Accessing external memory with the ST92F150 eval board

[johan239955_stm1_stmicro]

Posted on September 29, 2003 at 06:57

Accessing external memory with the ST92F150 eval board

[johan239955_stm1_stmicro]

Posted on May 17, 2011 at 11:33

Does anyone have any example code for accessing external memory with the ST92F150 ?

I have tried accessing the external RAM (U3) on the ST9GP-EVAL board using a ST92F150-EMU2 emulator but I keep running into problems

: STVD9 doesn't seem to be reading back the correct values.

Do you know if there are any issues with the external memory peripheral or the eval board ?

If you have any example code, could you please send it to me ?

Jojo

[albert23]

Posted on May 17, 2011 at 11:33

The access mode used on the Eval board is not correct in regards with the RAM specification : the /DS (connected to /G) should not be low during the write access. Therefore, a modification to the ST9GP-EVAL PCB MUST be done by the user:

''2/ With some NVRAM lots, the memory cannot be accessed with the external memory access mode used on the Motherboard (MC=0, refer to the product datasheet). This mode is not compatible with all memory types as the DS signal is pulled down by the microcontroller during a WRITE Operation. In this case, the U1 component (74HC04) must be removed, and pins 3 and 4 must be connected together. Then the memory can be accessed using MC=1 mode (refer to the product datasheet). In this mode the OEN signal is pulled down only during the READ operation.''

Also, I have attached four different example codes for accessing the external RAM using mapped and unmapped data.

[ritu]

Posted on May 17, 2011 at 11:33

I have tried to run all the 4 porgrams in the zip file both on silicon and emulator. But none of the program seems to give right results. i.e. write and read values don't match. And in case of emulator while writing it actually makes access to memory location 210000 - 210009

which is non- existant in our case. And during read perhaps somewhere in segmet 0.

Can you please help !!!

Ritu