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My project involves using Serial I/O port. The code written was working fine when there was EXTERNAL XRAM on board. We have been using Winbond 78E516 cpu. Now the EXTERNAL XRAM was removed from the design. I have tried to utilize the INTERNAL XRAM in replace of EXTERNAL RAM, and the code does not working at all. Using the scope to monitor the TX or RX pin of the CPU, I did not see anything. I have tried all the options: USE ON_CHIP XRAM checked, USE ON-CHIP ROM checked .... but no luck !! I even added the STARUP file to the project by including: setting sfr CHPCON bit4 .. still no luck. Does anybody in the forum experience such problem.
Hi Jimmy, I've solved that problem before. According to the data sheet of Winbond 78E516, you can set it up to use the on-chip XRAM as PDATA or simply use it as XDATA. My suggestion is adding the following code in the startup.a51 before you clear the on-chip XRAM:
MOV CHPENR,#87H MOV CHPENR,#59H ORL CHPCON,#00010000B ; enable AUX-RAM MOV CHPENR,#00H