If you probe an area of SDRAM memory space that does not have memory populated, you may experience lock up issues occasionally. It has been found by Freescale that the SDRAMC does not handle the transfer error acknowledge (/TEA) signal from the XLB Arbiter properly. When the XLB Arbiter times out during a SDRAMC cycle and issues the /TEA, the SDRAMC can behave unpredictably.

This issue was found to exist LogicLoader since LogicLoader will automatically detect the SDRAM size by probing the memory space. This probe algorithm will write and read back data at various locations on the SDRAM bus to identify the presence of RAM. Typically writing and reading to a memory space that does not have any SDRAM present should simply yield invalid data. However, on the ColdFire platform, the bus arbiter for the SDRAM controller may lockup when accessing memory space that is not populated with memory.

Logic has resolved this issue in LogicLoader for all MCF547x/8x Fire Engines. If you are experiencing this in LogicLoader please update to the latest version of LogicLoader on the product downloads page for your particular Fire Engine.