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README.md

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+pxsi: parameter update over serial interface
+============================================
+
+Markus Zolliker (markus.zolliker@psi.ch)
+
+helper library for micropython on RP2040 (e.g. Arduino Nano Connect or Paspberry Pico)
+
+Code example
+------------
+
+    from pxsi import Pxsi
+    
+    # declare variables visibile over serial
+    
+    vars = Pxsi('MyBox',   # idn will be: pxsi,MyBox
+        t = 5,
+        a = 2,
+    )
+
+    # create action functions for some of the variables
+
+    def change_t(value):
+        # write here what to do when t changes
+
+    # your real code
+    
+    print(t)  # the given variables are now available in the main namesapce
+
+    while True:
+        # handle IO, wait at most 0.5 secs
+        vars.handle_io(0.5)
+        # read out sensors, do control logic here
+        # important: do not sleep here!
+
+
+Serial protocol
+---------------
+
+Commands:
+
+    name         # get value of variable name
+    name=value   # change value (value must be a valid JSON value)
+    ["name1", ["name2", value]]     # multiple commands: query name1, change name2. must be a valid JSON array
+    {"name1": null, "name2": value} # alternative form - be aware that order is not guaranteed
+
+Special command for identification
+
+    *IDN?
+
+returns:
+
+    pxsi,<idn>
+
+
+For all other commands the reply is always a JSON object:
+
+    {"name1": value1, "name2", value2}
+
+In case of an error, the result contains an item with the key "_error_" and a JSON array as value,
+listing the errors appeared.
+
+
+Hints for Arduino Nano Connect
+------------------------------
+
+For a soft reset send '\x03\x04' (Ctrl-C Ctrl-D).
+The reply will be quite some text, with the last line:
+
+    pxsi:<idn>
+