Move README to README.md and update it.

README.md

@@ -0,0 +1,106 @@
+SUMP compatible logic analyzer for Arduino
+==========================================
+
+This Arduino sketch implements a SUMP protocol compatible logic analyzer.
+This implementation is compatible with the standard SUMP client as well as
+an alternative OLS client.  More recently support has been added to Sigrok.
+
+This logic analyzer for Arduino supports 6 channels consisting of digital
+pins 8-13, which are the first 6 bits (0-5) of PORTB.
+Arduino pin 13 / bit 5 is the Arduino LED, bits 6 & 7 are the crystal
+oscillator pins. Comment out CHAN5 if you don't want to use the
+LED pin for an input.
+
+On the Arduino Mega board 8 channels are supported and 7k of samples.
+Pins 22-29 (Port A) are used by default.
+
+Client Software
+===============
+
+The OLS alternative client hasn't had an official release recently so you will
+need to compile it yourself.
+
+Follow the build instructions here: https://github.com/jawi/ols
+
+
+Older details on the OLS client is available at the project page:
+https://lxtreme.nl/projects/ols/
+
+Direct link to older releases of the OLS alternative client:
+http://www.lxtreme.nl/ols/
+
+The alternative client version is highly recommended.  You can tried the older
+release ols-0.9.7.2 but most likely need to build it yourself. Use "ols-0.9.7"
+or newer for built-in device profiles.
+
+To use this with the original or alternative SUMP clients,
+use these settings:
+```
+Sampling rate: 4MHz (or lower) (no 2MHz on ATmega168)
+Channel Groups: 0 (zero) only
+Recording Size:
+   ATmega168:  532 (or lower)
+   ATmega328:  1024 (or lower)
+   ATmega2560: 7168 (or lower)
+Noise Filter: doesn't matter
+RLE: disabled (unchecked)
+```
+
+Using the Logic Analyzer
+========================
+Triggering is still a work in progress, but generally works for samples
+below 1MHz.  1MHz works for a basic busy wait trigger that doesn't store
+until after the trigger fires.
+
+Please try it out and report back.  Please provide a detailed bug report
+if you file an issue.
+
+Debugging
+=========
+
+You can uncomment the `#define DEBUG_MENU` line to add some diagnostic menu
+options for capturing or dumping the capture buffer.
+You can uncomment the `#define DEBUG` and `#define DEBUG_MENU` for a couple
+extra menu options and logging of the received commands.  The DEBUG option
+is generally only useful for development, while the DEBUG_MENU option is
+good for troubleshooting when the logic_analyzer sketch isn't working for you.
+Both are disabled by default to conserve RAM for improved stability.
+
+CLI compiling
+=============
+
+If you want to use the `arduino-cli` tool to compile this using the Makefile,
+you'll need to install the tool first following instructions here:
+https://arduino.github.io/arduino-cli/
+
+Once installed you can simple type `make` and you should get some simple help:
+```bash
+$ make
+---> run 'make build' to compile for Arduino Duemilanove
+---> run 'make upload' to upload to /dev/ttyUSB*
+```
+
+
+Other Notes
+===========================================================================
+```
+NOTE: Starting with v0.11 you can sample at 4MHz & 2MHz rates in addition to the 
+      previous 1MHz and lower rates.  This is done via unrolled loops which
+      makes the source code huge and the binary takes much more of the flash.
+      v0.11 is just slightly too big for an ATmega168's flash. The code 
+      automatically skips the 2MHz code on ATmega168
+
+NOTE: v0.09 switched the channels BACK to pins 8-13 for trigger reliability.
+      Please report any issues.  Uncomment USE_PORTD for pins 2-7.
+
+NOTE: If you are using the original SUMP client, then you will get a
+      "device not found" error.
+      You must DISABLE the Arduino auto reset feature to use this logic analyzer
+      code. There are various methods to do this, some boards have a jumper,
+      others require you to cut a trace.  You may also install a *precisely*
+      120 Ohm resistor between the reset & 5V piins.  Make sure it is really
+      120 Ohm or you may damage your board.  It is much easier to use the
+      alternative SUMP client referenced above.
+      [ This is not needed with ols-0.9.7 or newer. ]
+      [ DO NOT use this resistor unless absolutely necessary on old clients. ]
+```