# Rising edge duration of a low to high pulse

In a device I am using, I see the following in the description...

"At start-up, the module requires an ON_OFF pulse sent from the host. A second pulse sent from the host will re-enter hibernate mode. The ON_OFF pulse needs to be the rising edge of a low to high pulse, this needs to be longer than 90us."

I am not clear on what the requirement is. For time being, I have the ON_OFF line being tied to the application of power. When I switch on, this line will transition from a low to a high... and stay high...probably very quickly.

I do not believe what I am doing is correct. I am trying to understand the interpretation of what is asked and I think it is really the following..

Does the above mean..(High voltage is 1.8V). "When you apply power and switch on, make the transition from 0 volts to 1.8 volts take at least 90us?"

This is of course without regard for if the line ever goes low again.

If that is so, could I accomplish the above with an RC circuit on the power line?

What I quoted is contained in that link. There are other aspects of this chip which I don't quite fully understand from he datasheet. Yet, the fact that it is not running properly is probably related to the On pulse and what I initially setup.

• What device? Where in the spec? Nov 21, 2018 at 23:23
• A link to the datasheet would be helpful, but very likely they mean the pulse width should be at least 90 us, not the rising edge. Nov 22, 2018 at 2:01
• I added a link, I am also not clear on the use of WAKUP and external memory. The main question related to what the 90us requirement is actually on. Nov 22, 2018 at 4:40
• From a practical perspective, it is totally unreasonable to expect a rising edge to be 90us. Most likely they are saying that the high time of the pulse must be 90us or more. (This is probably because they only sample it ever 80us or so, so in order to make sure they don't miss it, they tell you that your pulse needs to be high for 90us). Nov 22, 2018 at 4:45
• That's a long, long data sheet. How about you help us a little more by saving our time, and telling us what page number the offending text is at. I've not yet found it browsing from pages 1 to 16, so I've quit trying to answer this question. I'll go somewhere where the OP is actually helping me to help himself. Nov 22, 2018 at 4:59

For the ON_OFF pin, the pulse width must be at least 90us, not the rising edge.

If not used by the host controller, ON_OFF needs to be connected to the WAKUP pin. The WAKUP pin then controls the ON_OFF Pin in a way that the module is automatically set to a full power state.