takashi kadono / Mbed OS Nucleo_446

Color Oled(SSD1331) connect to STMicroelectronics Nucleo-F466

Dependencies:   ssd1331

mbed-os/tools/dev/dsp_fir.py@3:f3764f852aa8, 2018-10-11 (annotated)

Committer:
kadonotakashi
Date:
Thu Oct 11 02:27:46 2018 +0000
Revision:
3:f3764f852aa8
Parent:
0:8fdf9a60065b 
Nucreo 446 + SSD1331 test version;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
kadonotakashi 0:8fdf9a60065b 1 """
kadonotakashi 0:8fdf9a60065b 2 mbed SDK
kadonotakashi 0:8fdf9a60065b 3 Copyright (c) 2011-2013 ARM Limited
kadonotakashi 0:8fdf9a60065b 4
kadonotakashi 0:8fdf9a60065b 5 Licensed under the Apache License, Version 2.0 (the "License");
kadonotakashi 0:8fdf9a60065b 6 you may not use this file except in compliance with the License.
kadonotakashi 0:8fdf9a60065b 7 You may obtain a copy of the License at
kadonotakashi 0:8fdf9a60065b 8
kadonotakashi 0:8fdf9a60065b 9 http://www.apache.org/licenses/LICENSE-2.0
kadonotakashi 0:8fdf9a60065b 10
kadonotakashi 0:8fdf9a60065b 11 Unless required by applicable law or agreed to in writing, software
kadonotakashi 0:8fdf9a60065b 12 distributed under the License is distributed on an "AS IS" BASIS,
kadonotakashi 0:8fdf9a60065b 13 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
kadonotakashi 0:8fdf9a60065b 14 See the License for the specific language governing permissions and
kadonotakashi 0:8fdf9a60065b 15 limitations under the License.
kadonotakashi 0:8fdf9a60065b 16 """
kadonotakashi 0:8fdf9a60065b 17 from numpy import sin, arange, pi
kadonotakashi 0:8fdf9a60065b 18 from scipy.signal import lfilter, firwin
kadonotakashi 0:8fdf9a60065b 19 from pylab import figure, plot, grid, show
kadonotakashi 0:8fdf9a60065b 20
kadonotakashi 0:8fdf9a60065b 21 #------------------------------------------------
kadonotakashi 0:8fdf9a60065b 22 # Create a signal for demonstration.
kadonotakashi 0:8fdf9a60065b 23 #------------------------------------------------
kadonotakashi 0:8fdf9a60065b 24 # 320 samples of (1000Hz + 15000 Hz) at 48 kHz
kadonotakashi 0:8fdf9a60065b 25 sample_rate = 48000.
kadonotakashi 0:8fdf9a60065b 26 nsamples = 320
kadonotakashi 0:8fdf9a60065b 27
kadonotakashi 0:8fdf9a60065b 28 F_1KHz = 1000.
kadonotakashi 0:8fdf9a60065b 29 A_1KHz = 1.0
kadonotakashi 0:8fdf9a60065b 30
kadonotakashi 0:8fdf9a60065b 31 F_15KHz = 15000.
kadonotakashi 0:8fdf9a60065b 32 A_15KHz = 0.5
kadonotakashi 0:8fdf9a60065b 33
kadonotakashi 0:8fdf9a60065b 34 t = arange(nsamples) / sample_rate
kadonotakashi 0:8fdf9a60065b 35 signal = A_1KHz * sin(2*pi*F_1KHz*t) + A_15KHz*sin(2*pi*F_15KHz*t)
kadonotakashi 0:8fdf9a60065b 36
kadonotakashi 0:8fdf9a60065b 37 #------------------------------------------------
kadonotakashi 0:8fdf9a60065b 38 # Create a FIR filter and apply it to signal.
kadonotakashi 0:8fdf9a60065b 39 #------------------------------------------------
kadonotakashi 0:8fdf9a60065b 40 # The Nyquist rate of the signal.
kadonotakashi 0:8fdf9a60065b 41 nyq_rate = sample_rate / 2.
kadonotakashi 0:8fdf9a60065b 42
kadonotakashi 0:8fdf9a60065b 43 # The cutoff frequency of the filter: 6KHz
kadonotakashi 0:8fdf9a60065b 44 cutoff_hz = 6000.0
kadonotakashi 0:8fdf9a60065b 45
kadonotakashi 0:8fdf9a60065b 46 # Length of the filter (number of coefficients, i.e. the filter order + 1)
kadonotakashi 0:8fdf9a60065b 47 numtaps = 29
kadonotakashi 0:8fdf9a60065b 48
kadonotakashi 0:8fdf9a60065b 49 # Use firwin to create a lowpass FIR filter
kadonotakashi 0:8fdf9a60065b 50 fir_coeff = firwin(numtaps, cutoff_hz/nyq_rate)
kadonotakashi 0:8fdf9a60065b 51
kadonotakashi 0:8fdf9a60065b 52 # Use lfilter to filter the signal with the FIR filter
kadonotakashi 0:8fdf9a60065b 53 filtered_signal = lfilter(fir_coeff, 1.0, signal)
kadonotakashi 0:8fdf9a60065b 54
kadonotakashi 0:8fdf9a60065b 55 #------------------------------------------------
kadonotakashi 0:8fdf9a60065b 56 # Plot the original and filtered signals.
kadonotakashi 0:8fdf9a60065b 57 #------------------------------------------------
kadonotakashi 0:8fdf9a60065b 58
kadonotakashi 0:8fdf9a60065b 59 # The first N-1 samples are "corrupted" by the initial conditions
kadonotakashi 0:8fdf9a60065b 60 warmup = numtaps - 1
kadonotakashi 0:8fdf9a60065b 61
kadonotakashi 0:8fdf9a60065b 62 # The phase delay of the filtered signal
kadonotakashi 0:8fdf9a60065b 63 delay = (warmup / 2) / sample_rate
kadonotakashi 0:8fdf9a60065b 64
kadonotakashi 0:8fdf9a60065b 65 figure(1)
kadonotakashi 0:8fdf9a60065b 66 # Plot the original signal
kadonotakashi 0:8fdf9a60065b 67 plot(t, signal)
kadonotakashi 0:8fdf9a60065b 68
kadonotakashi 0:8fdf9a60065b 69 # Plot the filtered signal, shifted to compensate for the phase delay
kadonotakashi 0:8fdf9a60065b 70 plot(t-delay, filtered_signal, 'r-')
kadonotakashi 0:8fdf9a60065b 71
kadonotakashi 0:8fdf9a60065b 72 # Plot just the "good" part of the filtered signal. The first N-1
kadonotakashi 0:8fdf9a60065b 73 # samples are "corrupted" by the initial conditions.
kadonotakashi 0:8fdf9a60065b 74 plot(t[warmup:]-delay, filtered_signal[warmup:], 'g', linewidth=4)
kadonotakashi 0:8fdf9a60065b 75
kadonotakashi 0:8fdf9a60065b 76 grid(True)
kadonotakashi 0:8fdf9a60065b 77
kadonotakashi 0:8fdf9a60065b 78 show()
kadonotakashi 0:8fdf9a60065b 79
kadonotakashi 0:8fdf9a60065b 80 #------------------------------------------------
kadonotakashi 0:8fdf9a60065b 81 # Print values
kadonotakashi 0:8fdf9a60065b 82 #------------------------------------------------
kadonotakashi 0:8fdf9a60065b 83 def print_values(label, values):
kadonotakashi 0:8fdf9a60065b 84 var = "float32_t %s[%d]" % (label, len(values))
kadonotakashi 0:8fdf9a60065b 85 print "%-30s = {%s}" % (var, ', '.join(["%+.10f" % x for x in values]))
kadonotakashi 0:8fdf9a60065b 86
kadonotakashi 0:8fdf9a60065b 87 print_values('signal', signal)
kadonotakashi 0:8fdf9a60065b 88 print_values('fir_coeff', fir_coeff)
kadonotakashi 0:8fdf9a60065b 89 print_values('filtered_signal', filtered_signal)