1 files changed, 122 insertions, 0 deletions
diff --git a/doc/measure_spectrum.py b/doc/measure_spectrum.py
new file mode 100644
index 0000000..70f4e9b
--- /dev/null
+++ b/doc/measure_spectrum.py
@@ -0,0 +1,122 @@
+#!/usr/bin/env python3
+
+import time
+import statistics
+import sqlite3
+from datetime import datetime
+
+from pyBusPirateLite import BitBang
+
+if __name__ == '__main__':
+    import argparse
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-s', '--steps', type=int, nargs='?', default=400, help='Steps to run through')
+    parser.add_argument('-k', '--skip', type=int, nargs='?', default=2, help='Steps skip between measurements for shorter runtime')
+    parser.add_argument('-d', '--database', default='spectra.sqlite3', help='sqlite3 database file to store results in')
+    parser.add_argument('-w', '--wait', type=float, default=2.0, help='time to wait between samples in seconds')
+    parser.add_argument('-o', '--oversample', type=int, default=32, help='oversampling ratio')
+    parser.add_argument('-g', '--gain', type=float, default=None, help='Transimpedance gain of amplifier in MOhm')
+    parser.add_argument('-c', '--comment', help='run comment')
+    parser.add_argument('-p', '--port', default='/dev/serial/by-id/usb-FTDI_FT232R_USB_UART_AD01W1RF-if00-port0', help='Serial port device of the control buspirate')
+    parser.add_argument('run_name', nargs='?', default='auto')
+    parser.add_argument('color', help='Captured color channel')
+    args = parser.parse_args()
+
+    db = sqlite3.connect(args.database)
+    db.execute("""
+        CREATE TABLE IF NOT EXISTS runs (
+                capture_id INTEGER PRIMARY KEY,
+                name TEXT,
+                comment TEXT,
+                color TEXT, -- Captured color channel
+                gain REAL, -- Preamplifier transimpedance in Ohms
+                timestamp REAL -- unix timestamp in fractional seconds
+                )""")
+    db.execute("""
+        CREATE TABLE IF NOT EXISTS measurements (
+                measurement_id INTEGER PRIMARY KEY,
+                capture_id INTEGER,
+                led_on INTEGER,
+                step INTEGER,
+                voltage REAL, -- volts
+                voltage_stdev REAL, -- volts
+                timestamp REAL, -- unix timestamp in fractional seconds
+                FOREIGN KEY (capture_id) REFERENCES runs)""")
+
+    class BPState:
+        def __init__(self, port):
+            self.bp = BitBang(port)
+            self._led = 0
+            self._stepper_dir = 'down'
+            self.reinit()
+
+        def reinit(self):
+            self.bp.enter_bb()
+            self.led(self._led)
+            self.stepper_direction(self._stepper_dir)
+            self.bp.cs = 0
+
+        def led(self, st):
+            self._led = st
+            self.bp.mosi = st
+
+        def stepper_direction(self, direction):
+            self._stepper_dir = direction
+            self.bp.aux = 0 if direction == 'down' else 1
+
+        def step(self):
+            self.bp.cs = 1
+            time.sleep(0.005)
+            self.bp.cs = 0
+            time.sleep(0.005)
+
+        def adc(self, oversampling):
+            self.reinit()
+            return [ self.bp.adc_value for _ in range(oversampling) ]
+
+    bp = BPState(args.port)
+
+    with db:
+        cur = db.cursor()
+        cur.execute('INSERT INTO runs(name, comment, color, gain, timestamp) VALUES (?, ?, ?, ?, ?)',
+                (args.run_name, args.comment, args.color, args.gain*1e6, time.time()))
+        capture_id = cur.lastrowid
+
+    print('Starting capture {} "{}" at {:%y-%m-%d %H:%M:%S:%f}'.format(capture_id, args.run_name, datetime.now()))
+    print('[measurement id] " " [step number] " " [reading (V)]')
+
+    bp.stepper_direction('down')
+    for _ in range(10):
+        bp.step()
+
+    bp.stepper_direction('up')
+    for step in range(0, args.steps+args.skip, args.skip): # Run one skip past end to capture both interval boundaries
+        for led_val in [1]: # This can be used for self-calibration.
+            try:
+                bp.led(led_val)
+                time.sleep(args.wait)
+
+                readings = bp.adc(args.oversample)
+                mean, stdev = statistics.mean(readings), statistics.stdev(readings)
+
+                with db:
+                    cur = db.cursor()
+                    cur.execute('''
+                        INSERT INTO measurements (
+                                capture_id, led_on, step, voltage, voltage_stdev, timestamp
+                            ) VALUES (?, ?, ?, ?, ?, ?)''',
+                            (capture_id, led_val, step, mean, stdev, time.time()))
+                    print('{:08d} {:03} {}: {:5.4f} stdev {:5.4f}'.format(
+                        cur.lastrowid, step, led_val, mean, stdev))
+            except KeyboardInterrupt:
+                raise
+            except TypeError as e:
+                print('Buspirate hiccup, ignoring:', e)
+        for _ in range(args.skip):
+            bp.step()
+
+    bp.stepper_direction('down')
+    for _ in range(args.steps+args.skip):
+        bp.step()
+