Activity

Test.. having problems responding to msg

Hi Shannon, (response to your pvt msg – attempting to post here)
Yes I’ve got some RS485 transducers communicating. I’ve used the Sparkfun version in the past.
The key is that a protocol runs on top of the RS485 – sometimes called modbus – and some people represent it is a set of archaic concepts.
The full modbus may be useful in some SCADA apps, but I think its simpler to think of it as a query and response protocol.
I’ve really managed to make it work by using a Salae logic 8bit analyzer to be able to see what is actually being emitted onto the bus protocol, validate the CRC. I’ve looked at some Arduino libraries, but they appear confusing – maybe I haven’t take the time to make them work. Also it turns out Keller switches the CRC bytes around.

This is my code –
https://bitbucket.org/neilh20/nuttapps/src/c62a41fe9f256076a5ea1aab423a95b9c55b1b30/examples/ae/aelog/?at=work_ensy1b
see ae_mdm_phy.c

This ‘aelog” subsystem reading from a Keller NanoLevel and then sending it to a particile.io photonWiFi, which transmits over wifi to thingspeak.
It has options for other transducers including Insitu, however each transducer manufacturer does a little differently.
The environment is PX4 like (nuttx) , running on an Olimex-H407/, STM32F407/200kram (similar to the emerging Arduino Otto).
I’ve gone with the OlimixH407 as it is industrial quality, has a 12V input and a number of peripherals I need, and plugable RS485.
I’ve been running it off a +12V supply, for the RS485.
I’m about to add a switched 12V boost, which I just realized I can run off the switched USB host +5V
The base Nuttx implements Posix calls, and a shell (linux sh like) Some of which makes life easier, and some of it is going to require Arduino like evolution.
My workflow env http://nuttxworkflow.blogspot.com/2016/05/tutorial-bitbucket-branched-workflow.html

What sensors are you looking at?
What supply voltages do they need?.
How are you connecting into the Mayfly.
I bought a Mayfly mega1284/ram16k, and familiar with its architecture. In a past project used its sibling mega2560/ram8K extensively.
Great to see the work you’ve been doing with the Mayfly, but haven’t had an application for it yet.