add slides

[libreriscv.git] / pinmux / pinmux_chennai_2018.tex

diff --git a/pinmux/pinmux_chennai_2018.tex b/pinmux/pinmux_chennai_2018.tex
index d8fd4b437a7e1afd66c1025669a95d4e77fd902d..9ca9d640097afe76668327b8faddc0ef1f282e20 100644 (file)
--- a/pinmux/pinmux_chennai_2018.tex
+++ b/pinmux/pinmux_chennai_2018.tex
@@ -66,7 +66,7 @@
          Summary: it's all about making more money!\vspace{4pt}
    \item How? By multiplexing many more functions (100 to 1,200) than there
          are actual available pins (48 to 500), the required chip package
-            is far less costly and the chip more desirable\vspace{4pt}
+            is cheaper, smaller, and more versatile\vspace{4pt}
    \item What? A many-to-many dynamically-configureable router of
          I/O functions to I/O pins
   \end{itemize}
@@ -260,7 +260,7 @@
 
  In/out: {\bf Note: these all require multiplexing }
  \begin{itemize}
-   \item Output-Enable (aka Input disable): switches pad to In or Out
+   \item Output-Enable (aka Input disable): switches pad to Out or In
    \item Output (actually an input wire controlling pin's level, HI/LO)
    \item Input (actually an output wire set based on pin's driven level)
  \end{itemize}
@@ -288,7 +288,7 @@
 
  \begin{itemize}
    \item Standard Mux design {\bf cannot deal with many-to-one inputs}\\
-            (SiFive IOF source code from Freedom U310 cannot, either)
+            (SiFive IOF source code from Freedom E310 cannot, either)
             \vspace{4pt}
    \item I/O pad configuration conflated with In-Muxer conflated with
                 Out-Muxer conflated with GPIO conflated with EINT.
@@ -318,16 +318,22 @@
 
 \frame{\frametitle{GPIO (only): Simplified I/O pad Diagram (FN only)}
  \begin{center}
-  \includegraphics[height=2.5in]{reg_gpio_pinblock.jpg}\\
-  {\bf 3 wires: IN, OUT, OUTEN (also = !INEN) }
+  \includegraphics[height=1.3in]{reg_gpio_pinblock.jpg}
  \end{center}
+ \begin{itemize}
+   \item GPIO In/Out/Direction is just another FN (effectively)
+   \item 3 wires: IN, OUT, OUTEN (=INEN\#)
+   \item FN however may be output-only (UART\_TX), input-only (UART\_RX)
+         or bi-directional (I2C\_SDA) and Bus-controlled.
+   \item GPIO is definitely bi-directional and under Register control
+ \end{itemize}
 }
 
 
 \frame{\frametitle{Output Muxer (very simple)}
  \begin{center}
   \includegraphics[height=1.1in]{reg_gpio_out_mux.jpg}\\
-  {\bf Ouput Muxer using 2-bit address selection}\\
+  {\bf Output Muxer using 2-bit address selection}\\
  \end{center}
  \begin{itemize}
    \item Very straightforward (deceptively so, like SRAM cells)