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Midibox design and construction notes

Entries in this blog

How to Offset and Scale an Analog Input

When interfacing a Joystick, Modwheel or Pitchbender it is sometimes found that the voltage range on the potentiometer output is well inside the range of the Core ADC input.   This can often be overcome with digital calibration in the firmware (e.g MIDIbox KB) in some cases there is extreme loss of resolution.   Presented here is a circuit to overcome this to give the ADC the full range (in this case 0..3.3V) even though the range of the potentiometer is well inside this.

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4 Midi IN/OUT Ports for SEQV4L (Adding 2 more MIDI I/O)

Abstract This article documents the hardware and software mods to provide 2 extra (4 total) Midi I/O ports on the MB SEQ4L. The added ports use the onboard UARTs (2,3) of the LPC MIOS32 core. The underlying sequencer code supports these ports (MIDI 3 and 4), but in the case of MIDI 3, the pins used, need to be replaced as they are( were) used to drive LED matrix columns. I chose J28 to provide these LED column driver pins, unfortunately they are part of the CV output (which I don't want) w

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Signal Integrity for long SRIO chains (MIOS32)

Abstract Discussion of the problems limiting the length of SRIO chains. Some causes of signal integrity problems in transmission lines are mentioned. A Working solution is presented. Introduction The problems limiting the length (physical length and the number of chips connected) of DOUT shift registers has been canvassed during the development of my Midi Keyboard LED Display (MKLD) project. MKLD Itself is the subject of an upcoming blog article. Suffice it to say for now that the

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MIOS32: Velocity crossfaded keyboard zones (code included)

Simple keyboard zones Rather than have the whole keyboard output the same midi channel (hence same sound) we may want to have "left hand ->Bass" and "right hand -> Treble" parts. This is accomplished by having a "zones" in this case upper and lower parts of the keyboard separated at a certain note on the keyboard ("split point"). A simple keyboard zone split is simple to define: for example output note numbers above a the split point on a different channel. Velocity crossfad

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Getting Open OCD working with Amontec JTAG Key (WinXP)

This is what worked for me: 1) Download and install openocd 0.2.0 (earliest version after 0.1.0 available as prebuilt *.msi. Btw, 0.1.0 is preferred for compatibility with the mios provided scripts) 2) In Program Files\OpenOCD\0.2.0\drivers is a folder contained in ft223.zip, unpack this folder to a temporary location. 3) Attach the JTAG key to USB. After "Found New Hardware" wizard, install from the location of the folder in step (2) 4) Invoke OpenOcd with the following command line:

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Connecting a CORE_STM32 to a Jaycar QP5518 Character LCD

Jaycar is an electronic component retailer in Australia. They have stores in many locations and for this reason are a convenient source of parts. The QP5518 (Jaycar's cat. number) is 2x16 yel/grn LED backlit display. It is pin compatible with the Core32 EXCEPT VDD AND VSS NEED TO BE SWAPPED. Why this is the case I have no idea, but it's sure to bring some to grief. FIX: Simply peal back wires 1,2 of the ribbon used and twist it before crimping the IDC connector at one end. Thats Brown

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