GPIO pins used by the Octo

Moderator: flatmax

flatmax
Posts: 609
Joined: Sat Jul 23, 2016 11:39 pm

GPIO pins used by the Octo

Post by flatmax » Thu Apr 27, 2017 10:01 am

This post lists the pins used by the Audio Injector Octo Sound Card for the Raspberry Pi.

For I2S :
pin 12 : Bit clock (GPIO18)
pin 35: LR clock (GPIO19)
pin 38: Data in (GPIO20)
pint 40: Data out (GPIO21)

For codec controls :
pins : 13, 15, 16, 18, 29
GPIOs : 27, 22, 23, 24, 5

The header pins are shown in this image :
viewtopic.php?f=5&t=4
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tha-poke
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Joined: Tue May 02, 2017 8:38 pm

Re: GPIO pins used by the Octo

Post by tha-poke » Tue May 02, 2017 8:49 pm

Hey

I have a project using another DAC simultaneously on the spi0 bus - on pins 19 , 21 , 23 and 24. Is it possible to reassign the GPIOs for the codec controls to not use pins 23 and 24?

Thanks for your help

Jamie

flatmax
Posts: 609
Joined: Sat Jul 23, 2016 11:39 pm

Re: GPIO pins used by the Octo

Post by flatmax » Tue May 02, 2017 11:28 pm

That would be a little difficult to accomplish. Can you please tell me how the DAC is using these pins ?

thanks
Matt
Check out our audiophile quality crossovers : https://bit.ly/2kb1nzZ
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tha-poke
Posts: 9
Joined: Tue May 02, 2017 8:38 pm

Re: GPIO pins used by the Octo

Post by tha-poke » Tue May 02, 2017 11:36 pm

The max11300DAC is connected to pins 19 MOSI 21 MISO 23 SCLK and 24 CE0. I have a driver working using wiringPi for spi.

What are the codec controls doing with GPIO 23 and 24?

tha-poke
Posts: 9
Joined: Tue May 02, 2017 8:38 pm

Re: GPIO pins used by the Octo

Post by tha-poke » Tue May 02, 2017 11:39 pm

I have spi working again now, I had to re-enable spi using raspi-config when the octo shield was attached. I still have no communication with the spi DAC when the octo is attached.

Thanks

flatmax
Posts: 609
Joined: Sat Jul 23, 2016 11:39 pm

Re: GPIO pins used by the Octo

Post by flatmax » Tue May 02, 2017 11:45 pm

OK - I think you may be ok, The Pi's SPI pins are available.

If I am not mistaken (as you mention) SPI pins are the following :
pins : 19, 21, 23, 24, 26

The octo only uses the following pins :
pins 12, 35, 38, 40
pins : 13, 15, 16, 18, 29


These are the equivalent GPIO ports :
GPIO: 18, 19, 20, 21
GPIOs : 27, 22, 23, 24, 5
Check out our audiophile quality crossovers : https://bit.ly/2kb1nzZ
Please review the Zero sound card on Amazon USA : https://www.amazon.com/dp/B075V1VNDD
---
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flatmax
Posts: 609
Joined: Sat Jul 23, 2016 11:39 pm

Re: GPIO pins used by the Octo

Post by flatmax » Tue May 02, 2017 11:47 pm

tha-poke wrote:I have spi working again now, I had to re-enable spi using raspi-config when the octo shield was attached. I still have no communication with the spi DAC when the octo is attached.

Thanks
OK - that is a good start. Can you probe the signals on the SPI lines and check they look like they should ?

Whilst the SPI pins are connected to the Octo's FPGA, they aren't in use.

thanks
Matt
Check out our audiophile quality crossovers : https://bit.ly/2kb1nzZ
Please review the Zero sound card on Amazon USA : https://www.amazon.com/dp/B075V1VNDD
---
Check out our new forum on github : https://github.com/Audio-Injector

tha-poke
Posts: 9
Joined: Tue May 02, 2017 8:38 pm

Re: GPIO pins used by the Octo

Post by tha-poke » Wed May 03, 2017 2:25 am

Everything seems fine on the spi lines , but wiringPi returns a different spi file descriptor when the octo is connected. Strange, any ideas let me know.

I have tried using the other chip enable line CE1 but the behaviour was the same.

Thanks

tha-poke
Posts: 9
Joined: Tue May 02, 2017 8:38 pm

Re: GPIO pins used by the Octo

Post by tha-poke » Wed May 03, 2017 8:06 am

Hi

There is definitely something going on with the spi pins.

I now have the octo working and the MAX11300 spi dac, the only way I could get the two to work together was to use jumpers cables instead of the header connection.

I connected the spi0 pins and pin 39 GND to the MAX11300 and all other pins to the Octo Injector with jumpers and all my code now works.

Could this be due to the spi connections to the fgpa on the octo? I was getting a response over spi but I'm not sure if it was from the MAX11300

Glad its all working though, I can live with using the jumpers for this project.

flatmax
Posts: 609
Joined: Sat Jul 23, 2016 11:39 pm

Re: GPIO pins used by the Octo

Post by flatmax » Thu May 04, 2017 12:50 am

Hmmm ... not sure.

SPI SS, which is pin 24 is pulled high by a 10k Ohm resistor (R10). That shouldn't effect your SPI system however.

One thing to do (if you are game) is to cut the tracks on the Octo PCB ... if you do this, try to cut towards the GPIO header side of the tracks and make sure it is the GPIO header side of R10. You would need to cut the tracks going to pins 19 and 21 on the top layer and pins 24 and 23 on the bottom layer.

What do you think ?
Matt
Check out our audiophile quality crossovers : https://bit.ly/2kb1nzZ
Please review the Zero sound card on Amazon USA : https://www.amazon.com/dp/B075V1VNDD
---
Check out our new forum on github : https://github.com/Audio-Injector

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