1wire search support

gex/PayloadParser.py

@@ -27,6 +27,10 @@ class PayloadParser:
         self.ptr += n
         return slice
 
+    def length(self) -> int:
+        """ Measure the tail """
+        return len(self.buf) - self.ptr
+
     def rewind(self):
         """ Reset the slice pointer to the beginning """
         self.ptr = 0

gex/units/OneWire.py

@@ -8,5 +8,61 @@ class OneWire(gex.Unit):
     def _type(self):
         return '1WIRE'
 
-    def test(self):
-        return self._query(0x00)
+    def test_presence(self):
+        """ Test presence fo any 1wire devices on the bus """
+        resp = self._query(0)
+        pp = gex.PayloadParser(resp)
+        return pp.bool()
+
+    def read_address(self, as_array=False):
+        """ Read the address of a lone device on the bus """
+        resp = self._query(4)
+        pp = gex.PayloadParser(resp)
+        if as_array:
+            return list(pp.tail())
+        else:
+            return pp.u64()
+
+    def search(self, alarm=False):
+        """ Find all devices, or devices with alarm """
+        devices = []
+
+        resp = self._query(2 if alarm else 1)
+        hasmore = True
+        while hasmore:
+            pp = gex.PayloadParser(resp)
+            hasmore = pp.bool()
+            while pp.length() > 0:
+                devices.append(pp.u64())
+
+            if hasmore:
+                resp = self._query(3)
+
+        return devices
+
+    def query(self, request, rcount, addr=None, as_array=False):
+        """ Query a device """
+        pb = gex.PayloadBuilder()
+        if addr is not None:
+            pb.u64(addr)
+
+        pb.u16(rcount)
+
+        pb.blob(request)
+
+        resp = self._query(11 if addr is None else 13, pb.close())
+        return resp.data if not as_array else list(resp.data)
+
+    def write(self, payload, addr=None, confirm=True):
+        """ Write to a device """
+        pb = gex.PayloadBuilder()
+        if addr is not None:
+            pb.u64(addr)
+
+        pb.blob(payload)
+
+        self._send(10 if addr is None else 12, pb.close(), confirm=confirm)
+
+    def wait_ready(self):
+        """ Wait for DS18x20 to complete measurement (or other chip using the same polling mechanism) """
+        self._query(20)

main.py

@@ -12,15 +12,55 @@ with gex.Client(transport) as client:
         print(s)
         client.ini_write(s)
 
+    # search the bus
+    if False:
+        ow = gex.OneWire(client, 'ow')
+        print("Presence: ", ow.test_presence())
+        print("Devices:", ow.search())
+
+    # search the bus for alarm
+    if False:
+        ow = gex.OneWire(client, 'ow')
+        print("Presence: ", ow.test_presence())
+        print("Devices w alarm:", ow.search(alarm=True))
+
+    # simple 1w check
     if True:
         ow = gex.OneWire(client, 'ow')
-        resp = ow.test()
-        print(resp)
+        print("Presence: ", ow.test_presence())
+        print("ROM: 0x%016x" % ow.read_address())
+        print("Scratch:", ow.query([0xBE], 9, as_array=True))
+
+    # testing ds1820 temp meas without polling
+    if False:
+        ow = gex.OneWire(client, 'ow')
+        print("Presence: ", ow.test_presence())
+        print("Starting measure...")
+        ow.write([0x44])
+        time.sleep(1)
+        print("Scratch:", ow.query([0xBE], 9))
+
+    # testing ds1820 temp meas with polling
+    if True:
+        ow = gex.OneWire(client, 'ow')
+        print("Presence: ", ow.test_presence())
+        print("Starting measure...")
+        ow.write([0x44])
+        ow.wait_ready()
+        data = ow.query([0xBE], 9)
+
+        pp = gex.PayloadParser(data)
+
+        temp = pp.i16()/2.0
+        th = pp.i8()
+        tl = pp.i8()
+        reserved = pp.i16()
+        remain = float(pp.u8())
+        perc = float(pp.u8())
+
+        realtemp = temp - 0.25+(perc-remain)/perc
+        print("Temperature = %f °C (th %d, tl %d)" % (realtemp, th, tl))
 
-        pp = gex.PayloadParser(resp.data)
-        print("Temperature   %f" % (pp.i16()/2))
-        print("Count_remain  %d" % pp.u8())
-        print("Count_per_deg %d" % pp.u8())
 
     if False:
         buf = client.bulk_read(gex.MSG_INI_READ)