Changeset 34

Timestamp:

Sep 3, 2010, 2:56:55 PM (10 years ago)

Author:

mulligan

Message:

Up to describing 8051 SFRs in presentation

File:

• Deliverables/D4.1/Presentation/Paris-September-2010.tex (modified) (1 diff)

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

@@ -57 +57 @@
 \frametitle{Bit memory}
 \begin{itemize}
-The 8051 provides 128 bit variables to the user, at locations 
+\item
+The 8051 provides 128 bit variables to the user, numbered 00h--7Fh.
+\item
+Like the `R' registers, bit memory is really a part of internal RAM.
+\item
+Bit memory is located at internal RAM addresses 20h--2Fh, therefore writing FFh to internal RAM address 20h effectively sets bits 00h through 07h.
+\item
+Though part of internal RAM, the 8051 provides specific instructions for setting and clearing bits in bit memory.
 \end{itemize}
 \end{frame}
+
+\begin{frame}
+\frametitle{A note on the stack pointer (SP)}
+\begin{itemize}
+\item
+At powerup, the 8051 initialises the SP to address 07h.
+\item
+The stack therefore starts at 08h and expands upwards.
+\item
+Care must be taken if we decide to use the alternative register banks to initialise the stack pointer above the chosen bank.
+\item
+Further, 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.
+\end{itemize}
+\end{frame}
+
+\begin{frame}
+\frametitle{Special function registers (SFRs)}
+\end{frame}
+
 \end{document}