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hi when the controller is used in the external bus interface mode,how is the data sent to the POL.can we just directly set POL=data. and read from the POL as data=POL. thanks
When the external interface is enabled in SYSCON, BUSCON & ADDRSEL registers, a simple write to a memory location in the external space will cause the data to be strobed out on P0L and optionally P0H. The explanation is in the 167 Users Manual under External Bus and specific timing for the CPU you are using is in the diagrams at the end of it's data book. If you want to boot from external memory you must set the EA/ pin low during reset and hold the P0 pins at specific levels to set up the external bus for the first boot instructions. This is covered in the Users Manual under External Bus and the Reset sections. Best luck Scott