RS485/RS232/Serial transport class for mysensors.org

[TimO]

So, I've tried to further invest the problem and there is something wrong with _dev.write() in transportSend(). It is too much C-Kungfu for me but there is something wrong with the conversion of data.

• _dev.write("bla") looks good in terminal
• _dev.write(to) throws trash in the terminal
• Serial.println(to) looks good in terminal

Here is the output of the soft-serial:

#��
�X��z
               �Humidity Sensor�
�X
��
     �1.0
�X��b
�X��
b
�X
                                     ��*�
�����
�X
                                                     ��*�
gfB

�X
                                                                    ��*�
�����
�X
    ��*�
gfB

�X
                   

Another thing:

The management of the DE-Pin is missing right?

[hek]

to is a uint_t...so I guess it could generate trash in the terminal when showing the low ASCII values. Guess you'd have to use some other program to view the bytes sent.

Yes, de-pin was stripped away. Would it be useful in your setup?

(thankful for your help out testing it... I need some more time before I can setup a test rig)

[TimO]

Holy crap ...
It was too obvious. :-(

Gateway can't work with this code:
https://github.com/mysensors/Arduino/blob/development/libraries/MySensors/examples/GatewaySerialRS485/GatewaySerialRS485.ino

#define MY_DEFAULT_ERR_LED_PIN 7  // Error led pin
#define MY_DEFAULT_RX_LED_PIN  8  // Receive led pin
#define MY_DEFAULT_TX_LED_PIN  9  // the PCB, on board LED

@hek: Your code works!

The de-pin is set to high if a node wants to send something, otherwise it is set to ground.
I'll try to add that code.

[hek]

@TimO

:blush: I Sorry.. should have changed those pin assignments of course... I'll push an update ASAP.

[LeoDesigner]

@hek
I am wondering why did you remove the code responsible for dePin management ?
It's not possible to use MAX485 boards without tx/rx management.

[TimO]

@LeoDesigner : yeah, you're right, that is needed.

But there seems to be another problem, I can't get the current development code to work. I've simply interconnected two Nanos at D8/D9. The gateway and the motion example come up fine according to serial output and the motion sensor definiatly sends something via AltSerial but the gateway doesn't seem to recognize it.

A simple test, where I pipe the input on hardware serial of one nano to AltSerial on the second nano and from there to hardware serial works just fine, so hardware and AltSerial is working.

Sender:

#include <AltSoftSerial.h>

AltSoftSerial altSerial;

void setup() {
  Serial.begin(115200);
  Serial.println("Demo begins");

  altSerial.begin(115200);

}

void loop() {
  char c;

  if (Serial.available()) {
    c = Serial.read();
    altSerial.print(c);
  }

}

Receiver:

#include <AltSoftSerial.h>

AltSoftSerial altSerial;

void setup() {
  Serial.begin(115200);
  Serial.println("Demo begins");

  altSerial.begin(115200);

}

void loop() {
  char c;

  if (altSerial.available()) {
    c = altSerial.read();
    Serial.print(c);
  }

}

[hek]

Added DE-pin management

https://github.com/mysensors/Arduino/pull/266

[shabba]

I am very interested in doing this as I have many sensors local to my gateway. I use domoticz and see from http://www.domoticz.com/forum/viewtopic.php?f=6&t=8018 that people are doing this. I was just wondering would this do as a USB adaptor? Seems very cheap :

http://www.aliexpress.com/item/1-pcs-USB-to-RS485-USB-485-Converter-Adapter-Support-Win7-XP-Vista-Linux-for-Mac/1684582905.html?spm=2114.031010208.3.1.hHoz94&ws_ab_test=searchweb201556_10_79_78_77_80_61,searchweb201644_0,searchweb201560_9

Also was looking at :
http://www.aliexpress.com/item/FREE-SHIPPING-5PCS-LOT-MAX485-module-RS485-module-TTL-turn-RS-485-module-MCU-development-accessories/1718665649.html

Appreciate any feedback.

Thanks.

[MarkV]

@LeoDesigner

I'm searching for a usb transport class, could i use this??

I'd like to connect my arduino (with sensors/actuators connected to it) to my rasberrypi through usb, without the wireless part, but still see them as mysensors sensors.

Is this possible or could someone make a transport class for it???

[LeoDesigner]

@MarkV
Regarding the USB to RS485 adapters:
I think they are using a some kind of serial to USB chip like CH340/341. So your RPi will be able to see RS485 bus as the regular serial port. It may work. It worth trying, you can always build an Ethernet GW later in other case.

@shabba
I am using exactly the same MAX485 modules. It is much more reliable media comparing to radio communication.

@hek
Thanks for adding DE pin management code.

[scalz]

hi.

I am not sure if it can be useful.. I have read this note recently, about rs485 powering chip (3.3v or 5v). And I found this interesting, for knowledge..
https://e2e.ti.com/support/interface/industrial_interface/f/142/t/93260
So what I understand here, and it makes sense, is that : even if some rs485 chips are able to be powered with 3.3v or 5v, if you want to power it with 3.3v, it can work of course with a 5v chip, but it is better to use a true 3.3v chip only. Because they are more sensitive to be rs485 compliant (better internal transistor).

Always good to know :smiley:

[anti]

@TimO I cloned the current development branch, and tried to use a modified motion sketch, and a gateway sketch, simply interconnecting two mini-pros with TTL serial : the same problem appears.

I can only see garbage sent on the AltSerial pins, so the gateway don't see the message.

Before I dig more and start debugging, did anybody made progress on that problem ?

[TimO]

@anti: I'm glad, I'm not the only one! :-)
I've tried to find the problem, but had no luck.

What is bugging me: it was working with a early version, before it was merged into development, but I don't see any changes.

I've not tested the latest / current version though.

[andriej]

Hi!

Glad to see 'wired' version of MySensor protocol coming.
One question - how long wires and how many sensors on one pair/multiple pairs will be supported?

I'm thinking about cabling for new home, which means many meters of cable to every sensor/door/actuator/ligth/meter etc.

In best scenario - one cat5e - one termination (sensor/node/etc.)
Currently I'm looking for a cabled version of protocol to support it and be 101% stable (no hiccups and freezes over the protocol), so I can rely on my home.

MySensors seems to be great to implement, but I'm worried about the signal... I was thinking about letting something around 12-24-30V thru one pair of Cat5 to power all nodes from one power-source (with backup batteries).

Or - are there any better alternatives for RS485, that doesn't need resistors, have no limitations of 32 devices etc?

[LeoDesigner]

@andriej
According to: https://en.wikipedia.org/wiki/RS-485
"It offers data transmission speeds of 35 Mbit/s up to 10 m and 100 kbit/s at 1200 m. "
also check this: https://www.maximintegrated.com/en/app-notes/index.mvp/id/367
You may design a bus with up to 256 nodes.
CAT5 is the best choice anyway for any type of communication (I mean you can run regular Ethernet on them too).
Check the video at the beginning of the post. It's a working example of two remote nodes connected only with one CAT5 cable over 50m. They are working at 115200 - however speed might be up to 1 Mbit/s.

[andriej]

@LeoDesigner but how would I connect all sensors in house and relays too?
SOme resistors needed? Star topology? Few gateways?

[LeoDesigner]

@andriej
The star topology could be a problem. However for low speed nodes this may work anyway.
You may need something like RS485 hub :) or a GW with many RS485 bus ports.
Or just a separate MAX485 board for each node. You need to test it.

[anti]

@TimO Well... it turns out that the garbage seen on the wire was not garbage, just the binary serial protocol. And the node was desperately attempting to find a parent, with no success.

FYI this is how I workaround it. But I did not feel like I could fix it for 100% sure.

The gateway ignored the broadcasts from the node. The following code in MyTransportRS485 triggered for probably wrong reasons (sender=0; nodeid=0;station=broadcast) :

               if ((_recSender == _nodeId) ||
                  (_recStation != _nodeId &&
                   _recStation != BROADCAST_ADDRESS)) {
                          _dev.print(" wrongid: ");

Since the gateway was not responding correctly to the node broadcasts, I solved the serial communication problem between node and gateway by defining a fixed node Id :

#define MY_NODE_ID 10

(ps: the MySensors version used was cloned from git today)

[anti]

Replying to myself... Of course the "Controller" MUST be properly connected
for dynamic nodes IDs to function properly, since it's the controller's job to affect the node ids.

This explains a part of my original problem.

[kimot]

I think, that CAN transceiver chip is better then RS485 transceiver chip.
Then we dont need direction setting pin and bus state is better determined, becose CAn bus is prepered for bus collisions, RS485 not.
I mean only CAN bus transceiver, not CAN controller ! For example MCP2551 or MCP2562.
And we can use normal serial library.