Opentherm Gateway

[wouterbaake]

I am trying to do a similar thing with the OTgateway, leaving out the MAX232, but interfacing the TTL directly to the UART of my raspberry PI. Because it seems a bit stupid to use 2 MAX232's to have them talk to each other.
However, so far no luck...

I've checked with an FTDI USB cable that the OTgateway is working.
Also, I connected two resistors to reduce the 5V output to 3.3V so I don't blow up the raspberry's UART. The RX on the 16F88 is directly connected to the Raspberry.
When I monitor the voltage I see slight fluctuations, which is probably the OTgateway generating a signal.
Unfortunately, I haven't been able to get a signal from the raspberry UART. I know that the TX from the raspberry is 3V3, but this should be detected as logical high by the 16F88 if I am correct.

Does anyone have any tips that I could try?

[hvxl]

When RB2 is configured as a serial input, the signal goes through a schmitt trigger that needs a level of over 4V to toggle to logical 1. So, probably the PIC sees a constant 0 which it interprets as a BREAK signal that prevents normal operation.

I suggest you start by tying RB2 to 5V. You should then at least be able to receive the reports the gateway generates on your RPi. If that works, start thinking about a converter for the data from the RPi to the gateway.

On the other hand, the PIC can run on 3V3 as well. So that's another possibility: Replace IC3 by a 3.3V version. Although you will probably need some more circuitry/code changes to make that work.

[Digit]

Another option could be to connect a EZL70 (http://www.eztcp.com/en/products/ezl-70.php) to either the PIC or RS232 output.
That way you won't even need the RPi nearby. (Yeah, I know, the EZL70 is probably just as expensive as the RPi )

[vanisher]

Would it be possible to implement the "Openhaard" mode on the iSense?

[Bwired]

Another option could be to connect a EZL70 (http://www.eztcp.com/en/products/ezl-70.php) to either the PIC or RS232 output.
That way you won't even need the RPi nearby. (Yeah, I know, the EZL70 is probably just as expensive as the RPi )

im building this one right now, connected to the Pic.

[Rutger]

Is there a perfect place for the gateway? Can I use a 'kroonsteentje' between the connection on the loft (zolder), were the cable from my iSense is visble and goes into my CV and a new wire will go to a room on the 2ndfloor were my pc+gateway is?
Is there a max length of 2-wire cable I can you use with this gateway, because I don''t want to split the wires on my iSense and use some cablestrips on the wall.

[jeroenc]

Hello,

I've just soldered my board.
While testing it with Putty via an RS232-USB converter it says after startup "opentherm gateway 3.1" or something but then goes into an infinite loop with "SE".
Anybody any ideas what could be wrong, or how to debug (no in system debugging?)?

Tnx!

[Digit]

Are you sending something to the Gateway? SE stands for Syntax Error, which is a response to a command received by the Gateway and which was wrong or incomplete. See http://www.tclcode.com/opentherm/firmwa ... figuration

[vossie]

Rutger, I don't know the maximum length of cable between your boiler and thermostat but
you can also hook up the gateway at the atic where you can see the cable going in to the boiler, than you can use a long serial cable between the gateway and computer.
The serial cable can be 150 meter max

[blb]

From OT protocol V2-2 spec:
cable:twisted OR even untwisted 2 wire pair
Distance: max. 50 meters
Cable resistance: max 2 x 5 Ohms
Polarity: polarity free

[jeroenc]

Check here guys: http://domoticaforum.eu/viewtopic.php?f ... 8&start=75

[jeroenc]

Are you sending something to the Gateway? SE stands for Syntax Error, which is a response to a command received by the Gateway and which was wrong or incomplete. See http://www.tclcode.com/opentherm/firmwa ... figuration

Hi Digit, tnx for your reply.

I was aware SE meant Syntax Error but I'm not sending anytinhg, that's the weird part.
Any thoughts? I can't debug with the PIC in-system or can I?

Regards, jeroen

[Digit]

Sorry, no more hints or tips... haven't seen this behavior myself.

[wouterbaake]

You wrote that you use putty to connect to the serial port. I think that putty (as a telnet/ssh client) will send something on the serial port, to which the gateway responds with SE. Try using cat (on linux) or some other program that just listens on the port instead of sending.

[jeroenc]

Hi WB,
Tnx for your answer.

Unfortunately I have the same problem when using the OpenthermMonitor software, which was specifically written for the gateway.
My Linux knowledge is zero, do you have any other Windows alternatives?

Ps: I was using Putty in Serial mode, not telnet.

Maybe the problem lies in the serial-usb cable, I will look for different drivers.

Best regards, Jeroen