Sienda Milan Library Reference Design - Sienda Network Processor (NXP i.MX 8M Plus)

Introduction

The Sienda Network Processor (NXP i.MX 8M Plus) is a Milan network processor reference design. Running on an NXP IMX8MPEVK development board with a real-time linux kernel and the Sienda Milan Application, this reference design provides a solid base upon which OEM products can be built.

To demonstrate the platform, a network Digital Audio Continuity Tester (DACT) is implemented, offering Milan audio input and output streams, and 8 channels of audio continuity testing at 48kHz.

The reference design is Avnu Milan Certified: https://avnu.org/v2product/642/

Getting started

To run the reference design you will need:

an NXP IMX8MPEVK from NXP
the reference design SD card image from Sienda
a 32GB MicroSD card

Wire it up

Ensure that the evaluation board boot mode (SW4) is set to boot from the MicroSD card. (SW4 should be set to 0011)
Flash the SD card image onto the MicroSD card using Balena Etcher or similar
Insert the MicroSD card into the MicroSD card slot on the evaluation board (on the underside)
Connect an ethernet cable between the ENET1 interface and your AVB network
Connect the NXP supplied USB-C power supply to the POWER socket, and power on the board

After approximately 30 seconds you should see the Milan device appear on the network:

Digital Audio Continuity Tester (DACT)

This reference design implements a Digital Audio Continuity Tester. The Milan entity has one stream output and one stream input. The stream output sends a stream containing a test tone (a slow sawtooth) on all channels, and then analyses the signal received on the stream input channels to verify it is the same. If the stream input doesn’t contain the same test tone then error counters will be incremented, and can be viewed as ATDECC controls:

To enable or disable the error counting (or to reset the counters) use the ‘Run Error Check’ control (set it to 1 to enable, set it to 0 to disable and reset):

The error counters will increment for each sample which is received on the stream input that does not have the expected value:

The Digital Continuity Tester can be used to test the egress or ingress parts of an AVB/Milan device, by applying the generated signal to a digital input and monitoring the egressing stream, or by applying the test tone via the AVB stream and monitoring a digital output of the device. It can also be used to test a digital input/output of an AVB/Milan device by creating a loopback between a digital output to a digital input, and then applying the test tone through the AVB stream and monitoring the returned stream. The two parts of the DACT (the tone generator and the error detector) may be used separately, so that (for example) a Milan talker device in development may be programmed to generate the test tone, and the DACT used to verify signal integrity in the Milan egress path. The reverse may also be done to test the ingress stream path of a listener device in development.

The DACT test tone signal is a linear incrementing signed 32 bit integer value. This will thoroughly exercise a 32bit i2s/TDM interface. If compatibility with 24bit integer i2s/TDM/AES3 interfaces is required then a build of the DACT dll is available that ignores the lower 8 bits.

Contact us

If you are interested in developing a Milan product based on our Milan Linux Application (or any of our RTOS based designs), then please get in touch!

Kieran Tyrrell
www.sienda.com
sales@sienda.com