on last edited by AWI
    #9

    @m26872 Industrial High Precision Si7021 Humidity Sensor Module With I2C Interface link

    1 Reply Last reply
    0
    • G Offline
      G Offline
      GertSanders
      Hardware Contributor
      wrote on last edited by
      #10

      Without LDO, but with pull up resistors (smallest board I could find):
      http://www.aliexpress.com/item/Industrial-High-Precision-Si7021-Humidity-Sensor-with-I2C-Interface-for-Arduino/32524005324.html

      With LDO:
      http://www.aliexpress.com/item/Si7021-Industrial-High-Precision-Humidity-Sensor-with-I2C-Interface-for-Arduino/32529522264.html

      M 1 Reply Last reply
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      • G GertSanders

        Without LDO, but with pull up resistors (smallest board I could find):
        http://www.aliexpress.com/item/Industrial-High-Precision-Si7021-Humidity-Sensor-with-I2C-Interface-for-Arduino/32524005324.html

        With LDO:
        http://www.aliexpress.com/item/Si7021-Industrial-High-Precision-Humidity-Sensor-with-I2C-Interface-for-Arduino/32529522264.html

        M Offline
        M Offline
        m26872
        Hardware Contributor
        wrote on last edited by
        #11

        @GertSanders and @AWI Thanks!

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        0
        • Carl HC Offline
          Carl HC Offline
          Carl H
          wrote on last edited by
          #12

          Your plan is it to change your narrow board with SDL/SDA pad. maybe a jumper to change D2/D3 pin to SDL/SDA?

          1 Reply Last reply
          0
          • G Offline
            G Offline
            gloob
            wrote on last edited by
            #13

            It`s a mess that the pinout of both modules is different.

            1 Reply Last reply
            0
            • G Offline
              G Offline
              GertSanders
              Hardware Contributor
              wrote on last edited by
              #14

              @Carl-H it's a possibility. No plans yet, other projects ongoing.

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              • F Offline
                F Offline
                fleinze
                wrote on last edited by
                #15

                I just received some si7021 boards from china. They are with LDO and level shifter, similar to
                http://www.aliexpress.com/item/Si7021-Industrial-High-Precision-Humidity-Sensor-with-I2C-Interface-for-Arduino/32529522264.html
                (the original offer went offline, it was from a reseller named "home boutique", no idea why they sold this item)
                If I use them with a battery node, is it sufficient to remove (and short-cut) the LDO or do I need to remove the level shifter too?

                A ? M 3 Replies Last reply
                0
                • F fleinze

                  I just received some si7021 boards from china. They are with LDO and level shifter, similar to
                  http://www.aliexpress.com/item/Si7021-Industrial-High-Precision-Humidity-Sensor-with-I2C-Interface-for-Arduino/32529522264.html
                  (the original offer went offline, it was from a reseller named "home boutique", no idea why they sold this item)
                  If I use them with a battery node, is it sufficient to remove (and short-cut) the LDO or do I need to remove the level shifter too?

                  A Offline
                  A Offline
                  AWI
                  Hero Member
                  wrote on last edited by
                  #16

                  @fleinze I would suggest to leave these as they are and measure the consumption. Removing the LDO didn't give me a noticeable difference. It could depend on the board however.

                  1 Reply Last reply
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                  • F fleinze

                    I just received some si7021 boards from china. They are with LDO and level shifter, similar to
                    http://www.aliexpress.com/item/Si7021-Industrial-High-Precision-Humidity-Sensor-with-I2C-Interface-for-Arduino/32529522264.html
                    (the original offer went offline, it was from a reseller named "home boutique", no idea why they sold this item)
                    If I use them with a battery node, is it sufficient to remove (and short-cut) the LDO or do I need to remove the level shifter too?

                    ? Offline
                    ? Offline
                    A Former User
                    wrote on last edited by
                    #17

                    @fleinze I am using ATmega328 with 1Mhz and with LDO i have 15uA in standby mode. I have removed the LDO and measured 8uA. You should try it yourself.

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                    0
                    • F fleinze

                      I just received some si7021 boards from china. They are with LDO and level shifter, similar to
                      http://www.aliexpress.com/item/Si7021-Industrial-High-Precision-Humidity-Sensor-with-I2C-Interface-for-Arduino/32529522264.html
                      (the original offer went offline, it was from a reseller named "home boutique", no idea why they sold this item)
                      If I use them with a battery node, is it sufficient to remove (and short-cut) the LDO or do I need to remove the level shifter too?

                      M Offline
                      M Offline
                      m26872
                      Hardware Contributor
                      wrote on last edited by
                      #18

                      @fleinze I wrote a few words about it over here http://forum.mysensors.org/topic/3049/slim-node-si7021-sensor-example/

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                      0
                      • F Offline
                        F Offline
                        fleinze
                        wrote on last edited by fleinze
                        #19

                        @m26872 @kenci @AWI Thank you very much for your answers!
                        I will go for removing the LDO but letting the level-shifter in place, because it is a pain in the ass to bypass the levelshifter.

                        Bypassing the desoldered LDO is very easy. Just connect the following point on the resistor-array:
                        0_1455974189828_gy21.jpg

                        A 1 Reply Last reply
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                        • F fleinze

                          @m26872 @kenci @AWI Thank you very much for your answers!
                          I will go for removing the LDO but letting the level-shifter in place, because it is a pain in the ass to bypass the levelshifter.

                          Bypassing the desoldered LDO is very easy. Just connect the following point on the resistor-array:
                          0_1455974189828_gy21.jpg

                          A Offline
                          A Offline
                          AWI
                          Hero Member
                          wrote on last edited by
                          #20

                          @fleinze The 662k on this board has a typical drop-out of 250mV and power consumption of only 1uA... and takes care of a stable power supply. I doubt if there is any advantage in bridging or removing the LDO.

                          662k
                          0_1456149818998_upload-5b22a252-988a-4acd-b4d8-15be0500a58c

                          si7021
                          0_1456149758981_upload-6a1d2eb3-c0c8-4556-a701-7d2e5db8608c

                          G 1 Reply Last reply
                          0
                          • A AWI

                            @fleinze The 662k on this board has a typical drop-out of 250mV and power consumption of only 1uA... and takes care of a stable power supply. I doubt if there is any advantage in bridging or removing the LDO.

                            662k
                            0_1456149818998_upload-5b22a252-988a-4acd-b4d8-15be0500a58c

                            si7021
                            0_1456149758981_upload-6a1d2eb3-c0c8-4556-a701-7d2e5db8608c

                            G Offline
                            G Offline
                            GertSanders
                            Hardware Contributor
                            wrote on last edited by
                            #21

                            @AWI What happens when the input voltage drops below 3.1V ? It seems the output voltage just follows the input voltage minus the dropout. I have not measured this yet, but I'm assuming this, since i have nodes working below 3.1V and sending temperature and humidity readings.

                            A 1 Reply Last reply
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                            • G GertSanders

                              @AWI What happens when the input voltage drops below 3.1V ? It seems the output voltage just follows the input voltage minus the dropout. I have not measured this yet, but I'm assuming this, since i have nodes working below 3.1V and sending temperature and humidity readings.

                              A Offline
                              A Offline
                              AWI
                              Hero Member
                              wrote on last edited by AWI
                              #22

                              @GertSanders No conclusive reading from the datasheet. I will do some measurements later. ..

                              0_1456219785462_upload-af85eb98-f577-4011-96e9-ef35b5ef97bb

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