coredevice: add shift register driver

artiq/coredevice/shiftreg.py

@@ -0,0 +1,36 @@
+from artiq.language.core import kernel, delay
+from artiq.language.units import us
+
+
+class ShiftReg:
+    """Driver for shift registers/latch combos connected to TTLs"""
+    kernel_invariants = {"dt", "n"}
+    
+    def __init__(self, dmgr, clk, ser, latch, n=32, dt=10*us):
+        self.core = dmgr.get("core")
+        self.clk = dmgr.get(clk)
+        self.ser = dmgr.get(ser)
+        self.latch = dmgr.get(latch)
+        self.n = n
+        self.dt = dt
+
+    @kernel
+    def set(self, data):
+        """Sets the values of the latch outputs. This does not
+        advance the timeline and the waveform is generated before
+        `now`."""
+        delay(-2*(self.n + 1)*self.dt)
+        for i in range(self.n):
+            if (data >> (self.n-i-1)) & 1 == 0:
+                self.ser.off()
+            else:
+                self.ser.on()
+            self.clk.off()
+            delay(self.dt)
+            self.clk.on()
+            delay(self.dt)
+        self.clk.off()
+        self.latch.on()
+        delay(self.dt)
+        self.latch.off()
+        delay(self.dt)