DougThompson1976

jq Cheat Sheet

jq is useful utility, but I use it infrequently and each time I have to check what was the filters syntax. This cheat sheet helps we to recall what is the expression that I need. Hopefully it would help others too. For full guide refer to the official jq manual.

All the jq you (usually) need

Given the following JSON:

DougThompson1976

Processing JSON using jq

jq is useful to slice, filter, map and transform structured json data.

Installing jq

On Mac OS

brew install jq

DougThompson1976

MongoDB Cheat Sheet

Show All Databases

show dbs

Show Current Database

DougThompson1976

ESP32 as Bluetooth Keyboard

With its built-in Bluetooth capabilities, the ESP32 can act as a Bluetooth keyboard. The below code is a minimal example of how to achieve it. It will generate the key strokes for a message whenever a button attached to the ESP32 is pressed.

For the example setup, a momentary button should be connected to pin 2 and to ground. Pin 2 will be configured as an input with pull-up.

In order to receive the message, add the ESP32 as a Bluetooth keyboard of your computer or mobile phone:

1. Go to your computers/phones settings
2. Ensure Bluetooth is turned on

DougThompson1976

#8 note polyphony gated synth setup program
#by Robin Newman, August 2017
#Set initial states for polyphonic synth
set :vm1,0
set :vm2,0
set :vm3,0
set :vm4,0
set :vm5,0
set :vm6,0
set :vm7,0

DougThompson1976

# Sonic Pi Sequencer (beta)
# Not yet music, but a proof of concept and part of a toolbox to
# create pattern based music

# Rather than think about durations and time distances I'd like to think of
# bars and patterns. Something like that:

# | 16       | 1 | e | u | e | 2 | e | u | e | 3 | e | u | e | 4 | e | u | e |
# |----------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---|
# | Bass     | x |   | x | x |   |   | x |   |   | x |   |   |   |   | x |   |

DougThompson1976

# Sonic Pi Sequencer (v2)
# Simplified notation of synth lines, can now play chords

use_debug false
set_volume! 1
use_bpm 120 # beat = quarter note

# TODO

# Make 'play_rhythm_bar' to work with an array of samples like 'play_melody_bar'

DougThompson1976

# AFX Song Sketch
use_debug false
set_volume! 1
use_bpm 128 # beat = quarter note

# TODO

# Shaker
# Rework the tune synth
# Break at 19

DougThompson1976

# AFX 1.7, prepare the tune

use_debug false
set_volume! 1
use_bpm 128

load_samples [:loop_compus, :elec_wood, :drum_bass_hard, :drum_snare_hard, :drum_snare_hard, :drum_cymbal_closed, :elec_snare, :drum_tom_hi_soft]

# Helper Functions

DougThompson1976

# AFX 1.7, play the tune

use_debug false
set_volume! 1
use_bpm 128

puts "01"
mod_shaker
mod_bordun
sleep 16