Thanks for this answer, which I think is incorrect for my version of the RPi (B+) but it helped me to find the correct answer.
Free GPIO pins are connected to the Expansion Header on the Audio Card. The Expansion Header is the header next to the SPKOUT connections. Pin 1 is the pin right next to SPKOUT R+.
The available GPIO pins are as follows:
Exp pin RPi pin GPIO
1 2 5V
2 - 3.3V
7 6 GND
8 6 GND
13 6 GND
14 29 5
16 22 25
17 31 6
18 32 12
19 36 16
20 37 26
There is (now after 2 years) another question to that point.
In addition to Wolfson CLAC on my RPi 2 B Model, i want to have a 2*16 LCD beeing fed via 4bit mode.
In total, this requires all of the six free pins left on Extension Pin Header. (mentioned above, GPIO 5,25,6,12,16,26).
That means: no GPIO left! But in the same time there i need another three GPIO PINs to be used for user interaction.
I already regret having decided for CLAC because of this design aspect that i was not aware of in advance.
But I looked in the manual
and found another free PINs "unused" (GPIO 4,27,24) (on page 15 of 21). Those are not available on the expansion header.
What is your guess, may it be possible to use them e.g. by contacting via a (not yet designed) break-out PCB?
Thanks for your contribution!
Assuming you are correct about the free pins, have you seen https://www.piborg.org/triborg?
It may do what you want. BTW, I am not compensated or have this, so lets us know what you think if you try it.
that Piborg PCB is exactly the kind of board that i was thinking of! Thanks for that hint.
Going through the CLAC documentation, I found that the mentioned RPi-GPIOs (BCM 4,24,27) are actually routed from the 40Pin header to input PINs of the sound processors on board of CLAC. But, "unused".
Anyway, the following warning is provided on p. 16 of the CLAC "user documentation"
Unused functions need to be treated carefully. Although they are not enabled in the current driver they provide scope for increased functionality going forward.
So, using them might cause trouble with future driver roll outs.
(on the other hand, will there reallly be so many driver updates in regard of the fact that they have stopped selling the card?)
As I already faced a lot of struggling with this card, I will check and let you know about my experience.
(it will maybe take some time until i have checked.)
Hi Gero, Hi Clem,
An other way to intercept unused GPIO signals between Pi and CLAC can be done with these kind of boards:
and then replace the 40 pin header with one with long pins like:
Then you can stack all on top of each other without modifying your Pi or CLAC
I use it myself to add functionality to a pizero / phatdac combination, but soon I intend to add rotary controllers and relay boards to my clac sets too.
The mere 6 GPIO pins transposed to the expansion header will be used up quickly.
As Hias rewrote the driver after 2 yeas of nothing from Cirrus Logic, He might be able to confirm the unused pins are really unused the the current driver.