SI7021 boards
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Not SI7021 directly, but there are a lot of small sized I2C sensors.
I use a BME280 board on my gateway and on a node.
I also use a BH1750 (slightly bigger) outside to track plants sun exposure.If you end up with a design where the I2C bus is included I can definitively see a lot of uses for it!
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@GertSanders Link?
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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 -
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@GertSanders and @AWI Thanks!
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@Carl-H it's a possibility. No plans yet, other projects ongoing.
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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? -
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? -
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?@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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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?@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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@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
si7021
@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.
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@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.
@GertSanders No conclusive reading from the datasheet. I will do some measurements later. ..
