After a recent update the AVR Toolchain did nor longer work. It turned out that some links are missing. You can repair that easily. Login as root and then goto:
cd /opt/cross/avr
Now set the limks:
ln -s /usr/avr/sys-root/include include
ln -s /usr/avr/sys-root/lib lib
ln -s /usr/avr/sys-root/man man
ln -s /usr/avr/sys-root/share share
The toolchain should work again.
Clock Divider 2-8 front view
This clock divider divides the incoming clock signal down to /2, /3, …. /8. The output is a 5V positive pulse. The length of the incoming pulse is kept. The trigger is on the rising edge of the incoming signal. The reset input can be used for syncing with other clocks. All outputs are buffered and brought out parallel with LED signaling the pulse.
The documentation for download can be found in my website.
Clock Divider 2-8 schematic
Most work is done by the microprocessor. The micro takes care of the input and output timing. All outputs are independently buffered. The clock is made visible with LED.
Clock Divider 2-8 back view
BPM Generator module back
The BPM Generator give you +5V pulses output with 20ms length, from 40 to 240 beats per minute. Controlled by a microprocessor. The BPM are displayed with three 7 segment LED. The speed is adjusted with an rotary encoder.
The documentation for download can be found in my website.
BPM Generator module schematic main
Most work is done by the microprocessor. The micro takes care of the output timing and the multiplexing off the display. All four outputs are independently buffered.
BPM Generator module schematic display
BPM Generator module front
This is the last post about the mechanics. I promise. I have now a mechanical working keyboard with Kimber Allen contacts and the basic wiring. Next step are the electronics. I have them working since 2004 but it might be useful to do some rework with newer parts. I have to move from stripboard to PCB as well.
New holder waiting for contacts
Fitting the contacts and do some rework if needed.
Fitting the Kimber Allen contacts
Fitted and mounted with PCB
Fitted and mounted with PCB
Soldered and screwed
Contacts soldered and screwed
Putting it together
Contacts mounted with keyboard action
Some wires
First wiring to the shift register
Old scanner electronics from 2004
Old scanner electronic
And my first “keyboard” from 2004
First test keyboard
The new keyboard mechanic is working quite well with the old electronic. It is a lot of fun playing chords with the synthesizer. Next step is to think about the electronic. I want to get rid of the old stripboards and make some small PCB. Back then i used a ATmega8 and shift registers for keyboard scanning and a 16bit R2R ladder for DA conversion. Programmed in assembler. Maybe it is time to redo it in C and using a DA chip. I’ll give it a try.
Building a ADSR or LFO with certain features can become very complex and costly. And there are features that can not be realized at all. Like special waveforms. Other functions are hard to realize in the analog domain. So i wanted to experiment with a microprocessor in the digital domain. To start with i build a testboard around the ATMega328p and the 12bit analog to digital converter MCP4921. I added some hardware features that i found might be useful.
ATMega328p Testboard with MCP 4921
Analog inputs: 4Pots 2CV
CV inputs with selectable threshold +2.5V/+5V
Several digital inputs for switches.
Two digital inputs normalized to 5V with overvoltage protection
Analog output with 12bit DAC MCP4921</li>
Analog output switchable 0..5V / 0..10V / -5V..+5V
2 LED for visualizing analog output
External clock 20MHz
External voltage reference
ISP
ATMega328p Testboard with MCP4921 PCB