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prod/doc/: cleanup and clarifications after proofreading

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This commit is contained in:
Werner Almesberger 2011-05-29 10:37:17 -03:00
parent 8b26bb7130
commit 46b15effa9
5 changed files with 52 additions and 30 deletions
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27
prod/doc/analysis.hmac
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@ -106,7 +106,8 @@ components as shown in this table:
</TABLE>
<P>
Ground can be accessed at the cover of the crystal.
Note that the fiducials are not connected to ground.
Note that the fiducials, while looking like test points,
are not connected to anything.
<P>
This image shows the location of the measurement points:
<P>
@ -131,7 +132,7 @@ components as shown in this table:
<P>
Ground can be accessed at the cover of the crystal, at the shield of the
USB connector, or at the test point P11.
Note that the fiducials are not connected to ground.
Note that the fiducials are not connected to anything.
<P>
This image shows the location of the measurement points:
<P>
@ -144,9 +145,15 @@ This image shows the location of the measurement points:
<SECTION ref="clock" title="Clock frequency">
The precision of the crystal oscillator is crucial for
operation. Anomalies are easy to detect with even a low-cost oscilloscope
and pinpoint specific problems and help to select further analysis steps.
<P>
operation. Anomalies are easy to detect with even a low-cost oscilloscope.
This can pinpoint specific problems and help to select further analysis steps.
<!-- ---------------------------------------------------------------------- -->
<SUBSECTION title="Oscillator tolerances">
The crystal used in <B>atben</B> and <B>atusb</B> has a nominal tolerance
of +/&minus; 15 ppm at 22-28 C. Low-cost oscilloscopes typically have a timing
accuracy of
@ -154,8 +161,12 @@ accuracy of
measuring the clock output with such an instrument. Full-speed USB only
requires an accuracy of +/&minus; 2500 ppm.
We can therefore consider all results within a range of +/&minus; 1000 ppm as
sufficient, and perform more precise measurements by other means. This
sufficient for an initial assessment, and perform more precise measurements
by other means. This
applies to <B>atben</B> as well as to <B>atusb</B>.
<P>
IEEE 802.15.4 requires the transceiver frequency to be accurate
within +/&minus; 40 ppm.
<!-- ---------------------------------------------------------------------- -->
@ -197,7 +208,7 @@ the right:
The transceiver provides the clock for the microcontroller in <B>atusb</B>.
A clock signal is therefore always available. Immediately after reset,
the transceiver generates a 1 MHz clock. When the microcontrolled comes out
the transceiver generates a 1 MHz clock. When the microcontroller comes out
of reset, it raises the transceiver's clock output to 8 MHz and then
enables USB.
<P>
@ -222,7 +233,7 @@ filter.
<TR><TD>0.999-1.001 MHz, ~3.3 Vpp<TD>Check presence of firmware; check for
shorts on SPI signals; check connectivity of SPI signals
<TR><TD>7.992-8.008 MHz, ~3.3 Vpp<TD>Perform precision measurement with
atrf-xtal
atrf-xtal (@@@)
<TR><TD>Other<TD>Check voltages; check for contamination around crystal
</TABLE>
<P>

2
prod/doc/flash.hmac
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@ -56,7 +56,7 @@ To flash the boot loader,
<A href="atusb-programming.jpg"><IMG
src="atusb-programming.jpg" width="250"></A>
<P>
<LI>finally, run
<LI>finally, <SAMP>cd</SAMP> to <SAMP>ben-wpan/prod/</SAMP> and run
<PRE>
make flash
</PRE>

12
prod/doc/index.hmac
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@ -32,8 +32,8 @@ actual testing.
The testing serves two purposes:
<OL>
<LI>Ascertain the correctness of the preceding production steps, and
<LI>identify suffering from random production flaws and either discard
them or prepare them for repair.
<LI>identify boards suffering from random production flaws and either
discard them or prepare them for repair.
</OL>
The results of testing and fault analysis also provide feedback for the
SMT process and steps preceding it.
@ -43,7 +43,7 @@ The following diagram illustrates the workflow:
<IMG src="flow.png">
<P>
Only <B>atusb</B> boards contain firmware and need flashing (which is
a two-step process, see below). The functional tests and further fault
a two-step process, see below). The functional tests and fault
analysis are largely the same for <B>atben</B> and <B>atusb</B>.
<P>
Devices accepted for further use can then be packaged for shipping.
@ -69,13 +69,15 @@ Defective devices can be discarded or retained for a deeper analysis.
three roles, with the board in its 8:10 card slot changed as
the role requires.
<DT><B><I>PC</I></B></DT>
<DD>a device capable of connecting to a Ben via USB, and of hosting an
<DD>a device running Linux. Capable of connecting to a Ben via USB, and
of hosting an
<B>atusb</B> board. In the production process, a PC can perform three
different roles:
<OL>
<LI> Host an <B>atusb</B> board acting as DUT
<LI> Host an <B>atusb</B> board acting as reference
<LI> Control a Ben via USB (for convenience)
<LI> Control a Ben via USB (for convenience and to coordinate tests
involving a sender and a receiver)
</OL>
In this document, we assume that a single PC is used in all
three roles, with one USB host port permanently connecting to the

28
prod/doc/setup.hmac
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@ -37,7 +37,7 @@ and configuration process.
<SECTION ref="pcsw" title="PC software installation">
For a DUT and reference device role, the ben-wpan utilities
For a DUT and reference device role, the ben-wpan tools
and the test scripts have to be installed on the PC. For flashing the
<B>atusb</B> application
firmware, also dfu-util and the firmware binary are required.
@ -131,8 +131,8 @@ Instructions for building the binary from sources are
<SUBSECTION title="Register Ben host name">
To simplify accessing the Ben via TCP/IP, its IP address should be
registered in the hosts file on the PC. If the Ben is running OpenWrt,
use the following command:
registered in the <SAMP>/etc/hosts</SAMP> file on the PC. If the Ben is
running OpenWrt, use the following command:
<PRE>
echo 192.168.254.101 ben >>/etc/hosts
</PRE>
@ -235,7 +235,7 @@ Finally, upload the tools to the Ben and install them under
<SAMP>/usr/bin/</SAMP> with
<PRE>
make HOST=ben install
make HOST=ben upload
</PRE>
Where <SAMP>ben</SAMP> is the host name or IP address assigned to the Ben.
@ -248,7 +248,7 @@ Where <SAMP>ben</SAMP> is the host name or IP address assigned to the Ben.
The <B>atusb</B> boot loader is flashed using avrdude. A pre-compiled
static binary (suitable for OpenWrt and Jlime) can be installed by running
the following two command on the Ben:
the following two commands on the Ben:
<PRE>
wget http://downloads.qi-hardware.com/people/werner/wpan/bindist/avrdude-5.10-de72af351f661b538add81cbc9965278a2f8c40c.tar.gz
@ -282,8 +282,8 @@ Instructions for building the binary from sources are
<SECTION ref="bensys" title="Ben system setup">
The configuration setting described in this section are lost on each
reset or reboot and either need to be entered again. Alternatively,
The configuration settings described in this section are lost on each
reset or reboot and need to be entered again. Alternatively,
a setup script running at boot time can be written.
@ -323,6 +323,10 @@ the place of the MMC driver. To disable it, run
<PRE>
echo spi2.0 >/sys/bus/spi/drivers/at86rf230/unbind
</PRE>
Note that the above command only has the desired effect if used
before running any of the user-space tools. If the kernel driver and
the user-space tools have already clashed over access to the board, the
driver will not unbind and a reboot is needed.
<!-- ---------------------------------------------------------------------- -->
@ -354,7 +358,8 @@ in the actual test environment.
Insert a known to be good <B>atben</B> board and run the following
command directly on the Ben to record the reference value for the
clock count with an accuracy of about +/&minus;20 ppm:
clock count with an accuracy of roughly +/&minus;20 ppm:
<PRE>
atrf-xtal 1000 >ben.xtal
</PRE>
@ -372,7 +377,7 @@ Ben, and if a stable temperature is maintained.
<SUBSECTION title="Signal strength">
The signal strength of a DUT is assesses by comparing it with
The signal strength of a DUT is assessed by comparing it with
measurements previously obtained in the same setup, with a known to
be good device taking the role of the DUT. It is therefore necessary
to establish a reference profile each time the test environment changes,
@ -391,8 +396,9 @@ make spectrum
</PRE>
Then place the devices appropriately and press <B>D</B> in the measurement
window to use the displayed spectrum as the reference. Multiple spectra
can be merged into the reference, e.g., if environmental conditions cause
significant variations. Spectra included in the reference are shown in blue.
can be merged into the reference, e.g., if unavoidable environmental
variations cause
significant changes. Spectra included in the reference are shown in blue.
<P>
After a obtaining the reference spectrum, press <B>Q</B> to exit. The
Makefile will then record the signal strength limits for an <B>atben</B>

13
prod/doc/test.hmac
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@ -29,8 +29,10 @@ the PC, insert the <B>atben</B> board into the Ben, and place both devices
at the same location and with the same orientation used when acquiring the
signal strength profile.
<P>
The two devices should be about 1 m apart, with as few metal or watery
objects between or near them as possible. Location and orientation should
The two devices should be about 1 m apart. Their vicinity should be free
from obstructions and items that can reflect or absorb RF signals. Such
items include metal chairs and human bodies.
Location and orientation should
be easily reproducible, e.g., by marking the device's edges on the table
with tape. Other transmitters in the 2.4 GHz band will interfere with
measurements and should be kept as far away and as inactive as possible.
@ -56,7 +58,8 @@ DUT and reference device roles are reversed.
<SECTION ref="procedure" title="Test procedure">
The test process is started with
The test process is started from the directory <SAMP>ben-wpan/prod/</SAMP>
with
<PRE>
make ben
</PRE>
@ -162,8 +165,8 @@ frequency-dependent anomalies.
<P>
This test depends on numerous external factors, like the exact position
and orientation of the two devices with respect to each other, and the
presence of any items that can reflect or absorb RF signals. Such items
include metal chairs and human bodies. Because of the test's sensitivity
presence of obstacles and conductive items (metal, people, etc.).
Because of the test's sensitivity
to environmental factors, the operator needs to decide when the result
represents a valid measurement and then confirm the result shown.
<P>