how are you driving the relays ? i hope you are using a relay driver IC
On 2/24/2015 10:30 AM, [email protected] wrote: > I have noticed that if more than one pin is set to output-HIGH, the > most recent pin output request provides 3.3v out while the others are > sacraficed (1.5v, .5v, etc). I am using the Adafruit_BBIO.GPIO library > to control the pins. I am building a "climate control" system, and > using the BBB and a DHT22 temperature/humidity sensor to operate > relays to supply 120vAC to components (lights, heater, water pump). > > I have: a door switch SPDT(P9_11) for safety override, a DPDT(P8_10 > and P8_12) for automatic and manual operation, and a 3-24vDC/0-240vAC > relay for suppling power to a lamp. > > The P8_12 and P9_11 always have power. If the door switch is > activated(P9_11) it activates the relay and bypasses the DPDT switch. > If the DPDT switch is set to "manual"(P8_12) the relay is activated. > Otherwise if the temperature from the DHT22 is above or below a set > limit, and the DPDT switch is in "automatic"(P8_10), the relay is > activated accordingly. > > Pseudo code: > import libraries > > # Set pins P8_12 and P9_11 to output 3.3v > GPIO.output(P8_12,HIGH) > GPIO.output(P9_11,HIGH) > > while 1: > read temperature > > # Decide to turn P8_10 on/off based on temperature > if temp<28: > GPIO.output(P8_10,HIGH) > else: > GPIO.output(P8_10,LOW) > # Loop indefinately > > Here is the problem: > If I run a test program with only the door switch the light turn > on/off as expected. If I execute the above code the DPDT switch and > auto/manual control works as expected however the door switch will not > supply enough power to activate the relay. When the above code is > running and P8_10 turn on, or if the DPDT switch is set to > manual(P8_12) the voltage across the door switch(P9_11) drops to ~1.5v > and is less than the required 3v to activate the relay. > > Question: > Can the BBB supply 3.3v out for more than one pin simultaneously, or > will i need to add an amplifier circuit to each output? > > I can attach full code and schematic if it would be helpful. In the > end there will be 8 relays, of which up to 5 will be activated > simultaneously. > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google > Groups "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send > an email to [email protected] > <mailto:[email protected]>. > For more options, visit https://groups.google.com/d/optout. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
