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Digital I/O
the digital output drop to 0
Hi,
i have this circuit to control the direction of brushless dc motor
to remove the brake the brake should connected to Black and this happen after i give D0 and D3 high and this one work fine
to move back same we have to connect brake + back + black then D0+D1+D3+D4should high and this one work fine
when i want to move Forward should BRAKE+BACK +FRW+BLACK then the 6 pins should be high , but in this situation all the pins is low
any suggestion ?
the module i have 9403 and cdaq 9188
How much current do you need for those optocouplers? If any more than 10mA, then this actually makes sense.
The 9403 has an overcurrent protection in it. When you reach a certain total output current (spec claims 64mA), then the OCP kicks in an turns all of the outputs to high impedance. I would recommend finding some digital buffers that can supply more current for you optocouplers. I frequency use the 74ACT245SC.
@Eng.Tareq wrote:
so 64ma is per channal ?
No, 64mA total. Yeah, you definately need to find a buffer that can handle some current. That optocoupler could need 50mA for the control.
@Eng.Tareq wrote:
But how can i run until 4 PHOTOCOUPLER ? if i put 5 or 6 it go to over current state ?
That 50mA is a maximum. From the data sheet, it looked like 20mA was a typical. It didn't have a spec for minimum current. But running 4 might just be doable (assuming no more than 16mA per optocoupler) and then a fifth causes the OCP in the DIO module.
Again, put in a digital buffer that can handle the current to control those optocouplers.
