Using RFM69HCW with beaglebone

[manaxmizery]

Hi,

Is there a way to use the RFM69HCW module to send data between an Arduino UNO and Beaglebone Black?

[raggedyanne]

Two modules will talk with same settings, so yes there.
Uno is 328p 5v , module is 3.3v, yes with signal translator & supply is 3.3v
Pro mini is 3.3v 16Mhz, so yes there. (there like $2 for a replica)
I don't know what beagle is, in respect to system or voltage?

[TomWS]

I don't know what beagle is, in respect to system or voltage?

BeagleBone is 5V external supply, 3V internal and signalling.

Tom

[TomWS]

Hi,

Is there a way to use the RFM69HCW module to send data between an Arduino UNO and Beaglebone Black?

A couple of different ways, actually.  Your note implies that the UNO is 'remote' from the BBB and has a RFM69 radio to connect to 'something' at the BBB.  If this isn't what you have in mind, please provide more detail.

As RaggedyAnn points out, the UNO signalling is 5V and this would exceed the 3.3V rating of the BBB.  However, BBB has USB Host support so you could simply attach a Moteino USB or UNO with FTDI cable (operating as a Gateway) to BBB's USB port.    You could also attach a Moteino TX/RX signal directly to the BBB serial ports (which are also 3V signalling).    In my case, I've set up a Moteino Mega Gateway with W5100 Ethernet adapter and used a LAN connection to BBB.   I wouldn't try to port the RFM69 library to the BBB - that, to me, is an exercise in futility given BBB's debian (ie non-realtime) OS and the low cost solutions with an Ardunio/RFM69 combination.

Tom

[raggedyanne]

You can use 74LVC245 logic level converter for spi , fits on a breadboard 

[perky]

You can use 74LVC245 logic level converter for spi , fits on a breadboard 

This only works in general if the Vih spec of the device matches the Voh of the 74LVC245.  The ATmega328P has a Vih of 0.6Vcc which is 3V, so you've only got 0.3V noise margin assuming the 74LVC245 drives all the way to 3.3V. It'll probably work as the current it's sourcing is very low so it'll be close to 3.3V, but it's worth checking any device you're driving that this is sufficient to drive it (a lot of devices for example use 0.7*Vcc and that's 3.5V which wouldn't work).
Mark.

[raggedyanne]

[perky]

What is that table, where does it come from (link please)? The issue is not inputs to the 74LVC245, it's the Voh output of the 74LVC24 meeting the Vih of the device it's driving. This Voh will be close to 3.3V with Vcc of 3.3V due to it driving CMOS inputs (assuming no pull-ups) so is likely to work, but in general you need to check the Vih spec to ensure it works with sufficient noise margin.
Mark.

Edit: OK, I've found it, it's the measurement points in the timing diagrams of the 74LVC245A for the propagation delay specs. These are not relevant at all to the Vil and Voh issue.
Mark.

[TomWS]

You can use 74LVC245 logic level converter for spi , fits on a breadboard 

OP hasn't made it clear what he's connecting to what, but, even so, I fail to see how this device would solve a connection between an UNO and a BeagleBoneBlack. 

The device has only one power rail and if you connect it to the BBB supply (3V), you'll blow out the 245's inputs from the UNO's 5V signals.  If you connect it to the UNO's 5V supply, you'll blow out the BBB's MISO input from the 245.

Tom

[perky]

The 74LVC245 and 74LVC245A parts are 5V tolerant Tom. No problem with the inputs driven at 5V when powered by 3.3V for that device, it's making sure the output voltage which is powered from 3.3V and won't go above 3.3V is enough to meet the Vih of any device it's driving. It's unclear as you say what this connection might be. We don't know whether the OP is talking of interfacing a radio module of some sort directly to the BBB (maybe via a moteino) and transferring the data over radio to a UNO also with some radio module attached or what.
Mark.

[TomWS]

The 74LVC245 and 74LVC245A parts are 5V tolerant Tom. No problem with the inputs driven at 5V when powered by 3.3V for that device

Thanks for the update, Mark.  I appreciate it.

Tom

[perky]

There are so many logic families out there it's sometimes hard to keep track of whether they are truly 5V tolerant or not, some families have 5V tolerant inputs but if they are bidirectional devices the input shares a pin with a tri-stated output which isn't 5V tolerant! Anyway, my guess is what the OP wants to do is interface the BBB to a UNO with a radio module attached to it. Using Linux for real time stuff like low level radio control is not a good idea, you'd want to add a much higher level control like an AT type interface from the BBB and use the UNO's real time processing to actually drive the radio. In which case it's a question of how you interface a BBB to a UNO and the radio is a distraction.
Mark.