Added initial structure for bitline measurements.

compiler/characterizer/__init__.py

@@ -8,7 +8,7 @@ from .setup_hold import *
 from .functional import *
 from .worst_case import *
 from .simulation import *
-
+from .bitline_delay import *
 
 debug.info(1,"Initializing characterizer...")
 OPTS.spice_exe = ""

compiler/characterizer/bitline_delay.py

@@ -0,0 +1,72 @@
+import sys,re,shutil
+import debug
+import tech
+import math
+from .stimuli import *
+from .trim_spice import *
+from .charutils import *
+import utils
+from globals import OPTS
+from .delay import delay
+
+class bitline_delay(delay):
+    """Functions to test for the worst case delay in a target SRAM
+
+    The current worst case determines a feasible period for the SRAM then tests
+    several bits and record the delay and differences between the bits.
+
+    """
+
+    def __init__(self, sram, spfile, corner):
+        delay.__init__(self,sram,spfile,corner)
+        self.period = 1
+        self.is_bitline_measure = True
+    
+    def create_measurement_names(self):
+        """Create measurement names. The names themselves currently define the type of measurement"""
+        #Altering the names will crash the characterizer. TODO: object orientated approach to the measurements.
+        self.bitline_meas_names = ["bl_volt", "br_volt"]
+    
+    def write_delay_measures(self):
+        """
+        Write the measure statements to quantify the bitline voltage at sense amp enable 50%.
+        """
+        self.sf.write("\n* Measure statements for delay and power\n")
+
+        # Output some comments to aid where cycles start and
+        for comment in self.cycle_comments:
+            self.sf.write("* {}\n".format(comment))
+            
+        for read_port in self.targ_read_ports:
+           self.write_bitline_measures_read_port(read_port)
+
+    def write_bitline_measures_read_port(self, port):
+        """
+        Write the measure statements to quantify the delay and power results for a read port.
+        """
+        # add measure statements for delays/slews
+        for dname in self.delay_meas_names:
+            meas_values = self.get_delay_meas_values(dname, port)
+            self.stim.gen_meas_delay(*meas_values)
+    
+    
+    def analyze(self, probe_address, probe_data, slews, loads):
+        """Measures the bitline swing of the differential bitlines (bl/br) at 50% s_en """
+        self.set_probe(probe_address, probe_data)
+        self.load=max(loads)
+        self.slew=max(slews)
+        
+        port = 0
+        bitline_swings = {}
+        self.targ_read_ports = [self.read_ports[port]]
+        self.targ_write_ports = [self.write_ports[port]]
+        debug.info(1,"Bitline swing test: corner {}".format(self.corner))
+        (success, results)=self.run_delay_simulation()
+        debug.check(success, "Bitline Failed: period {}".format(self.period))
+        for mname in self.bitline_meas_names:
+            bitline_swings[mname] = results[port][mname]
+        debug.info(1,"Bitline values (bl/br): {}".format(bitline_swings))
+        return bitline_swings
+
+        
+