Re: [beagleboard] Newbie how to turn a SPDT Relay(30A) on and off connected to a beaglebone green

2016-08-25 Thread 'Mark Lazarewicz' via BeagleBoard 
John your feedback is always uesefull how refreshing

  From: John Syne 
 To: beagleboard@googlegroups.com 
 Sent: Thursday, August 25, 2016 12:51 AM
 Subject: Re: [beagleboard] Newbie how to turn a SPDT Relay(30A) on and off 
connected to a beaglebone green
   



On Aug 24, 2016, at 7:24 PM, Przemek Klosowski  
wrote:


On Tue, Aug 23, 2016 at 5:18 AM,  wrote:


When I got my new bbgw I ran an internet search to find how to use the relay 
and did not find an easy answer, so here goes:
1. The Grove - SPDT Relay(30A) - uses +5V , so you need to solder the third pin 
of that groove connector. Disconnect it from the board, and connect it to the 
input 5v power.


It seems that your relay requires nominal 5V coil voltage and 185mA coil 
current. This is far beyond what a BBB pin can provide: they put out 3.3V and 
barely above 10mA. Additionally, switching the coil on and off generates 
inductive spikes that are likely to damage the BBB output circuits. You need 
some sort of coil driver; I suggest buying something, e.g one of 
http://blog.machinekit.io/p/hardware-capes.html, or building your own circuit 
like this one http://i.stack.imgur.com/OhY9d.png

This image is incomplete. You still need a diode across the relay coil or the 
transistor collector will see a much higher potential than the supply rail. 
Regards,John


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Re: [beagleboard] Newbie how to turn a SPDT Relay(30A) on and off connected to a beaglebone green

2016-08-24 Thread John Syne 


> On Aug 24, 2016, at 7:24 PM, Przemek Klosowski  
> wrote:
> 
> 
> 
> On Tue, Aug 23, 2016 at 5:18 AM, mailto:niv...@gmail.com>> 
> wrote:
> 
> When I got my new bbgw I ran an internet search to find how to use the relay 
> and did not find an easy answer, so here goes:
> 1. The Grove - SPDT Relay(30A) - uses +5V , so you need to solder the third 
> pin of that groove connector. Disconnect it from the board, and connect it to 
> the input 5v power.
> 
> It seems that your relay requires nominal 5V coil voltage and 185mA coil 
> current. This is far beyond what a BBB pin can provide: they put out 3.3V and 
> barely above 10mA. Additionally, switching the coil on and off generates 
> inductive spikes that are likely to damage the BBB output circuits. You need 
> some sort of coil driver; I suggest buying something, e.g one of 
> http://blog.machinekit.io/p/hardware-capes.html 
> , or building your own 
> circuit like this one http://i.stack.imgur.com/OhY9d.png 
> 
This image is incomplete. You still need a diode across the relay coil or the 
transistor collector will see a much higher potential than the supply rail. 

Regards,
John
> 
> -- 
> For more options, visit http://beagleboard.org/discuss 
> 
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> .
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>  
> .
> For more options, visit https://groups.google.com/d/optout 
> .

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Re: [beagleboard] Newbie how to turn a SPDT Relay(30A) on and off connected to a beaglebone green

2016-08-24 Thread Przemek Klosowski 
On Tue, Aug 23, 2016 at 5:18 AM,  wrote:

When I got my new bbgw I ran an internet search to find how to use the
> relay and did not find an easy answer, so here goes:
> 1. The Grove - SPDT Relay(30A) - uses +5V , so you need to solder the
> third pin of that groove connector. Disconnect it from the board, and
> connect it to the input 5v power.
>

It seems that your relay requires nominal 5V coil voltage and 185mA coil
current. This is far beyond what a BBB pin can provide: they put out 3.3V
and barely above 10mA. Additionally, switching the coil on and off
generates inductive spikes that are likely to damage the BBB output
circuits. You need some sort of coil driver; I suggest buying something,
e.g one of http://blog.machinekit.io/p/hardware-capes.html, or building
your own circuit like this one http://i.stack.imgur.com/OhY9d.png

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[beagleboard] Newbie how to turn a SPDT Relay(30A) on and off connected to a beaglebone green

2016-08-23 Thread nivwiz 
When I got my new bbgw I ran an internet search to find how to use the 
relay and did not find an easy answer, so here goes:
1. The Grove - SPDT Relay(30A) - uses +5V , so you need to solder the third 
pin of that groove connector. Disconnect it from the board, and connect it 
to the input 5v power.
The groove connector pinout are:

J4 
1- I2C2_SCL - P9_19 
2- I2C2_SDA - P9_20 
3- VDD 3.3 
4- GND 

J5 
1- UART2_RXD - P9_22 
2- UART2_TXD - P9_21 
3- VDD 3.3 
4- GND

The pinout of the relay is:
1- Signal
2- not connected
3- +5V
4- GND

If you connect the relay to J4 use this python code, to toggle it on and off

import Adafruit_BBIO.GPIO as GPIO
import time
GPIO.setup("P9_19", GPIO.OUT)
while True:
GPIO.output("P9_19", GPIO.HIGH)
time.sleep(0.5)
GPIO.output("P9_19", GPIO.LOW)
time.sleep(0.5)



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