From 1ba429af1331e1f34f956d75c4b14ac481886f5a Mon Sep 17 00:00:00 2001
From: Neil Gershenfeld <gersh@cba.mit.edu>
Date: Wed, 31 Mar 2021 21:39:48 -0400
Subject: [PATCH] start comm

---
 index.html | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/index.html b/index.html
index 5385fb6..70671a5 100644
--- a/index.html
+++ b/index.html
@@ -167,3 +167,37 @@ The GPIO test measures how quickly pins can communicate with a processor core; t
 
 </table>
 </center>
+
+<br><br>
+
+<center>
+<b>Communication</b>
+</center>
+
+<p>
+
+The communication test measures how quickly two nodes can exchange messages; this is relevant for implementing real-time and high data-rate algorithms. In this, the "from" node sends a byte to the "to" node, which adds 1 to it and sends it back. This is repeated many times, and the number of round trips is divided by the total time. Twice that frequency is approximately the byte rate in one direction, and 16 times that frequency is approximately the bit rate in one direction.
+
+<center>
+<table border="1" style="text-align:center">
+
+<tr>
+<th>frequency (MHz)</th>
+<th>from</th>
+<th>link</th>
+<th>to</th>
+<th>date</th>
+</tr>
+
+<tr>
+<td>0.007</td>
+<td><a href=comm/pySerial/ring.pySerial.py>i7-8700T, Python, pySerial</a></td>
+<td>USB 2.1</td>
+<td><a href=comm/SerialUSB/ring.SerialUSB.ino>ATSAMD11C, Arduino, SerialUSB</a></td>
+<td>March 2021</td>
+</tr>
+
+</table>
+</center>
+
+<br><br>
-- 
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