| Line 66... |
Line 66... |
You should have received a copy of the GNU General Public License along
|
You should have received a copy of the GNU General Public License along
|
with this program. If not, see \hbox{<http://www.gnu.org/licenses/>} for a
|
with this program. If not, see \hbox{<http://www.gnu.org/licenses/>} for a
|
copy.
|
copy.
|
\end{license}
|
\end{license}
|
\begin{revisionhistory}
|
\begin{revisionhistory}
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|
0.3 & 11/07/2015 & Gisselquist & RTC--Light, and RTC--GPS added\\\hline
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0.2 & 7/11/2015 & Gisselquist & Date interface added\\\hline
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0.2 & 7/11/2015 & Gisselquist & Date interface added\\\hline
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0.1 & 5/25/2015 & Gisselquist & First Draft \\\hline
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0.1 & 5/25/2015 & Gisselquist & First Draft \\\hline
|
\end{revisionhistory}
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\end{revisionhistory}
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% Revision History
|
% Revision History
|
% Table of Contents, named Contents
|
% Table of Contents, named Contents
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| Line 103... |
Line 104... |
changes should run on any fundamental clock rate from about 66~kHz on up to
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changes should run on any fundamental clock rate from about 66~kHz on up to
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250~TeraHertz with varying levels of accuracy along the way.
|
250~TeraHertz with varying levels of accuracy along the way.
|
|
|
Distributed with this clock is a similar Real--Time Date module. This
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Distributed with this clock is a similar Real--Time Date module. This
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second module can track the day, month, and year while properly accounting
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second module can track the day, month, and year while properly accounting
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for varying days in each month and leap years, when they happen.
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for varying days in each month and leap years, when they happen. Also
|
|
distributed with the clock are a light version of the clock, offering no
|
|
LED nor seven segment display capability, and a GPS version, with an
|
|
interface allowing it to be synchronized to a GPS module.
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|
|
Together, the clock and date module offer a fairly full feature set of
|
Together, the clock and date module offer a fairly full feature set of
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capability: date, time, alarms, a countdown timer and a stopwatch, all
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capability: date, time, alarms, a countdown timer and a stopwatch, all
|
features which are available from the wishbone bus.
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features which are available from the wishbone bus.
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| Line 235... |
Line 239... |
Further, as with the clock time, setting any particular field of the date to
|
Further, as with the clock time, setting any particular field of the date to
|
all ones, such as setting the month to {\tt 8'hff}, will cause that portion of
|
all ones, such as setting the month to {\tt 8'hff}, will cause that portion of
|
the date to retain it's current value. In this way, one part of the date
|
the date to retain it's current value. In this way, one part of the date
|
may be set and not others.
|
may be set and not others.
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|
|
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\section{RTC--Light}
|
|
The RTC Light module is nearly identical to the RTC clock module, save that
|
|
it has been simplified for environments that have neither LED outputs nor
|
|
seven segment display to drive. Further, the time hack registers have been
|
|
replaced with read--only zero producing registers. Further, if the high
|
|
order bit of the wishbone address is fixed to zero, the clock speed will no
|
|
longer be adjustable--reducing the logic even further.
|
|
|
|
This module is independent of the RTC clock module.
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|
|
|
\section{RTC GPS}
|
|
As part of a GPS driven RTC solution, the RTC GPS module is provided. This
|
|
module will use an externally provided PPS signal, one clock pulse wide and
|
|
synchronized with the system clock, as well as an externally provided
|
|
clock speed register. It has no time hack capability. Further, when the
|
|
external GPS valid line is true, these additional two inputs will drive the
|
|
clock.
|
|
|
|
Operating this clock requires a variety of external GPS circuitry: a clocked
|
|
PPS generator to generate both the PPS signal and the system clock speed
|
|
reference, and a serial port processor to read the GPS time from the
|
|
NMEA stream and to set the time value. With these external circuits, this
|
|
clock will then have sub--millisecond accuracy.
|
|
|
\chapter{Registers}\label{chap:regs}
|
\chapter{Registers}\label{chap:regs}
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This RTC clock module supports eight registers, as listed in
|
This RTC clock module supports eight registers, as listed in
|
Tbl.~\ref{tbl:reglist}. Of these eight, the first four have been so placed
|
Tbl.~\ref{tbl:reglist}. Of these eight, the first four have been so placed
|
as to be the more routine or user used registers, while the latter four are
|
as to be the more routine or user used registers, while the latter four are
|
more lower level.
|
more lower level.
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| Line 255... |
Line 283... |
HACKCNTLO&7 & 32 & R & Wall clock time.\\\hline
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HACKCNTLO&7 & 32 & R & Wall clock time.\\\hline
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\end{reglist}\caption{List of Registers}\label{tbl:reglist}
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\end{reglist}\caption{List of Registers}\label{tbl:reglist}
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\end{center}\end{table}
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\end{center}\end{table}
|
Each register will be discussed in detail in this chapter.
|
Each register will be discussed in detail in this chapter.
|
|
|
The Date module supports an additional register, listed in
|
The Date module supports its own register, listed in
|
Tbl.~\ref{tbl:datereg}.
|
Tbl.~\ref{tbl:datereg}.
|
\begin{table}[htbp]
|
\begin{table}[htbp]
|
\begin{center}
|
\begin{center}
|
\begin{reglist}
|
\begin{reglist}
|
DATE & 0 & 32 & R/W & Calendar date register\\\hline
|
DATE & 0 & 32 & R/W & Calendar date register\\\hline
|
| Line 270... |
Line 298... |
\section{Clock Time Register}
|
\section{Clock Time Register}
|
The various bit fields associated with the current time may be found in
|
The various bit fields associated with the current time may be found in
|
the {\tt CLOCK} register, shown in Tbl.~\ref{tbl:clockreg}.
|
the {\tt CLOCK} register, shown in Tbl.~\ref{tbl:clockreg}.
|
\begin{table}[htbp]\begin{center}
|
\begin{table}[htbp]\begin{center}
|
\begin{bitlist}
|
\begin{bitlist}
|
28--31 & R & Always return zero.\\\hline
|
26--31 & R & Always return zero.\\\hline
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24--27 & R/W & Seven Segment Display Mode.\\\hline
|
24--25 & R/W & Seven Segment Display Mode.\\\hline
|
22--23 & R & Always return zero.\\\hline
|
22--23 & R & Always return zero.\\\hline
|
16--21 & R/W & Current time, BCD hours\\\hline
|
16--21 & R/W & Current time, BCD hours\\\hline
|
8--15 & R/W & Current time, BCD minutes\\\hline
|
8--15 & R/W & Current time, BCD minutes\\\hline
|
0--7 & R/W & Current time, BCD seconds\\\hline
|
0--7 & R/W & Current time, BCD seconds\\\hline
|
\end{bitlist}
|
\end{bitlist}
|
| Line 287... |
Line 315... |
of the various subcomponent registers will set that register, unless the
|
of the various subcomponent registers will set that register, unless the
|
write value is a 8'hff. The behaviour of the clock when non--decimal
|
write value is a 8'hff. The behaviour of the clock when non--decimal
|
values are written, other than all F's, is undefined.
|
values are written, other than all F's, is undefined.
|
|
|
Separate from the time, however, is the seven segment display mode. Four
|
Separate from the time, however, is the seven segment display mode. Four
|
values are currently supported: 4'h0 to display the hours and minutes,
|
values are currently supported: 2'h0 to display the hours and minutes,
|
4'h1 to display the timer in minutes and seconds, 4'h2 to display the
|
2'h1 to display the timer in minutes and seconds, 2'h2 to display the
|
stopwatch in lower order minutes, seconds, and sixteenths of a second, and
|
stopwatch in lower order minutes, seconds, and sixteenths of a second, and
|
4'h3 to display the minutes and seconds of the current time. In all cases,
|
2'h3 to display the minutes and seconds of the current time. In all cases,
|
the decimal point will appear to the right of the lowest order digit
|
the decimal point will appear to the right of the lowest order digit
|
and will blink with the second hand. That is, the decimal will be high for
|
and will blink with the second hand. That is, the decimal will be high for
|
the second half of any second, and low at the top of the second.
|
the second half of any second, and low at the top of the second.
|
|
|
|
In the case of the RTC light, the seven segment display controller bits have
|
|
been wired to zeros.
|
|
|
|
In the case of the RTC modified for GPS, the most significant bit \#31 has
|
|
been modified to produce a zero if the GPS lock signal is true, or a one
|
|
for an error condition.
|
|
|
\section{Countdown Timer Register}
|
\section{Countdown Timer Register}
|
The countdown timer register, whose bit--wise values are shown in
|
The countdown timer register, whose bit--wise values are shown in
|
Tbl.~\ref{tbl:timer},
|
Tbl.~\ref{tbl:timer},
|
\begin{table}[htbp]
|
\begin{table}[htbp]
|
\begin{center}
|
\begin{center}
|
