OTAU - Size of external flash

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Hi

I am designing a PCB using the Zigbit module. I saw in one of the docs that in order to support Over the air upgrades an external flash must be connected to the SPI port. Even though they make suggestions as to which flash IC's to use there is no indication of the minimum size of this flash.
Does anybody know what size this must be?
What is the flash used for?

Last Edited: Fri. Oct 16, 2015 - 02:28 PM
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It should be at least twice the size of MCU internal flash (better make it 4 times large). So for mega1281 minimum size of the external flash should be 256 KBytes.

Flash is used to store received image and store backup image.

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Thanks for such a speedy answer :)
Just one more question - I see that a UID chip is used to provide a unique 64 bit mac address for each unit. Apart from making using this IC or making a separate image for each unit , are there any other suggestions?

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Depends entirely on your imagination. For example you can have one image for all devices and program (store to the EEPROM) during QA testing via UART. You can even have some default UID and program the real one over the air.

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okay maybe this is a stupid question but I have not used these devices before / yet - does this apply even if using serialnet AT commands - if so would there be any way of setting this number over the air?

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With SerialNet you will be able to set UID via UART ("at+gsn=1234123412341234" command), but not over the air.

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I thought that it also allowed for Remote AT commands that could be sent to other devices over the air? Are there exceptions to what can be done remotely - or is it just because you need the unique number before you can do anything over the air?

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Yes, you need to set UID before you could join to the network. Again, in production you may setup one device to some default value, dump EEPROM contents, flash this EEPROM image to all produced devices and then program correct value OTA. But then you'll also have to setup it to automatically join to the network on power on.

Be aware that OTA firmware update is not possible with SerialNet. And generally OTA is very resource consuming piece of code.

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Thanks for the info.
What happens if another manufacturers device is using a profile that is not understood by this module? I see other manufacturers have a method where they pass any un-interpreted data out of serial port so that host processor can 'decode' it - What does Zigbit do?

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No, SerialNet shows only the data it can recognize (appropriate format, endpoint, profile and cluster). SerialNet was not designed to be interoperable with other devices. It is a very limited to its application area tool, so don't expect too much from it, if you need more - use C API.

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If I use SerialNet will the devices be able to opertae with other manufacturers devices using HA profile?

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No, not even close.

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Okay so if I understand you correctly, if my products needs to be interoperable with third party devices running HA profile I will need to use the bitcloud API and do some of the development myself?

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Yes, actually quite a bit of development. Profiles are not that simple as they sound, but BitCloud Profile Suite contains examples of HA applications.

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Sorry if I am just missing it. I looked at the sample code that comes with the software and I dont see anything that resembles HA?

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You need to download BitCloud Profile Suite, but I'm afraid there is no PS for ZigBits, they don't have enough RAM.

It is still possible to write application level support for HA devices. Without overhead of carrying full-blown ZigBee Cluster Library (ZCL) implementation there is a good chance to fit into 8 kB of RAM. But there are no examples for this, all you have to do is register endpoint with correct ProfileID and ClusterIDs and then handle incoming messages according to specification.

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Thank you Alexru for your answers.

So what devices does Atmel sell that will be suitable for this application? I am afraid I have used Atmel products for years but their 'new' web site really makes things difficult to find :(

Its a pity that Atmel does not make the fact clear on their web site that these modules have some serious limitations. They go on about applications being home automations and also about using standards etc. Perhaps I am completely missing the point. What use is a 'standard' like Zigbee if each vendor implements something that cannot work with other vendors???? sigh

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There is so much stuff going on and it is so hard to make it clear to all people. But after some digging and research it is obvious even from Atmel's site that there is ZigBee stack and there is Profile Suite on top of this stack. And from downloads section it is clear that there is no PS SDK for ZigBit.

Everything works with other vendors. On ZigBee level you can send arbitrary data to arbitrary devices - that works fine on ZigBit. Then you have HA Profile that defines what this arbitrary data should be to be interoperable on the HA Profile level. This works too, but our implementation is not just for HA, it is complete implementation of ZigBee Cluster Library (ZCL). Naturally it requires more resources, but at the same time provides ability to easily run other profiles (SE, CBA, Health Care, etc).

But you don't need to have that complex system. If you need only HA, you may start with ZigBee (which is perfectly interoperable) and build only HA stuff on top of without implementing generic functions from ZCL. HA implementation will require some work, of course, but it is certainly doable.

So all products can work together, it is just we target larger devices with our Profile Suite.

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The most common devices we target with Profile Suite are: megaRF, Xmega256-series, Cortex-M3.

LE: I would suggest you to try megaRF, it is a nice MCU, it is available now, it is cheaper than ZigBit.

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Thanks for that - as I explained - new to this - but keen to get going. I see what you said regarding what was available for download. I thought it was all part of the BitCloud_ZIGBIT_1_12_0 that is why I did not realize it was missing.

Where does one find the megaRF on the Atmel site - gee that site really sucks - I am sorry to say :(

Is it a complete radio module or does one need to build own module - I can do micros but not much of an RF engineer

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Here is information: http://www.atmel.com/dyn/products/product_card.asp?part_id=4692

It is a micro, but there are a few modules based on it, I don't know how good they are though.

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