Phil Green

Problem with HCS08AW60 in 3.3v system

Discussion created by Phil Green on Oct 31, 2006
Latest reply on Nov 6, 2006 by Jim Pantera
I am operating an AW60 in a 3.3v system.
By default on power-on reset the LVD system in enabled to reset the uP when the voltage drops below the lower LVD threshold (2.56v). On two occasions I have found that the system is being held in reset because the threshold has been changed to the upper level(4.4v) relevant for a 5v system. I have proved this by increasing the supply voltage to around 5v and the system starts, lower it back to 3.3 and the uP is held in reset without performing a POR.

I have not actively changed the LVWV bit in SPMSC2 to a "1". The bit changing to a "1" in a 3.3v system is fatal!

My I don't think my code is crashing and it is highly unlikely to be setting this bit, or is there a problem with the part itself.

I would prefer that the threshold selection bit was set in flash at programming time!

I look forward to your comments.

Phil Green