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authorWerner Almesberger <werner@almesberger.net>2016-07-01 10:26:40 -0300
committerWerner Almesberger <werner@almesberger.net>2016-07-01 10:26:40 -0300
commitbbab61156feb33fb0215841c9b8ef87dd20f694c (patch)
tree41e386ac8e28852a7e6666e90880a3ea76675669 /ir
parent1bc246012b0369cbe5d63d757ff100ced602f36e (diff)
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ir/ir.tex: reorganize sections (optoelectronics section; move conflict/undriven)
Diffstat (limited to 'ir')
-rw-r--r--ir/ir.tex107
1 files changed, 57 insertions, 50 deletions
diff --git a/ir/ir.tex b/ir/ir.tex
index b580806..5482743 100644
--- a/ir/ir.tex
+++ b/ir/ir.tex
@@ -493,7 +493,61 @@ with {\eitact}. An unused signal is marked with {\unspec}.
% -----------------------------------------------------------------------------
-\section{Possible component selection}
+\section{Conflict resolution}
+\label{conflict}
+
+%
+% Conflict resolution rules:
+%
+% Jul 15 21:49:18 <DocScrutinizer05> wpwrak: both, and collision is a
+% non-defined case, but we will make sure that the UART TX has a series R
+% so it can get overridden by HB, given HB driver has lower ESR. Same for
+% RX from photodiode which HB can override before it raches UART
+
+When a line is driven as output from multiple sources, the following
+conflict resolution strategy shall be applied:
+
+\begin{tab}
+\begin{tabular}{l|ll|l}
+Line & Dominant & Subordinate & Applicable IR system states \\
+\hline
+TX & Hackerbus & CPU & IrDA, IR-UART \\
+CTS & Hackerbus & CPU & CIR \\
+RX & Hackerbus or CPU & IR sensor & CIR, IrDA, IR-UART \\
+\end{tabular}
+\end{tab}%
+%
+Conflicts between CPU and Hackerbus on RTS or RX result in undefined
+behaviour and should be avoided. Conflict increases overall power
+consumption and should be avoided during normal system operation.
+
+Precedence is established by series resistors next to the CPU for TX and
+CTS, and a series resistor on the digital output of the IR receiver,
+before entering the RX line.
+
+% -----------------------------------------------------------------------------
+
+\section{Undriven signals}
+\label{undriven}
+
+The IR circuit must be tolerant to a UART signal being driven by neither
+CPU, Hackerbus, or the IR receiver. Whether this tolerance is achieved by
+pulling the signal to a safe state or by applying a more general
+protection against incorrect inputs is left as an implementation choice.
+
+Control signals that float after CPU reset and that are not ignored by the
+IR subsystem must be pulled to a safe state.
+
+% -----------------------------------------------------------------------------
+
+\section{Optoelectronics}
+
+The following sections discuss the selection of the optoelectronic devices,
+and their physical placement.
+
+% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+\subsection{Possible component selection}
% Agreement on VSMB2948SL LED
%
@@ -558,9 +612,9 @@ available SMT parts all had rise and fall times in the order of 15 $\mu$s,
which would limit the maximum signal frequency to only about 30 kHz.
They do not allow improving response time by biasing the transistor.
-% -----------------------------------------------------------------------------
+% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-\section{Component placement}
+\subsection{Component placement}
\label{placement}
The N900 case has a window with an integrated IR filter of unknown
@@ -595,53 +649,6 @@ least 5 mm between components and between components and walls.
% -----------------------------------------------------------------------------
-\section{Conflict resolution}
-\label{conflict}
-
-%
-% Conflict resolution rules:
-%
-% Jul 15 21:49:18 <DocScrutinizer05> wpwrak: both, and collision is a
-% non-defined case, but we will make sure that the UART TX has a series R
-% so it can get overridden by HB, given HB driver has lower ESR. Same for
-% RX from photodiode which HB can override before it raches UART
-
-When a line is driven as output from multiple sources, the following
-conflict resolution strategy shall be applied:
-
-\begin{tab}
-\begin{tabular}{l|ll|l}
-Line & Dominant & Subordinate & Applicable IR system states \\
-\hline
-TX & Hackerbus & CPU & IrDA, IR-UART \\
-CTS & Hackerbus & CPU & CIR \\
-RX & Hackerbus or CPU & IR sensor & CIR, IrDA, IR-UART \\
-\end{tabular}
-\end{tab}%
-%
-Conflicts between CPU and Hackerbus on RTS or RX result in undefined
-behaviour and should be avoided. Conflict increases overall power
-consumption and should be avoided during normal system operation.
-
-Precedence is established by series resistors next to the CPU for TX and
-CTS, and a series resistor on the digital output of the IR receiver,
-before entering the RX line.
-
-% -----------------------------------------------------------------------------
-
-\section{Undriven signals}
-\label{undriven}
-
-The IR circuit must be tolerant to a UART signal being driven by neither
-CPU, Hackerbus, or the IR receiver. Whether this tolerance is achieved by
-pulling the signal to a safe state or by applying a more general
-protection against incorrect inputs is left as an implementation choice.
-
-Control signals that float after CPU reset and that are not ignored by the
-IR subsystem must be pulled to a safe state.
-
-% -----------------------------------------------------------------------------
-
\section{Transmitter circuit}
The transmitter circuit consists of the configuration