Many thanks.

73

de Pat G4GVW
QTH Nr Felixstowe, Suffolk
East coast of UK

On 11/09/14 18:16, LZ wrote:

Hi,

Got the Wolfson card running. Very first impressions:

Since I don't want to compile a new kernel
(>12h on the R-Pi) I used that image:
http://blog.georgmill.de/wp-content/uploads/2014/04/kernelAndFirmware_wolfson_rt.tar.bz2

On a Linuxbox I unzipped it and wrote the image to a 4Gb
card using an ordinary cheap card reader:
dd if=2014-01-07-wheezy-raspbianW.img of=/dev/sdd
"of" is the device of the card reader got by "fdisk -l"
(Don't ask me about doing this on a WinBox. Poor girl here.)

Plugged into a R-Pi with the "Wolfson" in place this image
booted without any errors. It will run "raspi-config"
first where you have to do some boring config tasks
(lang. etc.). OT here.

Next I plugged in an antenna/preamp into the red plug
and started this modified bash script as root (!):

#!/bin/bash

# Record from onboard Line Input to AP

# input PGA gain
amixer -Dhw:0 cset name='IN3L Volume' 4 # (mod by Laura)
amixer -Dhw:0 cset name='IN3R Volume' 4 # (mod by Laura)

# better THD in normal mode vs lower noise floor in high performance
amixer -Dhw:0 cset name='IN3 High Performance Switch' on

amixer -Dhw:0 cset name='IN3L Digital Volume' 128
amixer -Dhw:0 cset name='IN3R Digital Volume' 128

amixer -Dhw:0 cset name='LHPF1 Input 1' IN3L
amixer -Dhw:0 cset name='LHPF2 Input 1' IN3R
amixer -Dhw:0 cset name='LHPF1 Mode' High-pass
amixer -Dhw:0 cset name='LHPF2 Mode' High-pass

amixer -Dhw:0 cset name='AIF1TX1 Input 1' LHPF1
amixer -Dhw:0 cset name='AIF1TX1 Input 1 Volume' 32
amixer -Dhw:0 cset name='AIF1TX2 Input 1' LHPF2
amixer -Dhw:0 cset name='AIF1TX2 Input 1 Volume' 32

# The following command should be used to test (mod by Laura)
arecord -Dhw:0 -r 192000 -c 2 -f S16_LE test.wav

Looking into "test.wav" with "Baudline" all the usual suspects
from 10-96 kc are present. The "Wolfson" appears quiet and flat.
At ~53 and ~63kc I'm observing some signals from the 2nd
Nyquist domain. The experts will know which.

Boring: running "arecord" I got many overruns. Overclocking
(900 Mhz) did not cure this. Guess it's due to a slow SD card.
Next step: streaming. Hope that "flac" will work. ?

Laura

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