added

example/manual/rs232.py

@@ -0,0 +1,100 @@
+from __future__ import generators
+
+from random import randrange
+
+from myhdl import Signal, Simulation, StopSimulation, \
+                  intbv, delay, negedge, join
+
+DURATION_9600 = int(1e9 / 9600)
+
+def rs232_tx(tx, data, duration=DURATION_9600):
+    
+    """ Simple rs232 transmitter procedure.
+
+    tx -- serial output data
+    data -- input data byte to be transmitted
+    duration -- transmit bit duration
+    
+    """
+
+    print 'TX: start bit'      
+    tx.next = 0
+    yield delay(duration)
+
+    for i in range(8):
+        print 'TX: %s' % data[i]
+        tx.next = data[i]
+        yield delay(duration)
+
+    print 'TX: stop bit'       
+    tx.next = 1
+    yield delay(duration)
+
+    
+        
+def rs232_rx(rx, data, duration=DURATION_9600, timeout=None):
+    
+    """ Simple rs232 receiver procedure.
+
+    rx -- serial input data
+    data -- data received
+    duration -- receive bit duration
+    
+    """
+
+    # wait on start bit, possibly with a timeout
+    if timeout:
+        yield negedge(rx), delay(timeout)
+        if rx == 1:
+            raise StopSimulation, "Time out error"
+    else:
+        yield negedge(rx)
+
+    # sample in the middle
+    yield delay(duration // 2)
+    print 'RX: start bit'
+
+    # receive data bits
+    for i in range(8):
+        yield delay(duration)
+        print 'RX: %s' % rx
+        data[i] = rx
+
+    # stop bit
+    yield delay(duration)
+    print 'RX: stop bit'
+
+
+
+
+def test1():
+    tx = Signal(1)
+    for i in range(1, 5):
+        print "-- Call %s --" % i
+        txData = intbv(randrange(2**8))
+        yield rs232_tx(tx, txData)
+
+        
+def test2():
+    tx = Signal(1)
+    rx = Signal(1)
+    rxData = intbv(0)
+    txData = intbv(randrange(2**8))
+    yield rs232_rx(rx, rxData, timeout=3*DURATION_9600-1), rs232_tx(tx, txData)
+    
+
+def test3():
+    tx = Signal(1)
+    rx = tx
+    rxData = intbv(0)
+    txData = intbv(randrange(2**8))
+    yield rs232_rx(rx, rxData), rs232_tx(tx, txData)
+    # yield rs232_rx(rx, rxData), rs232_tx(tx, txData)
+    # yield join(rs232_rx(rx, rxData), rs232_tx(tx, txData))
+
+Simulation(test1()).run()
+print
+Simulation(test2()).run()
+print
+Simulation(test3()).run()
+