29 inputs with a single analog board

[Synthex]

Hello,

Would it be possible to develop a firmware for 29 inputs using only 3 chips 4051 on a single board ?
3 * 8 inputs + 5 inputs directly on the Atmega32 = 29 inputs.

Thanks !
Synthex

[dmitri]

Yes, it would:)

[Synthex]

Yes, it would

I knew that you were the man of the situation !

Having already built the 22 inputs, i would like add 7 inputs by this way ...

[Lakedaemon]

First congrats Synthex (and thanks) !
29 mono inputs make it on par with the TD20 for the number of inputs (one mono input short actually...^_^).


Secondly...Now, I think that I can guess what the Analogous board does :

Each 4051 inputs 8 mono inputs and it outputs a multiplexed signal through pin X that is then sent to the digital board.

Pins A, B and C code a number from 0 to 7 (000 to 111 in binary) and keep in sync with the multiplexed signal of pin X
and helps the Digital board De-multiplex the signal (i.e. know to what input a sample corresponds)

As their pins A, B and C are connected, the various 4051 (and the multiplexing they do) are synced.

Now, If I'm not mistaken....that makes the digital board theoritically able to input 64 inputs (this would be overkill) if you buy 8 multiplexer 4051...
(and I guess lots of bat45 diods and 100 resistors).

That means too that adding inputs to the Analogue board should be easy (and parts won't be wasted).

Now my questions are :
1) can the Atmega32 handle that much inputs ? If there is a limit (due to its speed), what do you think the limit is ?

2) you said you were working on a 32 inputs version of the analogue board...
How do you plan to do that ? (I'm curious)
I can understand 15 inputs, 22 inputs, 29 inputs, 36 inputs....but 32 inputs ?

[dmitri]

First congrats Synthex (and thanks) !
29 mono inputs make it on par with the TD20 for the number of inputs (one mono input short actually...^_^).


Secondly...Now, I think that I can guess what the Analogous board does :

Each 4051 inputs 8 mono inputs and it outputs a multiplexed signal through pin X that is then sent to the digital board.

Pins A, B and C code a number from 0 to 7 (000 to 111 in binary) and keep in sync with the multiplexed signal of pin X
and helps the Digital board De-multiplex the signal (i.e. know to what input a sample corresponds)

As their pins A, B and C are connected, the various 4051 (and the multiplexing they do) are synced.

Now, If I'm not mistaken....that makes the digital board theoritically able to input 64 inputs (this would be overkill) if you buy 8 multiplexer 4051...
(and I guess lots of bat45 diods and 100 resistors).

Don't be carried away:)

That means too that adding inputs to the Analogue board should be easy (and parts won't be wasted).

Now my questions are :
1) can the Atmega32 handle that much inputs ? If there is a limit (due to its speed), what do you think the limit is ?

I can say with 32 inputs it's close to a limit, but it can be overclocked to 20MHz:) Besides I tested Atmega644(can be Atmega324) which does 20MHz natively. I overclocked it to 24MHz and during a short test it was running fine (Atmega32 fails at 24MHz)

2) you said you were working on a 32 inputs version of the analogue board...
How do you plan to do that ? (I'm curious)

It is in testing. Look at the News page under 31/10/2007 date

I can understand 15 inputs, 22 inputs, 29 inputs, 36 inputs....but 32 inputs ?

It's just a side effect of a binary system:)

[Synthex]

I can say with 32 inputs it's close to a limit, but it can be overclocked to 20MHz:) Besides I tested Atmega644(can be Atmega324) which does 20MHz natively. I overclocked it to 24MHz and during a short test it was running fine (Atmega32 fails at 24MHz)

The quartz used for the 20MHz firmware version must be to 20MHz ?

Is it possible to use a PLL functionality to overclock the Atmega32 to 20 MHz with a quartz at 16MHz ?

This would make tests without having to change the quartz.

[dmitri]

I can say with 32 inputs it's close to a limit, but it can be overclocked to 20MHz:) Besides I tested Atmega644(can be Atmega324) which does 20MHz natively. I overclocked it to 24MHz and during a short test it was running fine (Atmega32 fails at 24MHz)

The quartz used for the 20MHz firmware version must be to 20MHz ?

Yes, it must.

Is it possible to use a PLL functionality to overclock the Atmega32 to 20 MHz with a quartz at 16MHz ?

This would make tests without having to change the quartz.

There is no such thing as PLL on Atmegas, at least not on Atmega8-128.