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Signal routing is also useful for hardware debugging of microphone or reference signal connection.
As an example, the following command routes USB reference channel 0 from host to the USB audio
output channel 0 of XVF3510:
vfctrl_usb SET_IO_MAP 0 7
A loopback of reference signal input XVF3510 and its audio output is formed. By playing back signal,
e.g. a sine wave as the reference signal output from host, the user can verify if the signal is being
received properly by XVF3510 through its audio output. If the audio signal recorded at host is different
from the reference output, the user may check if the problem is caused by hardware connection failure
or wrong data format.
Signal routing can also be used for debugging microphone signal:
vfctrl_usb SET_IO_MAP 1 12
The above command routes microphone channel 1 as the direct signal to XVF3510's USB audio
output. Microphone signals can the be verified by recording XVF3510's audio output.
For XVF3510-UA, its I
2
S master interface can be used for sending out different kind of signal shown in
the source channel table while having USB outputs of processed audio. For example, the following
command configures to send channels of mic, reference and pipeline outputs in 16kHz sampling
frequency packed to 48kHz I
2
S output:
vfctrl_usb SET_IO_MAP 2 16
vfctrl_usb SET_IO_MAP 3 16
By using Raspberry Pi with I
2
S slave interface configured, the user can then capture synchronized
signals of mic, reference and pipeline output. Observing these signals can be very useful for
debugging. The packed signal can be unpacked to mic, reference and pipeline signal with 2 channels
in each of them by using a Python script provided in the Release Package.
The SET_OUTPUT_SHIFT command can be used to specify a bit shift that is applied to all samples
of a given target. For example, specifying:
vfctrl_usb SET_OUTPUT_SHIFT 2 4
applies a left shift of 4 bits on all samples output from the device on I2S channel 0 as 2
4
=16x of gain.
A negative shift value would imply a right bit shift for attenuation.
The GET_IO_MAP_AND_SHIFT command displays the IO mapping and the shift values for all targets.
Executing a GET_IO_MAP_AND_SHIFT command without having set any mapping or shifts explicitly
shows the default mapping that is configured in firmware.
vfctrl_usb GET_IO_MAP_AND_SHIFT
GET_IO_MAP_AND_SHIFT:
target: USB_FROM_DEVICE_0, source: PIPELINE_OUT_0 output shift: NONE
target: USB_FROM_DEVICE_1, source: PIPELINE_OUT_1 output shift: NONE
target: I2S_FROM_DEVICE_0, source: PIPELINE_OUT_0 output shift: NONE
target: I2S_FROM_DEVICE_1, source: FAR_END_IN_0 output shift: NONE
target: REF_TO_PIPELINE_0, source: USB_TO_DEVICE_0 output shift: NONE
target: REF_TO_PIPELINE_1, source: USB_TO_DEVICE_1 output shift: NONE
XM-014232-PC
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