pulsegen: Removed 'samples' parameter.

Number of samples used for creating an arbitrary waveform is now automatically adjusted.

pulsegen: Removed 'samples' parameter.
Number of samples used for creating an arbitrary waveform is now automatically adjusted.
5cafc73b · Projects · adbd3b8d · 5cafc73b
Commit 5cafc73b authored Feb 15, 2017 by Projects
Hide whitespace changes
Inline Side-by-side

Showing with 7 additions and 16 deletions

pulsegen.py software/utils/pulsegen.py +7 -16

No files found.
--- a/software/utils/pulsegen.py
+++ b/software/utils/pulsegen.py
@@ -99,13 +99,11 @@ class PulseGen:
        # clear errors
        self.ser.write(b'*CLS\r\n')

-    def pulse(self, count, freq, width, samples):
+    def pulse(self, count, freq, width):
        """ Configures the pulse burst signal.
        :param count: Number of requested pulses
        :param freq: Frequency of pulses [Hz]
        :param width: Pulse duration [s]
-        :param samples: Number of samples used to generate an arbitrary waveform,
-            if needed
        """
        # Select the way of generating pulses
        # 33250A has a limit of 1e6 pulses in a single burst. To overcome this
@@ -140,7 +138,9 @@ class PulseGen:

            # generate the string that represents the requested waveform
            duty_cycle = width / period
-            one_count = int(samples * duty_cycle)
+            # number of samples to accurately represent the signal
+            samples = min(math.ceil(10.0 * period / width), 65535)
+            one_count = math.ceil(samples * duty_cycle)
            zero_count = samples - one_count

            # generator DAC values mapping
@@ -149,14 +149,14 @@ class PulseGen:
            zero_value = b', -2047'

            # single pulse (take into account the duty cycle)
-            chunk = b'%s%s' % (zero_count * zero_value, one_count * one_value )
+            chunk = b'%s%s' % (zero_count * zero_value, one_count * one_value)
            # full waveform (repeat the pulse 'div' times)
            pattern = chunk * div

            # update all variables basing on the divider
            freq = freq / div
            count = math.ceil(count / div)
-            width = duty_cycle * period
+            width = one_count / samples * period
            # the actual number of pulses is rounded to the number of pulses in
            # the arbitrary waveform
            real_count = count * div
@@ -247,7 +247,6 @@ if __name__ == '__main__':
    count = 2000000
    freq = 2e6 # Hz
    width = 250e-9 # s
-    samples = 100 # number of samples for arbitrary waveform

    def usage():
        print('(c) CERN 2017')
@@ -261,7 +260,6 @@ if __name__ == '__main__':
        print('-c|--count=      number of requested pulses (default: %d)' % count)
        print('-f|--freq=       frequency of the pulses [Hz] (default: %G)' % freq)
        print('-w|--width=      pulse width [s] (default: %G)' % width)
-        print('-s|--samples=    arbitrary waveform samples count (default: %d)' % samples)
        print('')
        print('-h|--help        shows this information')

@@ -285,13 +283,6 @@ if __name__ == '__main__':
            device = arg
        elif opt in ('-f', '--freq'):
            freq = float(arg)
-        elif opt in ('-s', '--samples'):
-            samples = int(float(arg))
-
-            if samples > 65536:
-                print('ERROR: Samples number limit is 65536')
-                sys.exit(2)
-
        elif opt in ('-w', '--width'):
            width = float(arg)
        elif opt in ('-h', '--help'):
@@ -306,7 +297,7 @@ if __name__ == '__main__':
    try:
        gen = PulseGen(device, baud)
        gen.reset()
-        gen.pulse(count, freq, width, samples)
+        gen.pulse(count, freq, width)
        print('Signal generation started')
        gen.trigger()
        gen.wait()