@miero would have to confirm. But depending on the reasons for the question, perhaps these links would help.
https://raspberrypi.stackexchange.c...irming-the-i2s-pins-on-raspberry-pi-3-model-b
Starting with page 119 of the following, its obvious what a great asset Miero has been!
https://datasheets.raspberrypi.com/bcm2835/bcm2835-peripherals.pdf
If you have the RPi-Hermes, you could check which pins are active while its playing via I2S vs. not.
info on command to scan RPi GPIO status:
https://raspberrypi.stackexchange.c...he-gpio-readall-command-compatible-with-rpi-4http://wiringpi.com/the-gpio-utility/
https://raspberrypi.stackexchange.c...he-gpio-readall-command-compatible-with-rpi-4http://wiringpi.com/the-gpio-utility/
@francolargo thanks for the response and links, I appreciate it! I don't currently have the Hermes-RPi board and looks like the gents at TPA are closed until early February. I'm trying to understand what input pins it is connected to on the RPi to see if it'll work for my use case. From my understanding (I've worked with the Hermes-BBB version), there should be a GPIO pin that's set low or high depending on the sampling frequency of the music which can then be used to trigger the selection the correct external clock (one of 44.1kHz family or one for 48kHz family) which in turn is then fed back into the RPi via another GPIO as the actual clock to be used in generating the I2S output. I think this is what they refer to as clock slave mode (CLKM=1) on page 120 of the BCM2835 manual. So I'm really looking for the pin used for clock select (CS = ?) and then clock input (MCLK = ?), assuming the remaining I2S pins are the same (BCK 12; LRCK 35; DATA Out 40).
Hi there !
CS is GPIO 27 (pin 13)
Clock division factor is set using GPIO 22 23 24 (pin 15 16 18)
Check N0 N1 N2 CS board here:
https://www.diyaudio.com/community/threads/hermes-rpi-isolator-module-how-to.369388/#post-6575141
There is no masterclock on the Pi, the hermesPi card is taking the masterclock from the Cronus and is dividing it by the factor set by the three gpios 22 23 24 to generate the bitclock.
Then the bitclock is sent to the Rpi (and the Cronus too) which creates LRCK and Data out.
So RPi i2s pins are standard except that Bitclock is set as input (Bitclock slaved mode on the Rpi)
I see that GPIO 25 (pin 22) is used too, for some sort of mute flag I presume.
And finaly, 3.3v and Ground is used too (don't know which pins)
I hope it helps
CS is GPIO 27 (pin 13)
Clock division factor is set using GPIO 22 23 24 (pin 15 16 18)
Check N0 N1 N2 CS board here:
https://www.diyaudio.com/community/threads/hermes-rpi-isolator-module-how-to.369388/#post-6575141
There is no masterclock on the Pi, the hermesPi card is taking the masterclock from the Cronus and is dividing it by the factor set by the three gpios 22 23 24 to generate the bitclock.
Then the bitclock is sent to the Rpi (and the Cronus too) which creates LRCK and Data out.
So RPi i2s pins are standard except that Bitclock is set as input (Bitclock slaved mode on the Rpi)
I see that GPIO 25 (pin 22) is used too, for some sort of mute flag I presume.
And finaly, 3.3v and Ground is used too (don't know which pins)
I hope it helps