Hello all, I have been messing around with Arduino and other microprocessors for a little while. I am interested in making a low power (aka battery based) project that gathers temperature from several server rooms in a 5 story building.
I think the Moteinos may be a good fit and I am trying to determine which wireless module would be the best. I am having a difficult time determining what the main differences are between the different radios. I figured I am probably going to use the 900Mhz version (I'm in the US)....and if I had more range I could hook up other buildings that are next door or a few doors down.
Any help would be greatly appreciated.
If it helps: I have a few locations already hooked up using Particle.io Photon microprocessor.
Thanks,
Jim
Quote from: jimbrown on April 30, 2016, 09:31:07 PM
Hello all, I have been messing around with Arduino and other microprocessors for a little while. I am interested in making a low power (aka battery based) project that gathers temperature from several server rooms in a 5 story building.
I think the Moteinos may be a good fit and I am trying to determine which wireless module would be the best. I am having a difficult time determining what the main differences are between the different radios. I figured I am probably going to use the 900Mhz version (I'm in the US)....and if I had more range I could hook up other buildings that are next door or a few doors down.
Any help would be greatly appreciated.
If it helps: I have a few locations already hooked up using Particle.io Photon microprocessor.
Thanks,
Jim
Welcome,
Are all your nodes battery operated or are some (like those in 'other buildings') powered from the mains? The reason I ask is less about the frequency (915MHz in US is fine) but more about the available power at those nodes. You can get a very good range from Moteinos but you'll have to pay in electrical power.
Tom
Tom
Well, I do have mains power (120volt) and was thinking about having a "hub" or master node that was connected to my lan at all times running on the building power. The rest of the nodes that are reporting temperature would be battery powered. I was thinking about having them sleep for a period of time, wake up, see if the temp was in between a "normal" range, record the value and then go back to sleep. A sleep period of 5 to 10 minutes maybe more should be fine. Once every few hours, the unit could wake up and report the values via wireless. If there was a reading outside of "normal" range it could also transmit without having to wait the several hours.
Any help would be greatly appreciated.
Thank you again,
Jim
RFM69 & Moteino will give you plenty of range for your application and would be easy to build basic nodes with just Moteino & Weathershield boards.
Where you'll need to do a bit of learning and work is getting decent battery life (months or years) with this combination. You'll have to remove a few parts and reprogram the core fuses & bootloader to reduce quiescent power consumption (the biggest consumer of power in a low duty cycle device). Cut quiescent power consumption by 2 (easy to do) and you've almost doubled your battery life.
I'd recommend getting a couple of the boards I mentioned, play with them and get them working together. Then study some of the posts in Low Power Techniques section of this forum. You'll find plenty of help here.
Also, for your 'hub', I'd recommend the Moteino Mega for several reasons: 8X RAM, lots of program space, and more peripheral interfaces to support LAN connection.
Tom
UPDATE: fix RAM size, it's 16KB on Mega, 2KB on 328P.
Tom, can I ask a few more questions:
1. Is there any reason you did not recommend the LoRa Chipset? The only thing I could determine is that the firmware/drivers are not as fully developed compared to the RFM69 chipset?
2. For low power would you recommend the extra "memory chip" when I check out? I could see the ability to store data values for several wake up cycles and/or the ability to reprogram the chip over the air could be helpful.
3. Again, for low power would you recommend having the USB soldered on or should I go with the non-USB and use the USB adapter for initial programming?
Thank you again for all your help,
Jim
Quote from: jimbrown on May 01, 2016, 09:40:32 PM
Tom, can I ask a few more questions:
1. Is there any reason you did not recommend the LoRa Chipset? The only thing I could determine is that the firmware/drivers are not as fully developed compared to the RFM69 chipset?
Yes. The RFM69 is an excellent radio that will meet your needs. It will provide higher bandwidth at lower power with a richer set of software to support it. LoRa is for an entirely different set of applications, eg those requiring KM type of range at low bandwidth.
Quote
2. For low power would you recommend the extra "memory chip" when I check out? I could see the ability to store data values for several wake up cycles and/or the ability to reprogram the chip over the air could be helpful.
It depends. The flash chip is primarily used for the Wireless Programming Library where you can update the firmware on the mote wirelessly after the mote is deployed. It can also be used for logging (I have done this as well). However, the flash chip used on the Moteino is not the lowest power flash and if you are trying to get the longest battery life then there are lower power alternatives. These will cost you, however, as you will need to modify and maintain a variation of the SPIFlash library. If your current consumption target is 5-10uA while sleeping, the 'standard' flash will be fine. If you're trying to get to sub uA currents, it is not.
Quote
3. Again, for low power would you recommend having the USB soldered on or should I go with the non-USB and use the USB adapter for initial programming?
What do you mean by "USB soldered on"? Do you mean the FTDI header connector or are you looking at the Moteino USB version? If the latter, then this is not a low power device and I don't think that 'not soldered on' is an option. If you mean FTDI connector, then, sure, if you plan to use it and you have room for it, it doesn't consume any power if not used. You can leave it disconnected without a problem and its there if you need it.
Tom
Tom, I have another question. I'm trying to figure out if I should purchase the RMF69W or RFM69HW. I understand the H would be a "higher output" but this would also use more battery power. From what I read there is an amplifier on the board to make it a "higher output". Can I purchase the HW version and disable the amplifier in the software if it is not needed...or should I just go with the standard version and hope that I have enough signal to get to where I am going?
Also, you mentioned earlier to purchase a MEGA unit for my "master" unit. You stated that I could wire up an Ethernet module to this so I could get the data online. Do you have any recommendations on a specific Ethernet module?
Finally, what is the best way to power these when I do begin using battery power. Would 2x AA be what I want?
Thank you again for all of your help,
Jim
Quote from: jimbrown on May 06, 2016, 08:06:19 PM
Tom, I have another question. I'm trying to figure out if I should purchase the RMF69W or RFM69HW. I understand the H would be a "higher output" but this would also use more battery power. From what I read there is an amplifier on the board to make it a "higher output". Can I purchase the HW version and disable the amplifier in the software if it is not needed...or should I just go with the standard version and hope that I have enough signal to get to where I am going?
if the distance you are trying to cover is relatively short (<100 feet), there are no massive obstructions, and you can deploy a reasonably decent antenna (straight wire = 1/4 wave length is perfect), then the W version is all you need. HW will consume considerably more battery power but will also permit you to communicate over a larger range (roughly 2X). No, you can not remove or disable the power amplifiers on a HW. You can dial back the transmit power and the HW has +7DBm higher output power with coarser granularity on power control.
UPDATE: For your 'hub' I would recommend using the HW as it will need to reach ALL nodes in its network. Only nodes that are far away from the hub may need the HW.
Quote
Also, you mentioned earlier to purchase a MEGA unit for my "master" unit. You stated that I could wire up an Ethernet module to this so I could get the data online. Do you have any recommendations on a specific Ethernet module?
W5100 is pretty much the standard ethernet module for Arduino nodes. This uses SPI interface. It is what I use for my Gateways that use Ethernet interface. You can find breakout boards for relatively low cost on eBay. Bear in mind that these will require a 5V power supply. The electrical interface to Moteino is 3.3V, but you need 5V for the ethernet connection.
Quote
Finally, what is the best way to power these when I do begin using battery power. Would 2x AA be what I want?
Uh, this question has many answers, but, for you just starting out, I'd recommend 2 X Lithium AA (Everready Ultimate) connected to the Vin pin of the Moteino. These will supply 3.4V nominally and will operate down to -20C without any complaints. You will need to learn how to run the Moteino in a low power state and there is a wealth of information on this site - probably too much for a beginner. You'll need the latest LowPower library.
Tom
Is over the air firmware/software feature available with Lora modules, particularly at lower data rates?
Thanks
Quote from: John_L on June 17, 2016, 06:47:06 PM
Is over the air firmware/software feature available with Lora modules, particularly at lower data rates?
Thanks
Not right now, not with the RadioHead library. If I ever make my own LoRa library I will also include OTA support, if that is feasible given the very low data rates these modules operate at.
Quote from: John_L on June 17, 2016, 06:47:06 PM
Is over the air firmware/software feature available with Lora modules, particularly at lower data rates?
Thanks
See my response in: https://lowpowerlab.com/forum/index.php/topic,1966.msg14334.html#msg14334
You could roll your own fairly easily as long as the bootloader is the same.
Tom