@dakipro ah ok you cheated
I thought you kept the plastic layer that's glued on top of the wood panel. I'll try to get some samples from the company selling those here and make some tests then.
Hello, even with transparent plastic bottles there should be enough light reflected to be detected by a ToF sensor like VL53L0X. It's more reliable than most distance sensors that measure the quantity of light that is reflected. It also has the advantage of a much better range compared to other optical distance sensors.
You might even manage to use only this sensor if you put it on top to measure the height of objects and you have enough size differences between the types of containers.
@nca78 ok thaks, so in Your opinion does the module I linked is good for testing/prototyping nrf5 MySensors nodes ?
It is good enough yes, it seems complete, but be careful it also seems to use 2mm headers, so you will need either 2->2.54mm adapters or a custom PCB to use it on breadboard.
Also, you will need a programmer. The cheapest option is making a black magic probe, check the nrf5 thread for that.
Another solution is a NRF52 DK to have both a jlink programmer and all pins broken out to 2.54mm headers (uno format) but it's over 30$.
regarding the low frequency oscillator, here it is written in the "Buying guide" section that "If you plan to make a battery powered sensor, you should choose a module including the low-frequency oscillator (32,768kHz) for precise low power sleep modes". So this is not true as the LF clock is not used by MySensors ?
Maybe I'm wrong when I say it is "not used by MySensors". But the way it is used if it's used is different than in bluetooth mode. Without it with MySensors all you will have is less precise sleeping duration because it will use the internal oscillator. In bluetooth it will use internal oscillator and wake up regularly to calibrate it, resulting in something like 10uA average current consumption, so in that case it's really a big problem. But if you're only planning to use MySensors and not planning to switch to BLE later, you will have 0 real problem without the LF clock.
I'm looking through datasheets and it seems like there is not so much difference between the two. Of course the nrf52832 has more peripherials, memory and is a little bit more low power but those aspects are not so important for my use case. So what would make nrf52832 better for mysensors ? The nrf52832 has -96dBm sensivity at 1Mbps data rate (and do not have 250kbps data rate) and nrf51822 also have -96dBm sensivity at 250kbps data rate. Both have +4dBm transmit power. So for me it looks like if there is no peripherials or memory limitations both chips are equally good for MySensors network.
There is a lot of difference in terms of RAM (16K/64K) and in terms of processing power (64MHz M4 vs 16MHz M0). Even the flash can make a difference as with OTA update you need to split the memory in different parts, so you have at best half of the memory available for your program (for current firmware, and other half for downloading firmware). In reality it's even less than that because you need bootloader, and some part for permanent storage.
In terms of "low power" there's a significant improvement in transmit/receive power, and if you can transmit at 1M instead of 250k for the same sensitivity budget it means you need to transmit only 1/4 of the time, big improvement... With only 50% of sleep power also, there's no comparison NRF52832 is much better.
NRF51 also have some limitations in terms of interrupt, it's a problem for low power nodes as over one interrupt you have to make relatively complex tricks to keep very low power in deep sleep.
Given the low price difference between the 2 chips and all the extra stuff in the NRF52, there is no reason to chose NRF51 now, except if you're really, really tight on budget.
Oh, and could it be used as a gateway also ? I read somewhere that for low power nodes the low-frequency oscillator should be choosed and for normal nodes the high-frequency crystal should be should be choosed. So it seems like the hardware for low power node cannot be also used as a gateway. Is it true ?
If you are using MySensors, you don't care at the LF oscillator, as it is used to keep precise timing in bluetooth mode (node sleeps and has to wake up at a very precise moment to receive messages). In MySensors it's not the same the LF clock is not used. What you need to save power is inductor so the chip can use it's internal DC-DC converter and use much less power when sending/receiving with the radio.
Regarding the high frequency clock you always need one, opposite to the atmega chips you can't set the frequency with the NRF5 chips, NRF51 will run at 16MHz and NRF52 at 64MHz, and for that they need their high frenquency clock. You can see it on the picture of the module, metallic rectangle with a gold "frame", it's written 32MHz on it.
Hello, I have merged your 2 topîcs are they are relatively similar.
- I usually go for the BEM280 instead of the BMP085 and DHT22. It's so cheap now.
Unfortunately most of the cheap breakout boards found on AliExpress use clones with much worse specs than the original version
In fact, I always make all my sensors with the Nano Wireless Expansion Board, which is about $2. You can simply plug in the NRF24 into it.
But you can't really make battery-powered sensors with those ? The regulators are AMS1117 with 5mA typical quiescent current.