FLiP Module Reset Question

CJMJ

I'm powering mine from the 5-9v pin. I know if you plug in the USB cable it decides which source to draw power from, however, plugging in the USB cable causes it to reset itself. Is that normal?

Francis Bauer

This behavior is normal and is due to the DTR control line from the FTDI USB interface chip going to the RESn (Reset) of the Propeller MCU, usually through a transistor circuit.

There are some methods people have done on other Parallax boards to "disable" this behavior when using an external power source.
Here is one solution/suggestion related to the Propeller BOE board:

Question: PropBOE on ext power stops/resets when pulling/inserting USB cable

Answer:

This is a known behavior that's common to most USB microcontroller interfaces.
When you "pull/insert the plug" on the USB connection, there's a short reset pulse
produced as the DTR control line floats. There's no easy fix on the PropBOE.

If you were designing your own board, you'd simply put a jumper or switch
between the Prop's reset line and the collector of the reset transistor in the
DTR interface. Switch or jumper open ... no reset when you remove the USB cable
or close the USB serial port. You do need this connection for programming.

You may be able to do something like this for your FLiP module, but it would require you to modify/remove/add some parts on the FLiP module. Perhaps someone has a simple modification/solution...

kwinn

CJMJ wrote: »

I'm powering mine from the 5-9v pin. I know if you plug in the USB cable it decides which source to draw power from, however, plugging in the USB cable causes it to reset itself. Is that normal?

That is normal behavior. Based on the schematic the simplest solution may be to place jumper pins on either side of R201. When the pins are shorted the reset transistor base is connected to ground and prevents the reset.

CJMJ

Thanks for the reply. That's what I needed to know.