Ensuring Propeller powers up

william chan

Sometimes when I plug the power supply to the board, the Propeller chip fails to start up.

I have to pull out the plug, wait a few seconds and then plug in the power again.

How to ensure the Propeller chip starts up every time correctly?

Duane Degn

A little more detail would help. What kind of board are you using? What kind of power supply?

I've had a couple problems with a Propeller board not powering up consistently but it has always been my fault do to loose wires or not enough capacitors on the Vdd pins. These have always been homemade boards or breadboarded circuits.

Duane

Cluso99

This is a typical problem caused by the power supply "bouncing" on and off as you plug it in. Try plugging it in and then turning on the power at the wall and you should find it works every time, or otherwise you have a problem.

william chan

I use a switching 12v 3a power supply "brick."

I have a 470uF electrolytic cap on the 12v line, 10uF smd ceramic on the 5v line and one 10uF smd ceramic near the 78L33 3V regulator and another 10uF smd ceramic near the Prop D40.

Should I reduce the 470uF capacitance or change it to tantalum type to reduce the bouncing?

Powering up from the wall seems to work most of the time.

Cluso99

The bouncing will happen - nothing really you can do about it. This is because when the contact is made it may only be for a short time before a break and this time may not be enough to charge a cap to avoid the bounce. While switches in fact have bounce, they are short enough to not usually cause this problem whereas this is human controlled bounce over a longer time.

The only alternative is to fit a switch into the power supply line and leave the board plugged in.