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This is a pretty broad question, but I'm curious to hear how people would go about this and what parts they would use to do the heavy lifting.

Imagine you had a bluetooth module, it works fine and can be reprogrammed to act as a central device without too much fuss. You want to bridge data from your bluetooth peripheral devices to a wifi network. How would you go about this? would you pick a wifi MCU like a TI CC3200 or Freescale (NXP) KW series and just connect it directly to the bluetooth module? Or would you want an intermediate microcontroller like a PIC32 to do some of the heavy lifting and have a separate module for the WiFi too? What would your reason for either be?

Edit: To be more transparent, I've noticed a few IoT systems which have a bluetooth-wifi bridge component, which usually have a wifi and bluetooth module, then an additional microcontroller in between. WunderBar is a good example of this. Why would you bother with an additional microcontroller if you were using something as capable as a CC3200?

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  • \$\begingroup\$ There are a ton of options and a ton of reasons why any of those are good. What data are you sending, and how did you want people to access it? A website? A custom protocol? \$\endgroup\$ – Passerby Jan 13 '16 at 22:57
  • \$\begingroup\$ I was curious about why wunderbar have an additional microcontroller between modules since I was considering making something similar. \$\endgroup\$ – Sensors Jan 13 '16 at 23:52
  • \$\begingroup\$ What makes you think that the Wunderbar can act as a Bluetooth-WiFi bridge? It certainly has BT & WiFi, but I don't see any indication that it 'bridges' the 2 of them together. \$\endgroup\$ – brhans Jan 14 '16 at 0:23
  • \$\begingroup\$ @brhans it's purpose is to read multiple BLE connected sensors, and upload them to the web via wifi \$\endgroup\$ – Passerby Jan 14 '16 at 0:33
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Personally, I'd hack one of the cheap routers like the TP-Link TL-WR702N. It can run OpenWRT, and has a Serial interface to talk to your Bluetooth module. This way, you can for example create a python script which relays the data between the bluetooth module and a computer on the same network as the router via TCP sockets.

Everything is integrated, available from many places, and this popular solution is widely supported and documented pretty much everywhere on the web. Very little electronics unfortunately/fortunately (depending on what you want to learn or what your field is).

Of course, you can also do pretty much the same thing with a Raspberry PI or simular using Wifi and bluetooth dongles.

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Based on https://developer.relayr.io/documents/WunderBar/MM its clear they didn't want to design a wifi module from scratch, so they used an off the shelf wifi module, that handles most of the wifi & tcp-ip overhead, and is FCC certified for modular usage. It reduces their coding and manufacturing overhead. They use a Freescale K series ARM chip for encryption, and translating the raw sensor data. The BLE chip again seems to be used for offloading any Bluetooth operations.

Had they used a Freescale KW instead, it would have to be able to do both the standard WIFI, TCP-IP, SSL requirements, as well as their own code. And they would have to design a board, likely multilayer, with 802.11b/g/n RF considerations, antenna choices, shielding. Then they would have to get it tested with the FCC. Iron out bugs. The costs probably exceed any benefit.

As to why they didn't use something like the KW30Z, a Kinetic with BLE IC, that's just a guess, but maybe they got better support or a pre-built firmware for the Nordic than they would have with Freescale? It does seem to be almost double what the KW30Z would be, which is only 20 cents more than the existing MK22FN512VDC12, but looking at the specs, the K22 microcontroller is 120MHz with 128KB Sram and 512KB flash, while a comparable BLE Kinetis microcontroller is only 50MHz/20KB/160KB. They obviously needed more power from the microcontroller than using a single IC would have allowed. So they went with a bigger (and more expensive) IC because of processing needs.

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