X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=pinmux%2Fpinmux_chennai_2018.tex;h=37826be6ac81530371e0b5b04fadc6831c598511;hb=101740190d4512e6fc9c17a78757113c18712f4e;hp=a1bcb5a9173ea41ed9a503a1572d9f98af938bd5;hpb=48ccfa4d3bfb517dc72d7e828ec8bcc5631a2c5f;p=libreriscv.git

diff --git a/pinmux/pinmux_chennai_2018.tex b/pinmux/pinmux_chennai_2018.tex
index a1bcb5a91..37826be6a 100644
--- a/pinmux/pinmux_chennai_2018.tex
+++ b/pinmux/pinmux_chennai_2018.tex
@@ -14,7 +14,8 @@
    \begin{center}
     \huge{Pin Multiplexer}\\
     \vspace{32pt}
-    \Large{(Auto-generating documentation and resources for a Pinmux)}\\
+    \Large{Auto-generating documentation, code \\
+			and resources for a Pinmux}\\
     \vspace{24pt}
     \Large{[proposed for] Chennai 9th RISC-V Workshop}\\
     \vspace{16pt}
@@ -31,6 +32,102 @@
 }
 
 
+\frame{\frametitle{Glossary}
+
+ \begin{itemize}
+   \item Pin: an I/O pad.  May be driven (input) or may drive (output).
+   \item FN: term for a single-wire "function", such as UART\_TX,
+	     I2C\_SDA, SDMMC\_D0 etc.  may be an input, output or both
+		 (bi-directional case: two wires are always allocated, one
+		  for input to the function and one for output from the function).
+   \item Input Priority Muxer: a multiplexer that has N selector
+		 wires and N inputs, where the lowest (or highest) indexed
+		 "selector" that is enabled results in its corresponding
+		 input being routed to the output.
+   \item Output Demuxer: a one-to-many "redirector" where a single
+	     input is "routed" to any one of a number of outputs, based
+	     on a selection address.
+   \item GPIO: general-purpose reconfigureable I/O (Input/Output).
+  \end{itemize}
+}
+
+
+\frame{\frametitle{Muxer cases to handle}
+
+ \begin{itemize}
+   \item Many FN outputs to Many Pins: no problem\\
+	     (weird configuration by end-user, but no damage to ASIC)\vspace{10pt}
+   \item One Pin to Many FN inputs: no problem\\
+         (weird configuration by end-user, but no damage to ASIC)\vspace{10pt}
+   \item Many Pins to One FN input: {\bf Priority Mux needed}\\
+	     No priority mux: Pin1 = HI, Pin0 = LO, ASIC is damaged\vspace{10pt}
+   \item Some FNs (I2C\_SDA, SD\_D0..3) are I/O Buses\\
+	     Bi-directional control of the Pin must be handed to the
+	     FN\vspace{10pt}
+   \item TODO\vspace{10pt}
+  \end{itemize}
+}
+
+
+\frame{\frametitle{Standard GPIO 4-way in/out Mux and I/O pad}
+ \begin{center}
+  \includegraphics[height=2.5in]{../shakti/m_class/mygpiomux.jpg}\\
+  {\bf 4-in, 4-out, pullup/down, hysteresis, edge-detection (EINT)}
+ \end{center}
+}
+
+
+\frame{\frametitle{Register-to-pad "control" settings}
+ \begin{center}
+  \includegraphics[height=2.5in]{reg_gpio_cap_ctrl.jpg}\\
+  {\bf pullup/down, hysteresis, current, edge-detection}
+ \end{center}
+}
+
+
+\frame{\frametitle{In/Out muxing, direction control}
+ \begin{center}
+  \includegraphics[height=2.5in]{reg_gpio_fn_ctrl.jpg}\\
+  {\bf Note: function can control I/O direction}
+ \end{center}
+}
+
+
+\frame{\frametitle{Simplified I/O pad Block Diagram}
+ \begin{center}
+  \includegraphics[height=2.5in]{reg_gpio_pinblock.jpg}\\
+  {\bf 3 wires: IN, OUT, OUTEN (also = !INEN) }
+ \end{center}
+}
+
+
+\frame{\frametitle{Output (and OUTEN) Wiring. 2 pins, 2 GPIO, 2 Fns}
+ \begin{center}
+  \includegraphics[height=2.5in]{reg_gpio_out_wiring.jpg}\\
+  {\bf Reg0 for Pin0, Reg1 for Pin1, Output and OUTEN same mux }
+ \end{center}
+}
+
+
+\frame{\frametitle{Input Selection and Priority Muxing}
+ \begin{center}
+  \includegraphics[height=0.75in]{reg_gpio_comparator.jpg}\\
+  {\bf Muxer enables input selection}\\
+  \vspace{10pt}
+  \includegraphics[height=1.25in]{reg_gpio_in_prioritymux.jpg}\\
+  {\bf However multiple inputs must be prioritised }
+ \end{center}
+}
+
+
+\frame{\frametitle{Input Mux Wiring}
+ \begin{center}
+  \includegraphics[height=2.5in]{reg_gpio_in_wiring.jpg}\\
+  {\bf Pin Mux selection vals NOT same as FN selection vals}
+ \end{center}
+}
+
+
 \frame{\frametitle{Summary}
 
  \begin{itemize}