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air quality CO2 sensor
#1
Hi

It is possible to use another sensor instead of MH-19Z, I mean LP8 from sense air. Without major software changes. Thank you
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#2
Hi,

Regarding the LP8 from Sense Air, perhaps isn't only a question of changes on the software.
From sensor specs I see: UART and I/O interface voltage - 2.5V
So, you may need logic level shifters.
MeteoCercal - Air Quality Data
Click here to watch at my ThingSpeak channel



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#3
Level shifter are not problem, i have lot of ADUM1201. I have some pieces of LP8, and I thinking about their use.
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#4
(23-05-2019, 06:25)borovecek Wrote: Level shifter are not problem, i have lot of ADUM1201. I have some pieces of LP8, and I thinking about their use.

Oh. I didn't understand why you want to buy such an expensive sensor ...  Wink
Best Regards
Zdenek

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#5
I didn't buy it, I got it exchanged from a friend  Smile
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#6
(23-05-2019, 06:25)borovecek Wrote: Level shifter are not problem, i have lot of ADUM1201. I have some pieces of LP8, and I thinking about their use.

Hi,

I think ADUM1201 isnt suitable to use withthe LP8

The ADuM1200/ADuM1201 isolators provide two independent isolation channels in a variety of channel configurations and data rates (see the Ordering Guide). Both devices operate with the supply voltage on either side ranging from 2.7 V to 5.5 V, providing compatibility with lower voltage systems as well as enabling a voltage translation functionality across the isolation barrier.

The LP8 I/O interface is 2.5V
MeteoCercal - Air Quality Data
Click here to watch at my ThingSpeak channel



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#7
Ok, my fault, i didn´t seen to datasheet of adum1201 for minimal voltage of logic. But i think, there isn´t problem with voltage level ESP8266 on WEMOS. Here is example with arduino, and there is 5V logic, and in another example with Raspberry is 3V3 logic. Maybe extra precautions is add resistor on RX and TX signal. But this is only idea
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#8
Or maybe something like this Logic converter
41south.net.nz powered by WeatherDuino and Weewx
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#9
(24-05-2019, 06:11)borovecek Wrote: ...
Maybe extra precautions is add resistor on RX and TX signal. But this is only idea

Smile Even simple! With the Wemos you may only need a simple resistor voltage divider on the RX line of the sensor. The 2.5V TX output level of the sensor will be read as logic 1 by RX on the Wemos.

(24-05-2019, 06:11)borovecek Wrote: Ok, my fault, i didn´t seen to datasheet of adum1201 for minimal voltage of logic. But i think, there isn´t problem with voltage level ESP8266 on WEMOS. Here is example with arduino, and there is 5V logic, and in another example with Raspberry is 3V3 logic.

I may be wrong, so double check:

S8 - I/O 3.3V
LP8 - I/O 2.5V
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