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Hi all,
Thank you again for your suggestions, they've been very helpful :)
I probably ought to have mentioned this before, but this is my first real foray into electrical engineering (primary focus is as a web developer), so this is still all very shiny, new (and a little petrifying!) to me.
@Gordon, your suggestion of Ciseco modules (particularly ERF/Slice of Radio) sounds really appealing. If I might trouble you for some help, I've a couple of queries;
- Whilst I've reviewed the site's information on MOSFETs, I'm afraid
that I don't know how I could use them in relation to the Espruino's
internal clock for switching serial on and off. Do you know of any
resources you could particularly recommend for this? - The chip antenna is certainly respectable for range, it does seem to
suggest that a wire whip antenna could get that 500m range (300m for
Slice of Radio). However, I've been going completely spare trying to
find anywhere that sells simple 82.2mm wire whip antenna that will
interface with the board - do you or anyone else know where these
can be purchased from, or am I missing a trick?
My apologies if I do seem a little slow on the uptake on this, and again, everyone's help has been nothing short of amazing :)
- Whilst I've reviewed the site's information on MOSFETs, I'm afraid
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Currently, there's no WiFi implementation in the warehouse. I'd definitely considered that as an option, but the main issue is that the power consumption seems to be quite large, from what I've seen. On top of this, WiFi is mostly being implemented in the warehouse for a picking system, so I imagine that that frequency will probably become quite crowded rather quickly.
Obviously, whilst I would want to run some sort of mesh network (either RF or WiFi) this isn't practical with either system when power consumption is a major concern, as I can't afford to leave the transceivers running indefinitely without the batteries going flat in a number of hours. I suppose that I could possibly have the thermometers located remotely with some permanently powered relays, but that will drive the cost up quickly, as well as making the system a lot more complicated to maintain (I should note that I am only on a limited contract with the company, but they have several web and C# developers on site who make up the majority of the IT team - hence the main attraction to a JavaScript interpreter).
LawrenceG, the warehouse isn't chilled, but it is filled with metal racking.
allObjects, you've a fair point - I'd not considered that. Depending on the cost of SD cards, I might float that idea as a failsafe, but my concern is that it will drive the price above the aforementioned data logger.
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Hi allObjects,
Whilst this would be the simplest option by far, my hope is to automate the system as much as possible - going round to various parts of the warehouse and collecting SD cards is going to be seen as a much larger hassle than taking data from a web interface. I'm particularly keen on avoiding physical collection as the other option the company is considering is this thermometer data logger, which is £60 excl. VAT, requires a £44 (excl. VAT) device to plug into a computer, and uses its own specialist software which would require training. As you can see, rather eager to avoid that sort of solution!
Nonetheless, the input is much appreciated :)
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Hi Gordon,
Thank you, that was exactly what I needed! I'll be sure to keep any progress posted :)
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Hello all,
Long time forum skulker, first time speaker. I'm writing in the hope that people might be able to tell me how viable a concept I'm working on is, and if possible, make some suggestions as to better solutions.
The company I'm working for needs to take an audit of temperatures in their warehouse for certain produce. From what scant details I can gather, this doesn't need to be a regular thing - they expect to pull out a graph every quarter or so.
The solution that I'm planning on building would be approximately 5 espruino boards with NRF24L01+ modules and DS18B20 temperature sensors attached. They will sit in deep sleep mode, turning on every 15 minutes to take a reading, transmit and return to deep sleep mode upon a successful transmit, sleeping for 15 minutes minus time taken for transmission. I would ideally want these to be battery powered, hence the deep sleep and sparse readings, and plan on using the recommended 1400mAh Lithium Polymer battery. I've had people voice concerns about range for the aformentioned radio transmitters, I would hope to eek out about 50m for very small and infrequent packets of data.
So far, so normal. However, this is where I'm at a slight sticking point - I want to have a Raspberry Pi handling the receiving and processing. (Ideally, this will be happily sat plugged into a wall socket for power). What I would want to do is implement a MySQL database on the Pi, with a web frontend for accessing the data (with the potential for adding a dashboard ala Brian Dorey.com's excellent solar data logger and e-mail notifications should the temperature fall outside of acceptable bounds).
The reason I feel that I'm coming a little unstuck is the Pi - if I implement Espruino on it, I don't believe that I'll be able to implement the database, which is a fairly large sticking point. However, if I don't, I'm not sure if that will make communication between the radio modules a faff.
If anyone has knowledge on these matters, any guidance would be greatly appreciated.
Kind regards,
MetallixBrother
Software engineer in training, currently on placement year before completing final year at Bournemouth