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Timestamp:
Sep 3, 2010, 2:56:55 PM (9 years ago)
Author:
mulligan
Message:

Up to describing 8051 SFRs in presentation

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1 edited

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  • Deliverables/D4.1/Presentation/Paris-September-2010.tex

    r33 r34  
    5757\frametitle{Bit memory}
    5858\begin{itemize}
    59 The 8051 provides 128 bit variables to the user, at locations
     59\item
     60The 8051 provides 128 bit variables to the user, numbered 00h--7Fh.
     61\item
     62Like the `R' registers, bit memory is really a part of internal RAM.
     63\item
     64Bit memory is located at internal RAM addresses 20h--2Fh, therefore writing FFh to internal RAM address 20h effectively sets bits 00h through 07h.
     65\item
     66Though part of internal RAM, the 8051 provides specific instructions for setting and clearing bits in bit memory.
    6067\end{itemize}
    6168\end{frame}
     69
     70\begin{frame}
     71\frametitle{A note on the stack pointer (SP)}
     72\begin{itemize}
     73\item
     74At powerup, the 8051 initialises the SP to address 07h.
     75\item
     76The stack therefore starts at 08h and expands upwards.
     77\item
     78Care must be taken if we decide to use the alternative register banks to initialise the stack pointer above the chosen bank.
     79\item
     80Further, if using bit variables, it's a good idea to initialise the stack point above address 2Fh, to ensure bit variables are not overwritten by the growing stack.
     81\end{itemize}
     82\end{frame}
     83
     84\begin{frame}
     85\frametitle{Special function registers (SFRs)}
     86\end{frame}
     87
    6288\end{document}
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