feat(itho-wpu): basic slave functionality

This uses the pigpio library as I'm not quite sure yet how to read this
data directly from /dev/i2c-1, without polling and high CPU usage.

itho-wpu.py

@@ -3,7 +3,10 @@
 import argparse
 import i2c_raw
 import logging
+import pigpio
+import queue
 import sys
+import threading
 
 consolelogformatter = logging.Formatter("%(asctime)-15s %(levelname)s: %(message)s")
 logger = logging.getLogger('stdout')
@@ -32,6 +35,38 @@ def parse_args():
     return args
 
 
+class I2CSlave():
+    def __init__(self, address):
+        self.address = address
+        self.pi = pigpio.pi()
+        if not self.pi.connected:
+            logger.error("not pi.connected")
+            return
+
+    def run(self, q):
+        try:
+            self.pi.bsc_i2c(self.address)
+            if self.pi.wait_for_event(pigpio.EVENT_BSC, 5):
+                s, b, d = self.pi.bsc_i2c(self.address)
+                result = None
+                if b:
+                    logger.debug(f"Received {b} bytes! Status {s}")
+                    result = [hex(c) for c in d]
+                    q.put(result)
+                else:
+                    logger.error(f"Received number of bytes was {b}")
+            else:
+                logger.error("pi.wait_for_event timed out")
+        except(KeyboardInterrupt):
+            self.close()
+        else:
+            self.close()
+
+    def close(self):
+        self.pi.bsc_i2c(0)
+        self.pi.stop()
+
+
 class I2CMaster:
     def __init__(self, address, bus):
         self.i = i2c_raw.I2CRaw(address=address, bus=bus)
@@ -56,7 +91,16 @@ if __name__ == "__main__":
     if args.loglevel:
         logger.setLevel(args.loglevel.upper())
 
+    q = queue.Queue()
+
+    slave = I2CSlave(address=0x40)
+    slave_thread = threading.Thread(target=slave.run, args=[q])
+    slave_thread.start()
+
     master = I2CMaster(address=0x41, bus=1)
     if args.action:
         master.execute_action(args.action)
     master.close()
+
+    result = q.get()
+    logger.info(f"Response: {result}")