Using Relay Module With BBB

[colone...@gmail.com]

Hello,
I'm trying to use relay module with beaglebone black.
I bought relay module from china.
It is very similar to this: http://www.hobbyist.co.nz/sites/default/files/8ChannelRelay_small%20%28Custom%29.jpg
I have connected VCC to BBB's VDD_5V(P9_05) and GND to BBB's DGNG(P9_01).
Here is the problem:
When I connect any gpio port to relay module's any signal pin, relay is starting to work.
Even GPIO is high or low I can't switch off the relay. So I can't control any relay from BBB.
What can I do to solve this problem?
Many thanks.
Note: I tried relay module with external power source but results are same.

[Gerald Coley]

I can't tell much from a picture. Doe sit have a schematic, or a link to one?

If the relays are 5V, then you cannot drive them from a GPIO as it is 3.3V and delivers only about 6mA.. Connecting 5V will blow the processor. You would need  a level shifter such as a transistor to drive the relay..

Gerald

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[colone...@gmail.com]

http://www.wlelectronix.com/Content/Images/uploaded/Relay%208%20Way_2.png
My relay module is must be something like this.
Relays are 5v, so i use VDD_5V(P9_05) to drive them. GPIO turns on and off them in normal. But there is a problem in my situation. I'm trying to find it.

7 Temmuz 2014 Pazartesi 15:58:52 UTC+3 tarihinde Gerald yazdı:

[Gerald Coley]

These transistors, they are active low. We can only sink and drive 6mA. You could try adding a pullups to each signal to pull the voltage higher, Tie then to 3.3V.

Gerald

[John Syn]

From: Gerald Coley <ger...@beagleboard.org>
Reply-To: "beagl...@googlegroups.com" <beagl...@googlegroups.com>
Date: Monday, July 7, 2014 at 1:19 PM
To: "beagl...@googlegroups.com" <beagl...@googlegroups.com>
Subject: Re: [beagleboard] Using Relay Module With BBB

These transistors, they are active low. We can only sink and drive 6mA. You could try adding a pullups to each signal to pull the voltage higher, Tie then to 3.3V.

I think your initial assessment was correct. If VCC is 5V or higher, there is no way to switch these transistors off. This relay board design isn’t suitable for the BBB. Best to replace the PNP transistors with NPN and swap the power pins. GND now becomes 5V/12V and the VCC now becomes 0V. Probably have to turn the LEDs around. 

Regards,

John

[colone...@gmail.com]

Thanks for the replies.
I decide to sell my relay board locally and make a new one by myself.
I have searched internet and find two options. I think they will both work with beaglebone black.
Please tell me: Will they work or not?

http://oi59.tinypic.com/2vcywrt.jpg
http://oi59.tinypic.com/ibhxkj.jpg

[John Syn]

From: <colone...@gmail.com>
Reply-To: "beagl...@googlegroups.com" <beagl...@googlegroups.com>
Date: Friday, July 11, 2014 at 1:16 PM

To: "beagl...@googlegroups.com" <beagl...@googlegroups.com>
Subject: Re: [beagleboard] Using Relay Module With BBB

Thanks for the replies.
I decide to sell my relay board locally and make a new one by myself.
I have searched internet and find two options. I think they will both work with beaglebone black.
Please tell me: Will they work or not?

http://oi59.tinypic.com/2vcywrt.jpg

The first one will work best. 

Regards,

John

http://oi59.tinypic.com/ibhxkj.jpg