Hello,
I'm using an LPC1788 with a MT48LC16M16 SDRAM chip. All works well and I do not have any issues with the external memory in normal operation.
I use a bootloader to configure the external memory and run a memory check. My problem is when I get a watchdog reset in the main application (I'm causing them on purpose for testing) the configuration of the external SDRAM runs in the bootloader and one of two things happens:
1) Everything works exactly the same as on a power up (50% of the time)
2) As soon as I try and access the memory I get a fault that kills my debugger. (The other 50% of the time)
Does anyone have any idea what is going on? Note I have tried this with SCB bit 1 on/off no difference. I've also tried not re-configuring the EMC when it's a watchdog reset but this seems to fail every time.
Does anyone know how to safely and surely reset this SDRAM?
Thanks
M
Hi,
For me, if you lose sync for refresh with your SDRAM you lose everything. So if you reboot your micro, you lose your sync and you have to reset your ram.
In my application, I preferred the SRAM and backup my data with a capa.
good luck...
but this seems to fail every time
The configuration itself or startup?
Thanks for the replies.
@JB JB losing all the SDRAM data is not a problem (This is expected when a watchdog reset occurs for my design).
@Tamir - By fail every time I mean the SDRAM configuration/initialization. In other words the bootloader runs fine, it configures the SDRAM but at the first point of access of the external ram it hard faults.
I also have some external NOR and because this device has a reset line I never get any issues. With the SDRAM it's like I'm not forcing it to reset properly.