Matrix user forums

Hi!

Today i noticed that the EB006v9 booted up my system when USB was not connected and the PSU was taken online... I have the power jumper on USB side?
Then i tested this on EB006v8 and it doesnt boot up automatically (does not get power) when i have jumper on USB side and i put PSU on?

Is there some kind of error inside the schematics or have you put that eb006v9 to some kind of autodetect mode?

Thanks for the finding, yes you are right the boards I have here also do the same thing.

I believe the problem has come from a old problem where we used to only power the USB host chip when the USB cable was present. This is how the v6 EB006 board worked.

We then added more connections from the target chip to the host chip to allow ICD to function and this inserted a curious problem. When the USB host chip is not powered the target chip can actually power the ghost chip via the I/O pins which can lead to some strange problems. So the fix was for us to always power the host chip when the target chip is powered. If you look at the datasheet the input voltage to a pin should never be more than VCC + 0.6V so if VCC is at 0V and the I/O is at 5V then there is a problem.

With Ghost comes even more connections so we had to take extra steps to ensure the host (ghost) chip is always suitably powered. This is therefore why the Power LED is lighting when it probably shouldn't be. It shouldn't cause any problems but your right in it is a bit misleading.