What HW to use?

Hi

I have made a LoRa sender for monitoring a bee hive (weight, humidity and temp). and a receiver. I dont use WiFi in this sender, only LoRa.

When prototype is finished I will make another 10 pcs.

For this test/prototype I have used a ESP8266MOD + DHT20 + HX711 + AI-01 AI-Thinker LoRa module. The prototype works, but it seems to need a reset after boot.
For this prototype I have used all Dx pins + A0, so I don't see how I can add switches to Tare and reset.

I have previously project used a Arduino Pro Mini, and I experienced to be very stable.

Q1:
Can you guy's give me your thought's for what is best microcontroller to use, and also give me your reason? One important issue is that sender must be stable also when in deep sleep mode.

Q2:
Can you see what brand it is?

Thanks up front!

M

Esp32 can get quite low power

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Nice idea - I don't do this for mine as the bees would coat everything in propolis. You can't have a humidity sensor sealed or you won't actually read the humidity. The rest would work well though.

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More links please !

Ai-Thinker LoRa: https://docs.ai-thinker.com/en/lora
Which one do you have ?

Your LoRa module and the ESP8266 or ESP32 seems to be over-the-top. But if they are cheap and available, then it is no problem.
If the LoRa works well, then keeping that module is a good choice. There are other modules.
Arduino LoRa: https://store.arduino.cc/products/arduino-mkr-wan-1300-lora-connectivity
Adafruit LoRa: https://www.adafruit.com/product/3178

I let the Pro Mini behind me long time ago. If the sketch needs to be updated, then I can't find the usb-serial module anymore. If you don't mind about that, and it has enough memory, then yeah, it is a good choice, but so is the Nano and (Pro) Micro and other boards.

I think that the HX711 works best at 5V. Do you want to make your whole project with 5V or with 3.3V ?

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Using a MCU with radio to control another radio seems weird.
And... you need a special (Sparkfun only) HX711 board to connect to a 3.3volt processor (ESP).
Leo..

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Thanks for answer Koepel!

Which one do you have ?

I have AI-Thinker RA-01, runs on 3.3V

The HX711 from Sparkfun runs also on 3.3V

I let the Pro Mini behind me long time ago.
This is exactly what I need to get info about because I don't have much experience.
I have the USB/serial cable with 4 females plugs.

Regarding memory, the sender sketch is not big, it reads 3 values and send 3 values, so I dont think I need a big amount of memory

> A really good programmer/HW/PCB man I discussed with wrote this to me:

For the beehive side I'd be looking at an Arduino Pro Mini board. With the regulator and power LEDs removed it can go super low power, in deep sleep my multimeter can't even measure the current, it's less than 1 µA. Unless you need WiFi there, the WeMOS is not a good choice.

Hi @Wawa

Using a MCU with radio to control another radio seems weird.

Please explain why its weird?

My answer is that I had the microcontroller laying around, and I used it to build a prototype. This tread is for asking you pro forum users to give me advice :slight_smile:

Which controller would you recommend?

Yes, I use Sparkfun 3.3V, more expensive but probably a good choice regarding operation stability.

Hi @outbackhut

Good info. If DHT20 get full with propolis then I assume it still reads temp?
Humidity then will not work, probably not the most critical value to monitor.

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He gave good advice :heart:
With three AA batteries, a stripped Pro Mini is the right choice. You don't need to go much lower than the self-discharge of the batteries. Nick Gammon wrote a good tutorial.
However, you have the LoRa module. Is your project battery operated ? How much does the LoRa module use in sleep mode ?

A Pro Mini of 8MHz 3.3V can also run at 5V (or 4.5 with three AA batteries). I don't know about the other things.

Close, but no cigar.
The HX711 from Sparkfun must be powered with 5volt (4.6volt minimum).
But it is the only available board that can output 3.3volt logic.

If you power that board with 3.3volt, then the 4.25volt excitation won't be stable.
And you are rewarded with a noisy readout.
Leo..

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Hi @Wawa

Interesting what you say about the 4,4 Volt.

My protype I use 3,3 volt and weight is pretty stable, but I will try to use 5V. Before that I red datasheet and Input V from 2,7 to 5,5 V.

Can you/other help me understand this better:
"If you power that board with 3.3volt, then the 4.25volt excitation won't be stable."

Sparkfun HX711
Datasheet: https://cdn.sparkfun.com/assets/b/f/5/a/e/hx711F_EN.pdf

From sheet
image

Misleading image. You should read all of the datasheet.
The chip can work on 2.7volt, but common boards have the excitation voltage set to ~4.25volt with R1,R2. That's why you need at least 0.1 or 0.2volt more than that for the linear pass transistor Q1 to do it's job.
Leo..

I don't have much experience with DHT20 - if humidity isn't critical, consider using a DS18B20 instead - one like this as it is already sealed for being waterproof.
No, humidity isn't a big deal unless you have varroa, but measuring it doesn't help - you need to control the varroa no matter what the humidity is :wink:
I honestly wouldn't bother measuring the humidity - I'd just use a DS18B20 or similar - one that is already waterproof.

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