Input Registers for 32-bit Ports A

Maria Ivanovna

Hello Forum ,
in the manual of the propeller , they wrote :

Input Registers for 32-bit Ports A, INA:

a low (0) bit indicates the corresponding I/O pin senses ground, and a

high (1) bit indicates the corresponding I/O pin senses VDD (3.3 volts).

I have a 3.4volts, this value can distroy the propeller demo board ?or it's better i will change my schema to have exactly 3.3volts? and to don't risk with it
Thank you in advance and have a nice day ,
Masha

Leon

Use a series resistor to drop the voltage.

Leon

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Amateur radio callsign: G1HSM

MagIO2

According to the Datasheet a supply voltage of 2.7V - 3.6V is in the range. If used as input I'd expect no problem with 3.3V supply and 3.4V input-level.

But during hardware and software development/testing it's always a good idea to have a series resistor, as it protects your propeller in case you accidently set the dira to output on a pin that's connected to a device already driving the line.

Peter Jakacki

Just as a side note, the logic high input is anything above 0.6Vdd which is approximately 2V whereas a logic low input is anything less than 0.3Vdd or 1V.

Also inputs can swing higher than Vdd by up to 0.3V so 3.4V is safe and doesn't "need" current limit resistors although it is a good idea to include them as has been mentioned.

Recommended operating voltage for the Propeller is 3.3V with a safe use to 3.6V. The Prop may survive voltages higher than these but there are no guarantees for how long etc. I have used 3.6V before for interfacing outputs to standard 5V logic.

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*Peter*

Maria Ivanovna

Thanks for your reply , i will try it and give you the results

MagIO2

Who exactly gets the fried propeller??? [noparse]:o[/noparse])