Relay8 Esp8826 12-E I2C connection.

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cescoferraro
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Relay8 Esp8826 12-E I2C connection.

Post by cescoferraro » Fri Sep 04, 2015 3:35 pm

I love being able to use the relay 8 with an arduino. But the lack of Wi-fi, or the $$ and unreliability of wifi makes me think twice before starting another project.
Lately I have discovered this little cheap and reliable MCU with Wi-Fi. https://github.com/nodemcu/nodemcu-devkit-v1.0
But the best thing is that I can use Arduino c++ syntax and libraries. Thanks to this https://github.com/esp8266/Arduino

SO the first thing that comes on my mind is to plug it with the relay8 shield.
But the MCU operates at 3.3V and I am not sure about the shield.
As of mounted on top of the arduino I am sure it uses 5V logic.
But the I2C chip's datasheet http://ww1.ds/en/DeviceDoc/21952b.pdf says it CAN operate at 3.3V.

I got a logic level converter that I planning to use as described in this photo http://msx-elektronika.pl/photo/connect1.png
I have not tested it yet. But cannot find a reason not to work. Any advice?

Have also wondered if I could plug those without the logic converter. Considering that on both situation I am using an external input to supply power to the shield (No jumper on). Any pointers?

Appreciate your help!
PS: The relay8 deserves a section

andrew
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Re: Relay8 Esp8826 12-E I2C connection.

Post by andrew » Sat Sep 05, 2015 5:01 am

Make sure you have separate relay power (option 1 in http://www.freetronics.com.au/pages/rel ... tart-guide). Otherwise running the MCP23017 will be fine at 3.3V, you may want to test it before connecting any relay coils (or relay power) - the LEDs for each MOSFET will indicate the output status.

cescoferraro
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Re: Relay8 Esp8826 12-E I2C connection.

Post by cescoferraro » Tue Sep 08, 2015 9:57 pm

Yeah!! I did it.
Had to connect SDL, SCL for I2C accordingly. 3V3 from the board to the shield 5V pin(the shield did not show any sign of track comming/going from the 3V3 pin, for security reasons I suppose). GND to GND and RST to RST.

Are there any implication of operating the shield at 3V3?
Do I loose power in any way? Do I still get the 115mA on each channel?
I intend to run multiple shields with different relay voltage

angusgr
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Re: Relay8 Esp8826 12-E I2C connection.

Post by angusgr » Tue Sep 08, 2015 11:56 pm

Glad you got it working, nicely done!

The Arduino Shield "R3" model uses the "IORef" pin to provide the I/O voltage for the shield. The board provides 5V here if it uses 5V I/O, and 3.3V if it uses 3.3V I/O.

If your Relay8 shield is V2.0 or newer and has an IORef pin on the shield then this is the pin you'll need to connect. You can supply 3.3V to this pin, and leave the 5V pin disconnected, and your shield should work perfectly with the ESP.

To put it another way, the connections you need are: 3.3V to IORef, GND, SDA, SCL, RST (if you want a reset button).

If your shield is pre-V2.0 then it takes power from the 5V pin and it will probably "just work" if you feed 3.3V to this pin instead, but we don't support it on the older version.


Angus

cescoferraro
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Re: Relay8 Esp8826 12-E I2C connection.

Post by cescoferraro » Wed Sep 09, 2015 8:54 pm

I pretty sure I have the v1.0, at least that is what is says underneath it.
Which is weird because I bought the last batch ~2 months ago and cannot see any reference of a V2.0 version around the e commerce.
There is a IOREF hole on my, but cant see any tracks. How do I get one of those?

At least on my tests, the relay shield without the RST connected would barely work. On my setup seems very stable so far.
I am supplying 5v to the board and 3v3 to the chip, so far I got the the full 2Amps from the SSR I got to test with.
I was hoping to be able to use 12V as well, but have not tested. Should not I?

cescoferraro
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Re: Relay8 Esp8826 12-E I2C connection.

Post by cescoferraro » Sun Oct 04, 2015 2:39 pm

How do I get a relay shield v2.0??

angusgr
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Re: Relay8 Esp8826 12-E I2C connection.

Post by angusgr » Mon Oct 05, 2015 2:34 am

We're shipping Relay8 v2.0 now. The website still shows the old model shield (it'll be updated soon), but if you order you'll get the new one.

You should be OK using v1.0 in the way you're using it now, though.

cescoferraro
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Re: Relay8 Esp8826 12-E I2C connection.

Post by cescoferraro » Thu Feb 04, 2016 12:10 am

I still see the v1.0 on the ecommerce though

andrew
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Re: Relay8 Esp8826 12-E I2C connection.

Post by andrew » Thu Feb 04, 2016 1:35 am

We will update the photos when new stock arrives (around two to three weeks).

cescoferraro
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Re: Relay8 Esp8826 12-E I2C connection.

Post by cescoferraro » Tue May 17, 2016 10:34 am

Nothing yet?
I want to ask why is 115mA the max current output? What limits it? Is it the mpc?
I have been seeing lots of 12v 1A dc LED bulbs everywhere. It would be nice if the relay could fire those.

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