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demo-bode-plotter
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builtindac
Ondřej Hruška 7 years ago
parent d2651c6da7
commit c43f1dff50
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GPG Key ID: 2C5FD5035250423D
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  1. 2
      LICENSE
  2. 23
      README.md
  3. 64
      UNITS.INI

2
LICENSE
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MIT License MIT License
Copyright (c) <year> <copyright holders> Copyright (c) 2018 Ondřej Hruška
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

23
README.md
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# demo-bode-plotter # demo-bode-plotter
GEX demo measuring the amplitude and phase frequency response of analog filtes GEX demo measuring the amplitude and phase frequency response of analog filtes.
To run it, change the 'gex' symlink to point to your copy of the GEX client library. This demo uses an external waveform generador AD9833 (on a breakout module from eBay).
It could also use the built-in DAC, but the performance is sub-optimal and the plots
obtained with it had a lot of glitches. Feel free to adjust the script to use the
internal DAC and try it.
The AD9833 is connected to SPI on pins PA4 (SS), PA5 (SCK), and PA7 (MOSI).
Pins PA1 and PA2 are used by the ADC and attach before and after the filter (DUT).
The generator has a very low output amplitude (0.65 V max). To better utilize the
input range of the ADC, I used OP213 in a non-inverting configuration
(resistors 7.5k and 2.2k), with a 10M resistor from the input to GND. This gives us gain
of around 4.4, enough to reach just under 3V.
## To run the script
- Change the 'gex' symlink to point to your copy of the GEX client library.
- Load the attached UNITS.INI file into GEX (intended for GEX Hub)
- Connect the external circuitry and run the script.
Dependencies - pyplot, numpy, and whatever you need to use the GEX library: typically pyusb or pyserial.
## Example outputs ## Example outputs

64
UNITS.INI
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# remove the same way. Reload to update the unit sections below. # remove the same way. Reload to update the unit sections below.
# Digital output # Digital output
DO=areset DO=
# Digital input with triggers # Digital input with triggers
DI=psign DI=
# Neopixel RGB LED strip # Neopixel RGB LED strip
NPX= NPX=
# I2C master # I2C master
@ -25,7 +25,7 @@ ADC=adc
# Shift register driver (595, 4094) # Shift register driver (595, 4094)
SIPO= SIPO=
# Frequency and pulse measurement # Frequency and pulse measurement
FCAP=fcap FCAP=
# Capacitive touch sensing # Capacitive touch sensing
TOUCH= TOUCH=
# Simple PWM output # Simple PWM output
@ -33,35 +33,7 @@ PWMDIM=
# Two-channel analog output with waveforms # Two-channel analog output with waveforms
DAC= DAC=
[DO:areset@1] [SPI:spi@2]
# Port name
port=A
# Pins (comma separated, supports ranges)
pins=8
# Initially high pins
initial=8
# Open-drain pins
open-drain=
[DI:psign@2]
# Port name
port=A
# Pins (comma separated, supports ranges)
pins=3
# Pins with pull-up
pull-up=
# Pins with pull-down
pull-down=
# Trigger pins activated by rising/falling edge
trig-rise=
trig-fall=
# Trigger pins auto-armed by default
auto-trigger=
# Triggers hold-off time (ms)
hold-off=100
[SPI:spi@3]
# Peripheral number (SPIx) # Peripheral number (SPIx)
device=1 device=1
# Pin mappings (SCK,MISO,MOSI) # Pin mappings (SCK,MISO,MOSI)
@ -83,48 +55,30 @@ first-bit=MSB
# SS port name # SS port name
port=A port=A
# SS pins (comma separated, supports ranges) # SS pins (comma separated, supports ranges)
pins=14 pins=4
[ADC:adc@4] [ADC:adc@4]
# Enabled channels, comma separated # Enabled channels, comma separated
# 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 # 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
# A0 A1 A2 A3 A4 A5 A6 A7 B0 B1 C0 C1 C2 C3 C4 C5 Tsens Vref # A0 A1 A2 A3 A4 A5 A6 A7 B0 B1 C0 C1 C2 C3 C4 C5 Tsens Vref
channels=1-2, 17 channels=1-2
# Sampling time (0-7) # Sampling time (0-7)
sample_time=2 sample_time=2
# Sampling frequency (Hz) # Sampling frequency (Hz)
frequency=10000 frequency=1000
# Sample buffer size # Sample buffer size
# - shared by all enabled channels # - shared by all enabled channels
# - defines the maximum pre-trigger size (divide by # of channels) # - defines the maximum pre-trigger size (divide by # of channels)
# - captured data is sent in half-buffer chunks # - captured data is sent in half-buffer chunks
# - buffer overrun aborts the data capture # - buffer overrun aborts the data capture
buffer_size=256 buffer_size=512
# Enable continuous sampling with averaging # Enable continuous sampling with averaging
# Caution: This can cause DAC output glitches # Caution: This can cause DAC output glitches
averaging=Y averaging=N
# Exponential averaging coefficient (permil, range 0-1000 ~ 0.000-1.000) # Exponential averaging coefficient (permil, range 0-1000 ~ 0.000-1.000)
# - used formula: y[t]=(1-k)*y[t-1]+k*u[t] # - used formula: y[t]=(1-k)*y[t-1]+k*u[t]
# - not available when a capture is running # - not available when a capture is running
avg_factor=800 avg_factor=800
[FCAP:fcap@5]
# Signal input pin - one of:
# Full support: A0, A5, A15
# Indirect only: A1, B3
pin=A0
# Active level or edge (0-low,falling; 1-high,rising)
active-level=1
# Input filtering (0-15)
input-filter=0
# Pulse counter pre-divider (1,2,4,8)
direct-presc=1
# Pulse counting interval (ms)
direct-time=1000
# Mode on startup: N-none, I-indirect, D-direct, F-free count
initial-mode=N

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