Porting MySensors to work with the RadioHead library
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Reply from Mike:
Some of your contributors have the wrong idea about the headers.
There are 4 header bytes used by drivers, RHDatagram and RHReliableDatagram
TO
FROM
ID
FLAGSThese are the hop-to-hop headers. In fact they are present in the payload (but
effectively unused) even if you use the drivers directly.RHRouter and RHMesh (if you use them) add
DEST
SOURCE
HOPS
ID
FLAGSthese are end-to-end headers and are not necessarily the same as the hop-to-
hop headers. In the general case they will be different values.In my view all these header are all necessary.
BTW, new version 1.33 supports sleep mode for RH_RF69, RH_RF22, RH_NRF24,
RH_RF24, RH_RF95 drivers.Cheers.
@hek said:
Reply from Mike:
these are end-to-end headers and are not necessarily the same as the hop-to-
hop headers. In the general case they will be different values.yep :)
In my view all these header are all necessary.
Well, debatable at least for the FLAGS (or the size of the FLAGS).
Three questions (@Mike, if you are reading here, just reply directly, otherwise I'll contact you via the RH channels...):
- is the RH library itself using the end-to-end FLAGS? I couldn't find any reference other than setting it to 0 (when using RHMesh).
- is the RH library itself using the hop FLAGS for anything other than identifying ACK packets (RH_FLAGS_ACK / RH_FLAGS_NONE)?
- for the hop ID and TO - if the specific RF chip supports this internally (as part of the preamble/header the chip adds to the on-air packet), why duplicating this wasting valuable payload size - the driver for the specific RF chip could handle it internally and make it look the same for the outside world using the RHGenericDriver interface without changes... I'll give it a try and let you know.
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Reply from Mike:
Some of your contributors have the wrong idea about the headers.
There are 4 header bytes used by drivers, RHDatagram and RHReliableDatagram
TO
FROM
ID
FLAGSThese are the hop-to-hop headers. In fact they are present in the payload (but
effectively unused) even if you use the drivers directly.RHRouter and RHMesh (if you use them) add
DEST
SOURCE
HOPS
ID
FLAGSthese are end-to-end headers and are not necessarily the same as the hop-to-
hop headers. In the general case they will be different values.In my view all these header are all necessary.
BTW, new version 1.33 supports sleep mode for RH_RF69, RH_RF22, RH_NRF24,
RH_RF24, RH_RF95 drivers.Cheers.
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Great work guys. I'm glad to see some enthusiasm for this as it will allow me to utilise the platform and not have to reinvent the wheel :-)
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Test compilation comparing code size with current MySensors 1.4 radio library and with radiohead. The radiohead integration to MySensors is not optimized (pushing full MySensors header through even if the radiohead header has the same content etc.) and the radiohead library provides some benefits (not just a 1:1 replacament) - so it's expected to be larger. Based on the two examples below it's right now about 4-5k flash and ~800 ram for global variables.
=> let's see how far we can get that down reducing the duplication of header data etc.
**SerialGateway with MySensors: **
Sketch uses 17,566 bytes (57%) of program storage space. Maximum is 30,720 bytes.
Global variables use 688 bytes (33%) of dynamic memory, leaving 1,360 bytes for local variables. Maximum is 2,048 bytes.SerialGateway with RadioHead:
Sketch uses 22,242 bytes (72%) of program storage space. Maximum is 30,720 bytes.
Global variables use 1,455 bytes (71%) of dynamic memory, leaving 593 bytes for local variables. Maximum is 2,048 bytes.**DallasTemp with MySensors: **
Sketch uses 20,288 bytes (66%) of program storage space. Maximum is 30,720 bytes.
Global variables use 551 bytes (26%) of dynamic memory, leaving 1,497 bytes for local variables. Maximum is 2,048 bytes.DallasTemp with RadioHead:
Sketch uses 24,592 bytes (80%) of program storage space. Maximum is 30,720 bytes.
Global variables use 1,319 bytes (64%) of dynamic memory, leaving 729 bytes for local variables. Maximum is 2,048 bytes. -
Test compilation comparing code size with current MySensors 1.4 radio library and with radiohead. The radiohead integration to MySensors is not optimized (pushing full MySensors header through even if the radiohead header has the same content etc.) and the radiohead library provides some benefits (not just a 1:1 replacament) - so it's expected to be larger. Based on the two examples below it's right now about 4-5k flash and ~800 ram for global variables.
=> let's see how far we can get that down reducing the duplication of header data etc.
**SerialGateway with MySensors: **
Sketch uses 17,566 bytes (57%) of program storage space. Maximum is 30,720 bytes.
Global variables use 688 bytes (33%) of dynamic memory, leaving 1,360 bytes for local variables. Maximum is 2,048 bytes.SerialGateway with RadioHead:
Sketch uses 22,242 bytes (72%) of program storage space. Maximum is 30,720 bytes.
Global variables use 1,455 bytes (71%) of dynamic memory, leaving 593 bytes for local variables. Maximum is 2,048 bytes.**DallasTemp with MySensors: **
Sketch uses 20,288 bytes (66%) of program storage space. Maximum is 30,720 bytes.
Global variables use 551 bytes (26%) of dynamic memory, leaving 1,497 bytes for local variables. Maximum is 2,048 bytes.DallasTemp with RadioHead:
Sketch uses 24,592 bytes (80%) of program storage space. Maximum is 30,720 bytes.
Global variables use 1,319 bytes (64%) of dynamic memory, leaving 729 bytes for local variables. Maximum is 2,048 bytes. -
Test compilation comparing code size with current MySensors 1.4 radio library and with radiohead. The radiohead integration to MySensors is not optimized (pushing full MySensors header through even if the radiohead header has the same content etc.) and the radiohead library provides some benefits (not just a 1:1 replacament) - so it's expected to be larger. Based on the two examples below it's right now about 4-5k flash and ~800 ram for global variables.
=> let's see how far we can get that down reducing the duplication of header data etc.
**SerialGateway with MySensors: **
Sketch uses 17,566 bytes (57%) of program storage space. Maximum is 30,720 bytes.
Global variables use 688 bytes (33%) of dynamic memory, leaving 1,360 bytes for local variables. Maximum is 2,048 bytes.SerialGateway with RadioHead:
Sketch uses 22,242 bytes (72%) of program storage space. Maximum is 30,720 bytes.
Global variables use 1,455 bytes (71%) of dynamic memory, leaving 593 bytes for local variables. Maximum is 2,048 bytes.**DallasTemp with MySensors: **
Sketch uses 20,288 bytes (66%) of program storage space. Maximum is 30,720 bytes.
Global variables use 551 bytes (26%) of dynamic memory, leaving 1,497 bytes for local variables. Maximum is 2,048 bytes.DallasTemp with RadioHead:
Sketch uses 24,592 bytes (80%) of program storage space. Maximum is 30,720 bytes.
Global variables use 1,319 bytes (64%) of dynamic memory, leaving 729 bytes for local variables. Maximum is 2,048 bytes.@ToSa said:
SerialGateway with RadioHead:
Sketch uses 22,242 bytes (72%) of program storage space. Maximum is 30,720 bytes.
Global variables use 1,455 bytes (71%) of dynamic memory, leaving 593 bytes for local variables. Maximum is 2,048 bytes.What radio/Arduino IDE did you compile for?
For Serial Gateway, nrf24, Arduino 1.5.7 I get:
Sketch uses 20.962 bytes (64%) of program storage space. Maximum is 32.256 bytes.
Global variables use 1.471 bytes (71%) of dynamic memory, leaving 577 bytes for local variables. Maximum is 2.048 bytes.Wonder what the runtime values are...
Currently MySensor::setRadio creates an instance of RHMesh at runtime, so RAM usage is even worse...
http://yveaux.blogspot.nl
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@ToSa said:
SerialGateway with RadioHead:
Sketch uses 22,242 bytes (72%) of program storage space. Maximum is 30,720 bytes.
Global variables use 1,455 bytes (71%) of dynamic memory, leaving 593 bytes for local variables. Maximum is 2,048 bytes.What radio/Arduino IDE did you compile for?
For Serial Gateway, nrf24, Arduino 1.5.7 I get:
Sketch uses 20.962 bytes (64%) of program storage space. Maximum is 32.256 bytes.
Global variables use 1.471 bytes (71%) of dynamic memory, leaving 577 bytes for local variables. Maximum is 2.048 bytes.Wonder what the runtime values are...
Currently MySensor::setRadio creates an instance of RHMesh at runtime, so RAM usage is even worse...
This post is deleted! -
@ToSa said:
SerialGateway with RadioHead:
Sketch uses 22,242 bytes (72%) of program storage space. Maximum is 30,720 bytes.
Global variables use 1,455 bytes (71%) of dynamic memory, leaving 593 bytes for local variables. Maximum is 2,048 bytes.What radio/Arduino IDE did you compile for?
For Serial Gateway, nrf24, Arduino 1.5.7 I get:
Sketch uses 20.962 bytes (64%) of program storage space. Maximum is 32.256 bytes.
Global variables use 1.471 bytes (71%) of dynamic memory, leaving 577 bytes for local variables. Maximum is 2.048 bytes.Wonder what the runtime values are...
Currently MySensor::setRadio creates an instance of RHMesh at runtime, so RAM usage is even worse...
@Yveaux said:
What radio/Arduino IDE did you compile for?
nRF24 / 1.5.6-r2
DEBUG turned on - your values appear to be with DEBUG turned offI did a few changes starting to reduce the header so I can't rerun with DEBUG off and compare right now...
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A small digression from the main topic here, but I just tested the mesh functionality of the library. I took a laptop with a serial gateway outside of the range of my sensor and observed that it stopped working. I then went back a few metres and powered up a battery powered sensor which basically just sent hello every second and processed messages. I was able to significantly extend my range, experiencing only a few seconds of interrupt in the ping flow.
Moving back and powering down the intermediate node, the direct route was reestablished within a new couple of seconds and everything was working correctly again :-) I think I will have much fun playing with this.
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A small digression from the main topic here, but I just tested the mesh functionality of the library. I took a laptop with a serial gateway outside of the range of my sensor and observed that it stopped working. I then went back a few metres and powered up a battery powered sensor which basically just sent hello every second and processed messages. I was able to significantly extend my range, experiencing only a few seconds of interrupt in the ping flow.
Moving back and powering down the intermediate node, the direct route was reestablished within a new couple of seconds and everything was working correctly again :-) I think I will have much fun playing with this.
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@kolaf I totally agree with you.
The MySensors library currently has a solid nrf24 implementation and routing works fine (though not fully mesh) so there's no direct need to switch driver and routing layer.
This is a roadmap item on which we should continue working, IMO together with the RadioHead development. The RadioHead library has only recently been developed (few months old or so) and is already very mature looking. This is very promising for the future and there's no use in developing/maintaining 2 nearly identical libraries.
I think the current flaws (e.g. code & message size) can be improved with our help making it a solid base for MySensors.@Yveaux said:
The MySensors library currently has a solid nrf24 implementation and routing works fine (though not fully mesh) so there's no direct need to switch driver and routing layer.
What are the differences between the MySensors protocol and RH in terms of mesh dynamics?
I'm guessing that RH is more dynamicly configured, but I'd like to understand more.
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You are most certainly correct, I have edited my original post. I'm suffering a bit from tendinitis, so I'm using speech recognition when I write. Sometimes it recognises almost exactly what I say ;)
@kolaf ah, great to see your results then!
I read some mixed results on the Radiohead mailing list regarding mesh, so good to see it's working for you.
BTW I'm in the progress of writing wireshark directors for Radiohead which can be used with the nrf24 sniffer. It'll give us better insight on Radiohead's performance and functioning. -
It makes sense to migrate the MySensors last,sender and destination bytes to RH from,source,dest.
I do not think it makes sense to move type (V_code) or command into the RH FLAGs. Typically when such space is reserved for the protocol in the header but not yet fully used, it's subject to change as the protocal evolves. If part of the goal is to take advantage of the maintenance and ongoing development of RH, we don't want to set up a conflict - because other users are not going to use those FLAGs our way anyway.
Basically, Radio Head should be concerned with delivering a payload (set of bytes) to a node. Everything specific to just the MySensors application should be in the payload (as seen by RH). That includes:
- child id ("sensor")
- command
- V_code ("type")
- version (if needed)
- ack - is this still needed??
If we want to remain compatible with other RH users (ie: their development), rather than re-allocating bytes or bits in the RH header to our own purposes, we would be putting our MySensors' header in the RH payload, but omitting from our header the redundant fields which are handled by RH:
- last,
- sender,
- destination
The RH payload would include the reduced MySensors header plus the MySensors payload.
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It makes sense to migrate the MySensors last,sender and destination bytes to RH from,source,dest.
I do not think it makes sense to move type (V_code) or command into the RH FLAGs. Typically when such space is reserved for the protocol in the header but not yet fully used, it's subject to change as the protocal evolves. If part of the goal is to take advantage of the maintenance and ongoing development of RH, we don't want to set up a conflict - because other users are not going to use those FLAGs our way anyway.
Basically, Radio Head should be concerned with delivering a payload (set of bytes) to a node. Everything specific to just the MySensors application should be in the payload (as seen by RH). That includes:
- child id ("sensor")
- command
- V_code ("type")
- version (if needed)
- ack - is this still needed??
If we want to remain compatible with other RH users (ie: their development), rather than re-allocating bytes or bits in the RH header to our own purposes, we would be putting our MySensors' header in the RH payload, but omitting from our header the redundant fields which are handled by RH:
- last,
- sender,
- destination
The RH payload would include the reduced MySensors header plus the MySensors payload.
@Zeph said:
I do not think it makes sense to move type (V_code) or command into the RH FLAGs. Typically when such space is reserved for the protocol in the header but not yet fully used, it's subject to change as the protocal evolves. If part of the goal is to take advantage of the maintenance and ongoing development of RH, we don't want to set up a conflict - because other users are not going to use those FLAGs our way anyway.
From the RH documentation / the source code:
- for Datagram FLAGS:
A bitmask of flags. The most significant 4 bits are reserved for use by RadioHead. The least significant 4 bits are reserved for applications. - for Router/Mesh FLAGS:
Optional flags for use by subclasses or application layer
Not setting up a conflict with the RH code will be the biggest issue: the two benefits of RH are the multi radio support and the more advanced Mesh topology - which would be worth a couple of additional bytes in flash and ram - but the other reason for the big overhead is that several advanced features of the nRF24 chip are not used because they are not available in all supported chips.
Two examples:
- the multi-pipe capability of nRF24 would allow to filter traffic to only current address and broadcast and avoid that any other traffic ever reaches the MCU (only slightly less code but wondering if that helps with battery powered nodes).
- the ReliableDiagram processing in code essentially duplicates capabilities that are build into the chipset as well (auto-acknowledge / autoresubmit)
I know you are interested in getting RF69 supported but the question is how much negative impact for all the other users (with current nRF24 setup) is acceptable. That's like using the RF69 and implementing an AES encryption in code rather than using the build-in capabilities of the chip...
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Didn't want to sound too negative yesterday...
- I'm still looking at the RH library but changes will be major and will not necessarily be in line with the RH purpose so Mike might not want to merge them into the main codebase: mainly defining what driver is used at compile time of the library (similar to MyConfig) which would then allow to e.g. "bypass" the majority of ReliableDatagram etc.
- what we should definitely do is splitting application layer and network layer: no longer inherit MySensor from RF24 but create an RF24 instance at runtime / leave application layer message handling in MySensors / move network layer message handling to a separate class (the "driver" for RF24). This will make it way easier to switch radios in the future.
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Didn't want to sound too negative yesterday...
- I'm still looking at the RH library but changes will be major and will not necessarily be in line with the RH purpose so Mike might not want to merge them into the main codebase: mainly defining what driver is used at compile time of the library (similar to MyConfig) which would then allow to e.g. "bypass" the majority of ReliableDatagram etc.
- what we should definitely do is splitting application layer and network layer: no longer inherit MySensor from RF24 but create an RF24 instance at runtime / leave application layer message handling in MySensors / move network layer message handling to a separate class (the "driver" for RF24). This will make it way easier to switch radios in the future.
@ToSa said:
Didn't want to sound too negative yesterday...
- I'm still looking at the RH library but changes will be major and will not necessarily be in line with the RH purpose so Mike might not want to merge them into the main codebase: mainly defining what driver is used at compile time of the library (similar to MyConfig) which would then allow to e.g. "bypass" the majority of ReliableDatagram etc.
Is it not sufficient that we define the radio at compile time in the sensors and the gateway as we have done now?
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@ToSa said:
Didn't want to sound too negative yesterday...
- I'm still looking at the RH library but changes will be major and will not necessarily be in line with the RH purpose so Mike might not want to merge them into the main codebase: mainly defining what driver is used at compile time of the library (similar to MyConfig) which would then allow to e.g. "bypass" the majority of ReliableDatagram etc.
Is it not sufficient that we define the radio at compile time in the sensors and the gateway as we have done now?
@kolaf said:
Is it not sufficient that we define the radio at compile time in the sensors and the gateway as we have done now?
I'm talking about changing how the library is compiled and essentially having a separate ReliableDiagram class that bypasses manual handling of ACKs etc. and instead leaves reliable delivery to the radio itself. Mesh and Router are derived from the ReliableDatagram class - therefore we would need to define which radio to use prior to library compilation - not just prior to sketch compilation.
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@Zeph said:
I do not think it makes sense to move type (V_code) or command into the RH FLAGs. Typically when such space is reserved for the protocol in the header but not yet fully used, it's subject to change as the protocal evolves. If part of the goal is to take advantage of the maintenance and ongoing development of RH, we don't want to set up a conflict - because other users are not going to use those FLAGs our way anyway.
From the RH documentation / the source code:
- for Datagram FLAGS:
A bitmask of flags. The most significant 4 bits are reserved for use by RadioHead. The least significant 4 bits are reserved for applications. - for Router/Mesh FLAGS:
Optional flags for use by subclasses or application layer
Not setting up a conflict with the RH code will be the biggest issue: the two benefits of RH are the multi radio support and the more advanced Mesh topology - which would be worth a couple of additional bytes in flash and ram - but the other reason for the big overhead is that several advanced features of the nRF24 chip are not used because they are not available in all supported chips.
Two examples:
- the multi-pipe capability of nRF24 would allow to filter traffic to only current address and broadcast and avoid that any other traffic ever reaches the MCU (only slightly less code but wondering if that helps with battery powered nodes).
- the ReliableDiagram processing in code essentially duplicates capabilities that are build into the chipset as well (auto-acknowledge / autoresubmit)
I know you are interested in getting RF69 supported but the question is how much negative impact for all the other users (with current nRF24 setup) is acceptable. That's like using the RF69 and implementing an AES encryption in code rather than using the build-in capabilities of the chip...
- for Datagram FLAGS:
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@ToSa said:
the two benefits of RH are the multi radio support and the more advanced Mesh topology
Could someone summarize the differences between the current MySensors mesh and the RadioHead mesh, and why the latter is preferable for us?
RH is a true mesh where every node can communicate with any other directly (if in range). All nodes acts as repeaters.
MySensors forms nodes forms a star network where every node has a parent and potentially a few child sensors. The gateway node is the "center". Every node always tries to find the closest (least number of hops) route to gateway.
GW / \ A D / \ B CIf B want to communicate with C messages has to pass A in the MySensors case. In RH C and B will communicate directly if the can hear each other.
RH does not use the nifty features NRF24L01 offers which offloads mcu (pipes/addresses) nor auto ack (impossible in RH setup). So nodes in range has to process every message it can "hear". And this can potentially be a lot.
