Avinash Mohan

MC9S12NE64 External Bus Access

Discussion created by Avinash Mohan on Jun 18, 2009
Latest reply on Jun 23, 2009 by Avinash Mohan




We are using the MC9S12NE64 external bus to access some external memory device. We are using connections similar to that of the EVB9S12NE64 evaluation board on the hardware side. Only the XCS signal is used as the chip-select signal for the peripheral. When we were trying out a code to access the external bus, we observed that we are not getting the XCS (external chip-select) signal  to assert for the bus-cycles. We are using the following configuration to initialize the external bus interface:

MODE register is set for Normal Expanded Wide Mode access (MODC=MODB=MODA=1,IVIS=EMK=EME=0)

The Read/Write pin function was enabled by setting the RDWE bit (bit 2) of the PEAR register.


Is there some configuration steps which I  have missed out? Or, am I doing it in the wrong way?


Pls help...



Thanks and regards,