MIDI-Encoder
Author: R.J. Maris
(preliminary presentation)
Originally, this project has been realized with a PIC-target by J.D.
Petkov (project
page). In order to obtain more flexibility in customizing the
function for any variety of keyboard matrix organizations, the
project has been written entirely new for the MSP430. This was
established by using the FET-evaluation kit for the MSP430F149.
Currently the project is still realized as a prototype consisting of
a breadboard with the FET-kit stacked on top of it (see photograph).
One of the next steps is a realization with a hobbyist-friendly
breadboard solution using the 28-pin MSP430F122.
Project description
The keyboard used here has 61 keys organized as a matrix of 6x10. The
photograph shows part of the diode network soldered on the row bus
using thin speedwire. The speedwire provides a laque isolation which
can be melted on solder locations. Therefore no additional isolation
on the diode terminals is necessary.
Here the keyboard together with the prototype can be viewed.
On top left of the evaluation board, the JTAG connector can be seen.
The only additional hardware consists of resistors, resistor packs
and a FET transistor. The transistor served an inverter function in
order to create test output to an RS232-input of a computer.
The cable to the PC-soundcard is not shown here. Actually, this is a
round cable which also carries the supply current for the encoder
application. Current consumption is no more than approx. 2mA, mainly
due to the crystal oscillator.
Software
The software is written using the IAR-compiler and currently measures
approx. 1Kbyte binary code. The biggest part of the software is
established by the keyboard scan & debounce functions. The
download version represents the first tested version. This will be
updated soon.
download software: midienc.zip |
