ARDUINO am KNX

[sx3]

Perfect, I ordered the parts needed, just sit down and wait now.

[tuxedo]

Exactly. That's it. Very easy, very reliable. The only downside: adum1201 is "very tiny". So take your time when soldering the SO8 package. For experimenting on breadboard: Check out ebay. There are SO8 adapter PCBs available.

[sx3]

alright, no need of resistors or something like using optocouplers?, just connect Tx to encode and Rx to decode and, VCC+GND on each side and look happy I guess?

[tuxedo]

The best way to have a galvanic separation between bcu and arduino: Use ADUM1201 chip (http://www.analog.com/media/en/techn...M1200_1201.pdf). Works like a charm.

[sx3]

I understand.
But I was thinking weither the schematic that was posted earlier, would apply as a galvanic separation between the Arduino <-> KNX aswell.
Because that schematic lookes like it inverts the signals. I don't know if that would make in difference, because I'm not that good at electronic.
But given that I have earlier connected a Pro Mini to the KNX without optocouplers, probably using none-inverted signal I thought that schematic won't work as galvanic separation between the MEGA and the KNX.

Because I will power the MEGA from external power supply, I would want to galvanic separate both the KNX and the third party device from the Arduino external power supply.
Ofcourse I will use separate HW serial/UART, hence using the MEGA.

[tuxedo]

Do you still think it would work with Arduino->KNX?

The connection between your arduino and your third-party-device is totally independant from the arduino<->knx connection.

You are free to adapt the arduino uart that is used to communicate with your third-party device as needed. Keep in mind, that you use two independant uarts.. one for knx with BCU and and for your third-party device which uses different logic levels.

[sx3]

Thanks, but that optocircuit is "inverted" and intended for CMOS 4000 TTL signals. Rego600 have one signal 3V3 and second 5V; one signal is inverted and
second not.

I'm not sure that either Arduino or the Siemens BCU is using this type of TTL's
As you can see on that schematic, the circuit is different on each side of the optocoupler.
Do you still think it would work with Arduino->KNX?

[Eugenius]

Alright, I might consider the Zero for final version.
For now, I Think I go for the Mega, If someone could help me out with schematic/diagram between Ardu-serial and KNX-uart using MCT6 or ILD2, I would be very glad.

Example:
http://rago600.sourceforge.net/generic_com.pdf

[sx3]

Alright, I might consider the Zero for final version.
For now, I Think I go for the Mega, If someone could help me out with schematic/diagram between Ardu-serial and KNX-uart using MCT6 or ILD2, I would be very glad.

[tuxedo]

Info about the serials came from samd21 datasheet + google.

I have no exact power consumption. But our KONNEKTING team mate Masifi is already using the SAMD21 direclty on KNX (but with self assembled NCN5120 KNX Transceiver instead of Siemens BCU).

[sx3]

Hmm, maybe the Zero is interesting after all.. Where did you find info on the serials? I didn't manage to find it when I looked up the boards Before.
How many mA will the Zero draw from the KNX Power supply?

[tuxedo]

The Zero has

Flash Memory	256 KB
SRAM	32 KB

That's more than you need. Regarding multiple serial ports, read --> https://learn.adafruit.com/using-ats...ports?view=all

For testing/Programming the Zero has a dedictated debugger port. With that (and Atmel Studio) you can step line-by-line through your code. That's far better than serial console debugging.

[sx3]

It's because of the serial ports. The arduino will be a gateway between my heat pump and KNX. Hence 2 HW serial needed + 1 extra to monitor, during testing and programming.
Plus I wasn't sure if the Zero memory would have been sufficent to build this gateway.

[tuxedo]

Question is: Why do you want to use the mega? Isn't any other arduino sufficient? Or is it just about the 2nd serialport?
How about Arduino Zero? --> https://www.arduino.cc/en/Main/ArduinoBoardZero

MOre powerful, more energie efficient and can be powered via BCU.

[sx3]

Thanks mate! You did use resistors right? what size, and to which pin?
Do you perhaps have a schematic for the connection?