mardi 25 octobre 2011

new Schematics / Edit : Last update 1st nov.

The new schematics, with the midi input and output for the shield
The PCB has been sent to production, i should get them in 10 to 15 days.. 
the PCB will be based on this schematics:

1/12/11 : Schematics Removed, will add them again with the corrected one..
Feb 12 : Last Schmatics are on googlecode.

PCB should look like this..:

And finally the Eagle 3d Preview  (wihout midi connectors) :

mercredi 19 octobre 2011

autoshutown 2 the return

Finally i got the reset of autoshutdown working .. (need to verify but don't know how to do a midi note every 20 sec without doing it manually).

When pressing the "erase button" it connect the pin 6 to the pin 33 in the microctronller (via the membrane keypad), the pulse shown in the previous post will output from pin 33 and goes in the pin 6.

After few tests the conclusion is :  needed to recrate this pulse and it need to be well synced with the signal from pin 6. Using port maipulation i get env, 500 ns difference between the received pulse and the created one.
Normally this pulse should simulate a "erase" keypress and erase the screen if you press a letter button before.i execute the function (generate the pulse after every midi note) and strangely it does not erase the screen each time .. but seems to reset the autoshutdown counter correctly. To be sure it will erase the screen i should do a few of theses pulses, be they appear each 7,x ms , so if i want to put 4 pulse it will take approx 30 ms, after each midi note, which is far too much i think if you want to trigger the note quickly (not sure the S&S will accept not ever 20 ms need to be tested). i prefer to keep responsiveness of the S&S.

I also tried something totally different, remove the negative voltage from the interface and replace it with the GND, it should work in theory because the bus should have pulldown resistor.
Result  : it works , yeah .. but with some interference on the VFD display.

With the negative voltage
 correct screen with the underscore (the ctl8 pulse is due to this underscore)


Without negative voltage  you get strange display but works.

I'm tired of all this cable and stuff
 that's why i'm designing a sort of shield (smaller one)for arduino, once done, will sent it to a PCB prototyping service.
This shield will be usable to the arduino to S&S interface, will power the arduino with S&S batteries, it could also be used as a midi shield.

mercredi 5 octobre 2011


The Speak and spell got a anoying feature, the autoshutdown when no button is pressed.
By using the arduino Speak and Spell interface, we inject signals directly into the speech synth and not using any button. So the Speak and Spell will power off after few minutes.
We will need to add a "automatic button press" when a midi note is played to ensure the device does not power off. For example the "/" or "erase" on the keyboard don't do any sound ..  sounds the good key to use ..

First find the connection on beetween the CPU and the keyboard :
 Keyboard connector pin   ->  CPU pin
1   ->  2
2   ->  6             used for the "/" or erase key
3   ->  5
4   ->  33           used for the "/"or erase key 
5   ->  32
6   ->  Vbatt+
7   ->  31
8   ->  30
9   ->  34
10   ->  29
11   ->  28
12   ->  4
13   ->  3

Next step watch the signals ... on the Cpu pin 6 = nothing interesting.
on pin 33 .. a pulse of approx. 500 uS.

So will check if generating a pulse will do the job of if the pulse need to be correclty timed and triggered..