Bluefruit UART Friend suitability

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NYSTEVE
 
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Bluefruit UART Friend suitability

Post by NYSTEVE »

My project involves connecting an Icom IC-705 amateur radio transceiver to a small terminal that I designed. The terminal has a TTL two wire serial port and the radio has a Bluetooth serial port for controlling the radio. This type of radio control is usually done through a phone or tablet with Bluetooth, but in this case I want to control the radio with my TTL serial terminal.
In other words, I need the Bluefruit UART Friend to act as a bidirectional serial port, with the radio communicating via its Bluetooth serial port and the Bluetooth UART Friend presenting and receiving ASCII characters via TTL to my terminal at a standard baud rate (non critical). I goal is to emulate a standard wired serial port between these two devices, but the usual real hardware serial port on the radio has been replaced with a Bluetooth equivalent running a simple serial protocol, with no handshaking.

Can the Bluefruit UART Friend be used in this mode?

Thanks

Steve Silverman

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adafruit_support_mike
 
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Re: Bluefruit UART Friend suitability

Post by adafruit_support_mike »

It depends on which version of Bluetooth you need.

'Bluetooth' is a collective term for a group of mostly-incompatible protocols managed by the same industry group. Many wireless Serial connections use the one now known as Bluetooth Classic, which is only friendly to dues-paying members of the BT Working Group (around $5k/year last time I checked, IIRC). BT-C requires all devices to obey defined device profiles, which is great for compatibility but makes it hard to develop new kinds of device.

When things like the Fitbit started to become popular, it became clear that there was a lot of money looking for a more flexible wireless protocol. The BT Working Group responded by taking over a protocol formerly known as Wibree and calling it Bluetooth Low Energy. BLE specifies some basic rules about how data is organized, but doesn't have mandatory device profiles, and doesn't require paid vendor IDs.

There's a fairly standard way to implement a Serial connection in BLE, but that connection is different from a BT-C Serial connection. The two can't talk to each other at all.

All of our devices use BLE, so the Bluefruit UART Friend will only do what you want if your radio uses BLE as well.

NYSTEVE
 
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Re: Bluefruit UART Friend suitability

Post by NYSTEVE »

Hi Mike

Many thanks for your reply. The Icom 705 radio uses BLE and supports the SPP serial protocol. We want to use your BLuefruit BLE device to pair with the radio so that we can establish two way serial data communication with the our SideKar terminal which supports TTL Rx/Tx data at any baud rate. Note that no computer, phone or tablet is involved in this arrangement. In other words, there is no BLE host in the normal sense. We are hoping that the radio will see the Bluefruit BLE device as the "host" that allows two way serial I/O as though a traditional device that supports BLE/SPP was connected.

I think this is the reverse of how the Bluefruit BLE device was intended to function with the computer or tablet being the BLE host with the Bluefruit's BLE TTL serial port connected to the user device. Will I be able to use the Bluefruit BLE device to communicate with the radio as described above?
Thanks
Steve

NYSTEVE
 
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Re: Bluefruit UART Friend suitability

Post by NYSTEVE »

Hi Mike

After I sent my reply today, I found the following link on your website that was very useful. https://learn.adafruit.com/introduction ... troduction

So in short, the Icom 705 radio is an LE Peripheral and is intended to connect to a Central device such as a tablet. We need the BlueFruit LE UART to act as though it is a Central device in order to connect with the radio as an LE Peripheral. Then we can use the Bluefruit's UART to talk to our terminal. Is this possible or do you know of another device that can do this?

Steve

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Re: Bluefruit UART Friend suitability

Post by adafruit_support_mike »

NYSTEVE wrote:I think this is the reverse of how the Bluefruit BLE device was intended to function
Very much so. No Bluetooth protocol has a concept of a connection wthout a central device.

Bluetooth Classic was originally developed as a wireless substitute for USB cables, so many of the basic ideas apply to both. There’s no such thing as a USB cable that lets a hard drive talk to a printer, or lets a keyboard talk directly to a modem.

Bluetooth has a similar topology. The central device initiates and controls all data connections. Peripheral devices emit advertising packets to let any nearby central device know they exist, but otherwise wait for a central to open a connection and tell them what to do.
NYSTEVE wrote:We need the BlueFruit LE UART to act as though it is a Central device in order to connect with the radio as an LE Peripheral.
The BLE UART Friend is only a peripheral. It can’t operate as a central.

The only device we carry that works as a BLE central is the nRF52840:

https://www.adafruit.com/?q=nrf52840&sort=BestMatch

It has enough CPU and RAM to run the BLE central code stack.

Once you havs the nRF52840 running as a central, it does support wireless UART and should be able to talk to your Icom 705.. assuming the Icom 705 uses BLE instead of Bluetooth Classic.

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