feat: allow user to use all 8 channels on PmodDA4

pynq/lib/pmod/pmod_dac.py

@@ -24,6 +24,15 @@ class Pmod_DAC(object):
 
     """
 
+    CHANNEL_A = 0
+    CHANNEL_B = 1
+    CHANNEL_C = 2
+    CHANNEL_D = 3
+    CHANNEL_E = 4
+    CHANNEL_F = 5
+    CHANNEL_G = 6
+    CHANNEL_H = 7
+
     def __init__(self, mb_info, value=None):
         """Return a new instance of a DAC object.
 
@@ -43,17 +52,20 @@ def __init__(self, mb_info, value=None):
         if value:
             self.write(value)
 
-    def write(self, value):
+    def write(self, value, channel=0):
         """Write a floating point number onto the DAC Pmod.
 
         Note
         ----
         Input value must be in the range [0.00, 2.50] 
+        Input channel must be an integer in the range [0, 7]
 
         Parameters
         ----------
         value : float
             The value to be written to the DAC.
+        channel : int
+            The channel to write on to the DAC.
 
         Returns
         -------
@@ -63,9 +75,10 @@ def write(self, value):
         if not 0.00 <= value <= 2.5:
             raise ValueError("Requested value not in range [0.00, 2.50].")
 
+        if not 0 <= channel <= 7:
+            raise ValueError("Requested channel not in range [0, 7].")
+
         # Calculate the voltage value and write to DAC
-        int_val = int(value / 0.0006105)
-        cmd = (int_val << 20) | FIXEDGEN
+        int_val = int(value * 1638)
+        cmd = (int_val << 20) | (channel << 16) | FIXEDGEN
         self.microblaze.write_blocking_command(cmd)
-
-