I have a general question about how BlueTooth chips are set up:

When you are setting up a bluetooth chip (i.e. installing the firmware which will make the chip do what it needs to) the chip is usually integrated into a board which you connect to your computer so you can install the firmware on the bluetooth chip.

My question is: does this mean when you purchase the individual bluetooth modules on their own, these have to be soldered/integrated onto a circuit with a USB interface each time you need to install firmware onto the bluetooth chip??

For example, if I want to simply have a bluetooth module connected to an LED, and all it is is the module, the battery input, and the LED, and I want to connect to this module using an app on my phone and turn on the LED using my phone. How do I go about installing the firmware onto the chip to do this? Your help is much appreciated. Kindest regards.

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    \$\begingroup\$ It would make your question easier to answer if you added information on where you're going with this design (volume, product or learning), and if there were specific modules you planned to use. \$\endgroup\$ – Sean Houlihane Nov 1 '16 at 8:45

This of course varies by manufacturer but most modern flash based MCUs, presumably including those with bluetooth radios, can have initial programs loaded via an interface such as JTAG or SWD or something vendor unique. To name a few examples from the BTLE realm TI's 8051-core CC254x use their proprietary CC debugger connection, while Nordics nRF51822 use a variation of ARM Cortex SWD (or perhaps optionally full JTAG).

Many also support upload of intial code via a serial UART or various synchronous schemes managed by a bootloader in factory ROM or unmodifiable area of flash. A few do have USB bootloaders but that's less likely to be chosen in production.

Production parts can be programmed either using special fixtures before installation, or after installation using headers, pads for spring plunger contact fixtures ("pogo pins", tag connect, etc) or even special modes of interfaces that will be left for the consumer.

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  • \$\begingroup\$ I would add that some also support OTA (Other The Air) update allowing you to update the firmware over Bluetooth. This (and updates via a serial port) often requires a certain pin to be pulled in the correct direction during power up. This can be done using a jumper or button within the product e.g. hold the button down while you put the battery in to enter update mode. \$\endgroup\$ – Andrew Nov 1 '16 at 9:54
  • \$\begingroup\$ OTA update usually requires first loading a suitable initial firmware. While not impossible its less likely to be a boot ROM feature as it requires a nearly full protocol stack, and those are both big and something you want to be able to keep improving. \$\endgroup\$ – Chris Stratton Nov 1 '16 at 14:11

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