LimeNET-Micro Audio Output - Solved

#1

I have loaded the custom dt-blob.bin to successfully enable the 7 inch screen and RPi Camera on my LimeNET Micro, and now want to use the audio output from the 3.5 mm jack. It does not work by default and also seems to need changes to the dt-blob.bin.

Before I spend hours trying to get the right configuration, does anyone have exact details of how to get the audio working on a LimeNET Micro?

Thanks

Dave

1 Like
#2

An update, but no progress.

I see that the audio jack is fed from the CM3 GPIOs 40 and 41, so I have over-written the relevant entries in the CM3 device tree with:

			pin@p40 {
				function = "pwm";
				termination = "no_pulling";
				drive_strength_mA = <0x10>;
			};

			pin@p41 {
				function = "pwm";
				termination = "no_pulling";
				drive_strength_mA = <0x10>;
			};


			pin_define@PWML {
				type = "internal";
				number = <0x29>;
			};

			pin_define@PWMR {
				type = "internal";
				number = <0x28>;
			};

and then recompiled the dt-blob.bin and rebooted. However, still no audio.

Grateful for any further ideas.

Dave

#3

Hi,
If I remember correctly, it used to be enough to add:

dtparam=audio=on
dtoverlay=pwm-2chan,pin=40,func=4,pin2=41,func2=4

to /boot/config.txt

#4

@IgnasJ

Thanks very much - I have just entered that and it works. The changes to dt-blob.bin were not required.

@andrewback - please could this be documented somewhere on the Wiki?

Dave