Bluetooth and 900MHz Feather Help

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cgeoca
 
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Joined: Tue Sep 18, 2018 6:43 pm

Bluetooth and 900MHz Feather Help

Post by cgeoca »

Hello everyone, I'm a senior electrical engineering student at Texas A&M
working on a senior design project. Our group was looking at ordering part
numbers 3133, 3178, 3055, 3242, 2472, 1327 and we have a few
questions.


1. Can we stack the Adafruit Feather With LoRa 900Mhz (part number 3178),
Adafruit Feather 32u4 Bluefruit LE (part number 3242), Adafruit Ultimate GPS
FeatherWing (part # 3133), and Adafruit 9-DOF Absolute Orientation IMU
Fusion Breakout - BNO055 (part # 2472) altogether but have the Bluetooth
send the data from the Adafruit 9-DOF Absolute Orientation IMU Fusion
Breakout while the 900MHz board sends data from the GPS FeatherWing?

2. Can we use one Adafruit Feather With LoRa 900Mhz and one Adafruit Feather
32u4 Bluefruit LE to receive signals from multiple Adafruit Feather With
LoRa 900Mhz and multiple Adafruit Feather 32u4 Bluefruit LE or do we need to
have the same amount of boards receiving and sending boards?

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adafruit_support_mike
 
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Joined: Thu Feb 11, 2010 2:51 pm

Re: Bluetooth and 900MHz Feather Help

Post by adafruit_support_mike »

1) All the physical and electrical connections will work. There are no conflicts there.

Whether you actually get any useful information is less certain though. GPS modules basically watch 100W light bulbs 12,000 miles away, so the signals are right down at the low end of what's physically possible to detect. Putting other radio signals within a few centimeters of the GPS module could easily cause interference. The same is generally true for the 900MHz and BLE radios. Of the three, I'd expect the 900MHz radio to be most likely to interfere with the others.

2) You need one packet radio module at each end of each connection. One Feather with a packet radio can talk to many other packet radio modules, and all the other modules will be able to talk to each other.

The Feather BLE modules can't talk to each other at all.

Bluetooth isn't a peer-to-peer protocol. It splits devices into 'central' and 'peripheral' cagtegories. Central devices initiate and control all data connections, while peripherals mostly wait for a central to tell them what to do. That arrangement puts most of the cost and complexity in the central device, which is usually a full-scale computer. The central software stack is too large to run on most microcontrollers, so the Feather BLE boards we carry only work as peripherals.

The only board we carry which can act as a BLE central is the nRF25 Feather:

https://www.adafruit.com/product/3406

It uses a module specifically designed for BLE applications. Even with that though, BLE is a poor choice if you want peer-to-peer communication.

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