A few questions for my project

[David Jimenez]

Hi to All !!

First Thanks to Fernando for his great job

I will start slowly start my own Ferduino, I'll be adding components go when I have money.
So I want to make sure what I need, I've been reading the forum for several days and I still have questions

1. What is the function of RFM12B? It is completely necessary?

2. My idea is to put 2 shields of relays, one with 8 relays 2A and another with 8 relays 10A. I need 1 PCF8575 + 2 ULN2B03 ?? Could explain how this works?

3. Formerly had a Duemilanove based controller and was introduced a LED with a resistance in the circuit to improve the accuracy DS1307, is this necessary?

4. What is the difference between these two schemes? which would be better?

That's all for now ... But sure I'll have to check more things


Thanks in advance

Best regards

[Fernando Garcia]

Hi!

Welcome David!

To post images use "Image-URL" instead "Image BBCode".

1 - RFM12B is a wireless transceiver isn't essential.

2 - The IC (Integrated Circuit) is ULN2803. Is needed if your relay board is active low it mean LOW to turn ON and HIGH to turn OFF.

The wiring:

3 - I have no idea about it. The imprecision is acceptable for me are 1 or 2 minutes per month.

4 - The ULN have transistor and diodes inside it turns the circuit more simple.

Best regards.

[David Jimenez]

Thanks a lot Fernando !!

I understand then that should add first PCF8575 to multiply outputs and then ULN2803 behind only if necessary, I guess it would be one for each shield of relays ??

Fans would use each output of ULN2003A? Or all with serial connection ??

Thanks for all

Best regards

[Fernando Garcia]

Yes, 1 IC to each board.

1 pin to each fan.

[David Jimenez]

Hello friends !!

more questions ...

The resistors used in most schemes, tft shield, level control etc .. are 0.25W (1/4 w) and 5% ??
I have part of the components (DS 1307 crystal oscilator ...), and little money, so I thought myself making the "tft shield"
In this case when not using the "tft shield" of itead, the RTC pins go directly to pins 18 and 19 ?? to do any changes in the code for it ??

Thanks a lot

David

-------------------------------- Last edited Thu Mar 26, 2015 7:21 pm --------------------------------

David Jimenez » 8 minutes ago wrote:

In this case when not using the "tft shield" of itead, the RTC pins go directly to pins 18 and 19 ?? to do any changes in the code for it ??

Thanks a lot

David

Ok !! sorry for the question I´ve see this post

Thanks

[Fernando Garcia]

Hi!

1/4 W is enough.

Best regards.

[David Jimenez]

OK !! Thanks !!

Other questions... If I´ve to use only 10 relays and not use ph and other stamps. I need the PCF8575 ?? I do not understand very well what their function
I see the moon ligth used the pin 44 , but.. how it works ? Using a relay to turn on or off ? Or is dimmed ? Do not see a dimming channel in the scheme for her

A lot of thanks once again

Best wishes
David

[Fernando Garcia]

Hi!

Check here what pins you will use.

Only Arduino pins should be enough. You can change the pins to some devices like multiplexer and Serial3 (pins 14, 15, 16 and 17) then use to others functions.

The circuit for moonlight is equal to daylight.

Best regards.