Putting into sleep mode and waking up RS 485 transceiver

[Inkwaterman]

RS 485 wake up problem

Hi !

I have the following question:

I have to do a network of devices based on PICmicro.
This network in a RS485 and the device is battery powered.

For save the battery I put in sleep mode the PIC micro and I want that when there's a RS485 comunication all pic wake up for process the incoming packets and return in sleep mode.

I read the feature of many RS485 tranceiver and I saw that they use a current of quite 1 mA.

I saw also that is possible put in sleep mode some kind of tranceiver.

Is possible to put the tranceiver in sleep mode and wake it up , with the PIC , when the RS485 line become busy ?

Which kind of IC I have to use ?


Thanks .

 

[Davood Amerion]

RS 485 wake up problem

I think you can use one stage transistor to detect AB line (in RS485) voltage transition.
connect collector of transistor to one of uc input pin.
and activate (program) as, interrupt on pin change.