NXP Semiconductors Harpoon User manual

Harpoon User's Guide
NXP Semiconductors Document identifier: HRPNUG
User Guide Rev. EAR 2.1.0, 30 June 2022

Contents
Chapter 1 Overview............................................................................................... 3
1.1 Architecture............................................................................................................................... 3
1.2 Hardware resource partitioning................................................................................................. 4
Chapter 2 Building Harpoon Yocto images............................................................6
2.1 i.MX Yocto................................................................................................................................. 6
2.2 Real-time Edge Yocto................................................................................................................6
Chapter 3 Hardware Setup.................................................................................... 7
3.1 i.MX Reference Boards............................................................................................................. 7
3.2 Audio use case hardware..........................................................................................................9
3.3 Industrial use case hardware...................................................................................................12
Chapter 4 Running Harpoon Reference Applications.......................................... 14
4.1 Basic setup..............................................................................................................................14
4.2 Starting Linux kernel................................................................................................................14
4.3 Audio application..................................................................................................................... 15
4.4 Industrial application................................................................................................................19
4.5 rt_latency application...............................................................................................................31
Chapter 5 Known Issues......................................................................................35
Chapter 6 Technical Details on Harpoon Applications.........................................36
6.1 Description...............................................................................................................................36
6.2 Manual build............................................................................................................................ 36
6.3 Starting an RTOS application with Jailhouse.......................................................................... 38
6.4 Developing a Harpoon Application.......................................................................................... 38
Chapter 7 Revision History.................................................................................. 42
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Chapter 1
Overview
This document presents the Harpoon release (EAR) 2.1 for i.MX 8M device family, using the Arm Cortex-A53 processor
(Armv8-A architecture).
Harpoon provides an environment for developing real-time demanding applications on an RTOS running on one (or several)
Cortex-A core(s) in parallel of a Linux distribution, leveraging the 64-bit Arm architecture for higher performance.
The system starts on Linux and the Jailhouse hypervisor partitions the hardware to run both Linux and the guest RTOS in parallel.
The hardware partitioning is configurable and depends on the use case. This release includes an audio application, an industrial
application and a real-time latency measurement application, all available both for FreeRTOS as well as Zephyr (some application
feature limitations exist depending on the selected platform and RTOS).
This release supports the following software and hardware:
• NXP Linux Yocto
— i.MX LF 5.15.32_2.0.0: For more information, see i.MX Yocto Project User's Guide.
— Real-time Edge Rev. 2.3: For more information, see Real-time Edge Yocto Project User Guide.
• i.MX 8M Series
—i.MX 8M Mini LPDDR4 EVKB
—i.MX 8M Nano LPDDR4 EVK
—i.MX 8M Plus LPDDR4 EVK
• Jailhouse hypervisor
• FreeRTOS V10.4.3 kernel
— Cortex-A53 port, uniprocessor
— Guest OS running on Jailhouse cell
• Zephyr RTOS 3.0.0
— Cortex-A53 port, SMP
— Guest OS running on Jailhouse cell
• MCUXpresso SDK 2.11
— GIC, Timer and MMU Cortex-A53 drivers
— CAN, ENET, ENET_QOS, GPT, I2C, SAI, and UART SoC drivers
— Audio Codec drivers
— Phy drivers
• RTOS Applications
— Audio reference application
— Industrial reference application
— Real-time latency measurement application
1.1 Architecture
The following figure shows the architecture of the Harpoon solution.
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Figure 1. Harpoon solution architecture
The i.MX 8M box shows the hardware partitioning between Jailhouse cells.
The boxes in dark orange (group 1) show the main hardware blocks allocated to the Linux OS.
The boxes in blue (group 3) show the main hardware blocks allocated to the RTOS.
The boxes in light orange (group 2) show the main hardware blocks shared between Linux and the RTOS.
Harpoon-apps is the real-time application running on Jailhouse's inmate cell. It is built on top of the FreeRTOS and
MCUXpresso drivers.
1.2 Hardware resource partitioning
Jailhouse hypervisor is used to run an RTOS in parallel with Linux: FreeRTOS and Zephyr are supported in this release.
Jailhouse is a simple hypervisor that assigns hardware resources to a guest OS instead of virtualising them. For instance, a CPU
core is statically assigned to a specific guest and is not shared with other guests.
In Jailhouse terms, the RTOS (inmate) runs in a cell. A configuration file describes which hardware resources are assigned to this
cell. This configuration file contains descriptions of the following:
• CPU cores assigned to the cell
• Interrupt lines assigned to the cell
• Memory regions assigned to the cell
• Virtual PCI devices used for communication between cells
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There is also a root cell configuration that describes the hardware prior to the hardware partitioning.
The source files of the cell configurations are embedded through patches in the Jailhouse recipe of the Harpoon meta-layer, at
the following locations:
•configs/arm64/imx8m*-freertos.c for the FreeRTOS rt_latency use case’s cell configuration
•configs/arm64/imx8m*-zephyr.c for the Zephyr rt_latency use case’s cell configuration
•configs/arm64/imx8m*-freertos-audio.c for the FreeRTOS audio use case’s cell configuration
•configs/arm64/imx8m*-zephyr-audio.c for the Zephyr audio use case’s cell configuration
•configs/arm64/imx8m*-freertos-industrial.c for the FreeRTOS industrial use case’s cell configuration
•configs/arm64/imx8m*-zephyr-industrial.c for the Zephyr industrial use case’s cell configuration
•configs/arm64/imx8m*.c for the root cell configuration
The CPU core allocated to the RTOS forms a bitmap in the cpu structure. Here, CPU core 3 is assigned to the cell:
.cpus = {
0b1000,
},
For a multicore (SMP) cell, two cores can be used, for instance:
.cpus = {
0b1100,
},
Memory regions assigned to the inmate cell are listed in the mem_regions structure. Memory regions can be reserved for the
inmate cell or shared with the Linux root cell.
Memory regions can be DDR chunks for the inmate cell use as well as device memory mapped regions such as UART or SAI.
Interrupts are mapped to the cell with the irqchips structure.
Virtual PCI devices are defined with the pci_devices structure. These virtual devices are used by Jailhouse to implement
IVSHMEM v2 communication channels.
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Chapter 2
Building Harpoon Yocto images
As mentioned in the overview section, Harpoon is compatible with both i.MX Yocto and Real-time Edge Yocto. Each distribution
is addressed in a separate section below.
2.1 i.MX Yocto
To build this release, fetch its Yocto manifest and get the meta-layers:
$ mkdir yocto
$ cd yocto
$ repo init -u https://source.codeaurora.org/external/imx/imx-manifest -b imx-linux-hardknott -m
imx-5.15.35-2.0.0_harpoon-v2.xml
$ repo sync
Then, prepare the environment with the following command:
$ DISTRO=fsl-imx-xwayland MACHINE=<machine> source imx-harpoon-setup-release.sh -b build.<machine>
Where, <machine> is one of the following:
•imx8mm-lpddr4-evk for i.MX 8M Mini EVKB board
•imx8mn-lpddr4-evk for i.MX 8M Nano EVKB board
•imx8mp-lpddr4-evk for i.MX 8M Plus EVK board
The end user license agreement must be accepted to continue.
Then build the image with the following command:
$ bitbake imx-image-core
The image is then available in subdirectory tmp/deploy/images/<machine>/.
Copy the disk image to a micro-SD card. For example, assuming the card is recognized as /dev/mmcblk0 by your host machine:
$ bzip2 -d -c imx-image-core-<machine>.wic.bz2 | sudo dd of=/dev/mmcblk0 bs=1M
The micro-SD card now contains the release.
2.2 Real-time Edge Yocto
Please refer to the Real-time Edge Yocto Project User Guide to build Harpoon and prepare an SD card for supported boards.
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Chapter 3
Hardware Setup
3.1 i.MX Reference Boards
This Harpoon release supports the following development boards:
[1]
Figure 2. i.MX 8M Mini EVK
[1] https://www.nxp.com/design/development-boards/i-mx-evaluation-and-development-boards/evaluation-kit-for-the-i
mx-8m-mini-applications-processor:8MMINILPD4-EVK
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[2]
Figure 3. i.MX 8M Nano EVK
[3]
Figure 4. i.MX 8M Plus EVK
[2] https://www.nxp.com/design/development-boards/i-mx-evaluation-and-development-boards/evaluation-kit-for-the-i
mx-8m-nano-applications-processor:8MNANOD4-EVK
[3] https://www.nxp.com/design/development-boards/i-mx-evaluation-and-development-boards/i-mx-8m-plus-evaluation
kit-enabling-power-measurement:8MPLUSLPD4-PEVK
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3.2 Audio use case hardware
Harpoon's audio application uses the I2S HiFiBerry audio card DAC+ ADC Pro :
[4]
Figure 5. HiFiBerry DAC+ ADC Pro (picture from HiFiBerry's website)
The HiFiBerry DAC+ ADC Pro is an audio card designed for the Raspberry Pi, but it can be connected to EVK boards using the
40-pin connector, provided a few adaptations are made.
The following pins on the EVK's 40-pin connector must be connected to the following HiFiBerry's pins:
Table 1. EVK - HiFiBerry transposition
EVK HiFiBerry Function
2 2 5V
3 3 I2C SDA
5 5 I2C SCK
6 6 GND
35 40 I2S TX
36 12 I2S clock
37 35 I2S word select for RX and TX
38 38 I2S RX
[4] https://www.hifiberry.com/shop/boards/hifiberry-dac-adc-pro/
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Figure 6. Handmade transposer
A complete setup, with a handmade transposer to respect above pinout, is shown as follows.
Figure 7. i.MX 8M Mini EVK with HiFiBerry audio card
The audio card has both an ADC (PCM1863) to record audio and a DAC (PCM5122) for audio playback.
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Record is done through the audio jack (connector highlighted in 1 in the following figure) and playback is done through the RCA
connectors (highlighted in 2).
[5]
Figure 8. HiFiBerry audio connectors (picture from HiFiBerry's website)
Control of the PCM1863 is done through I2C3, at address 0x4a.
Control of the PCM5122 is done through I2C3, at address 0x4d.
Both the PCM1863 and PCM5122 use i.MX I2S5. The I2S5 is the I2S clock master. Two oscillators (one for sampling frequencies
multiple of 44,100 Hz, one for sampling frequencies multiple of 48,000 Hz) are present on the HiFiBerry card, and controlled by
PCM5122 GPIOs.
The following diagram shows the HiFiBerry architecture:
Figure 9. HiFiBerry architecture
[5] https://www.hifiberry.com/shop/boards/hifiberry-dac-adc-pro/
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The PCM1863 and the PCM5122 use the same signal for I2S word select by using SAI synchronous mode.
3.3 Industrial use case hardware
Harpoon's industrial application may use the following hardware depending on the use case.
[6]
Figure 10. LS1028A AVB/TSN network bridge
The LS1028A RDB is used as a TSN bridge/switch in a TSN network to demonstrate the TSN ethernet use case running from the
inmate cell.
[6] https://www.nxp.com/design/qoriq-developer-resources/layerscape-ls1028a-reference-design-board:LS1028ARDB
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[7]
Figure 11. RT1170 TSN endpoint
The RT1170 is used as a TSN endpoint in a TSN network, exchanging packets with the i.MX 8MP board.
[7] https://www.nxp.com/design/development-boards/i-mx-evaluation-and-development-boards/i-mx-rt1170-evaluation
kit:MIMXRT1170-EVK
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Chapter 4
Running Harpoon Reference Applications
4.1 Basic setup
The EVK boards expose serial ports through their USB debug interface. One of these serial ports is used by Linux for its console,
and another one is used by the guest RTOS.
To run the reference applications, open both serial ports with terminal emulators, insert the micro-SD card on which the Yocto
image has been flashed in the EVK and power up the board.
4.2 Starting Linux kernel
Linux kernel must be started with a (Harpoon specific) Jailhouse compatible device tree.
To do this, when U-Boot is executing, stop at U-Boot prompt with a terminal emulator connected to the serial port and execute the
following command (based on the board and the application):
• For i.MX 8M Mini (audio or rt_latency):
u-boot => setenv jh_root_dtb imx8mm-evk-harpoon.dtb
u-boot => run jh_mmcboot
• For i.MX 8M Mini (industrial or rt_latency):
u-boot => setenv jh_root_dtb imx8mm-evk-harpoon-industrial.dtb
u-boot => run jh_mmcboot
• For i.MX 8M Nano (audio or rt_latency):
u-boot => setenv jh_root_dtb imx8mn-evk-harpoon.dtb
u-boot => run jh_mmcboot
• For i.MX 8M Nano (industrial or rt_latency):
u-boot => setenv jh_root_dtb imx8mn-evk-harpoon-industrial.dtb
u-boot => run jh_mmcboot
• For i.MX 8M Plus (audio or rt_latency):
u-boot => setenv jh_root_dtb imx8mp-evk-harpoon.dtb
u-boot => run jh_mmcboot
• For i.MX 8M Plus (industrial or rt_latency):
u-boot => setenv jh_root_dtb imx8mp-evk-harpoon-industrial.dtb
u-boot => run jh_mmcboot
This configuration is not persistent after a reboot.
NOTE
To make changes permanent, execute the following commands once (after setenv above):
u-boot => setenv bootcmd 'run jh_mmcboot'
u-boot => saveenv
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Now, at each reboot, the system starts with the Jailhouse compatible configuration and no user interaction is required.
4.3 Audio application
4.3.1 Features of the audio application
The audio application is available in the harpoon share directory of the target's root file system:
/usr/share/harpoon/inmates/freertos/audio.bin # FreeRTOS binary
/usr/share/harpoon/inmates/zephyr/audio.bin # Zephyr binary
This application contains several running modes that can be started and stopped via a user space application running on Linux
called harpoon_ctrl.
The different modes are:
• DTMF playback: plays a DTMF sequence.
• Sine wave playback: plays a generated sine wave.
• Loopback: record sound from HiFiBerry's input and play it live through HiFiBerry's output.
• Full Audio pipeline: implements a flexible 3-stage pipeline with different sources (DTMF, sine waves, SAI input) that can be
routed to different sinks (SAI outputs).
All the modes support:
• Basic pipeline framework for audio processing
• 44100, 48000, 88200, 176400, 96000, and 192000 Hz sample frequency
• Audio processing period with 2, 4, 8, 16, or 32 frames
• Audio processing in 64bit float format
• Audio playback to both SAI3 (on board codec/sound jack) and SAI5 (HifiBerry)
• Audio capture from SAI5 (HifiBerry)
4.3.2 Starting the audio application with Jailhouse
The harpoon service uses the /etc/harpoon/harpoon.conf configuration file that contains the RTOS and the application to run.
By default, the configuration file points to the FreeRTOS audio application. To use the Zephyr audio application, the following
command can be run to generate an appropriate configuration file:
# harpoon_set_configuration.sh zephyr audio
To use the audio application, Jailhouse must be started first. To start Jailhouse and the audio application, run the harpoon service
with systemd:
# systemctl start harpoon
Once the harpoon service has been started, harpoon_ctrl is used to start or stop the audio modes with optional parameters. The
different options for the audio application are:
Audio options:
-f <frequency> audio clock frequency (in Hz)
Supporting 44100, 48000, 88200, 176400, 96000, 192000 Hz
Will use default frequency 48000Hz if not specified
-p <frames> audio processing period (in frames)
Supporting 2, 4, 8, 16, 32 frames
Will use default period 8 frames if not specified
-r <id> run audio mode id:
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0 - dtmf playback
1 - sine wave playback
2 - playback & recording (loopback)
3 - audio pipeline
-s stop running audio mode
Audio pipeline options:
-a <pipeline_id> audio pipeline id (default 0)
-d audio pipeline dump
Audio element options:
-a <pipeline_id> audio pipeline id (default 0)
-d audio element dump
-e <element_id> audio element id (default 0)
-t <element_type> audio element type (default 0):
0 - dtmf source
1 - routing
2 - sai sink
3 - sai source
4 - sine source
Routing audio element options:
-a <pipeline_id> audio pipeline id (default 0)
-c connect routing output
-d disconnect routing output
-e <element_id> routing element id (default 0)
-i <input_id> routing element input (default 0)
-o <output_id> routing element output (default 0)
4.3.3 Audio latency in loopback mode
The loopback mode reads audio samples from HiFiBerry's ADC in an audio buffer and sends this buffer to the HiFiBerry's DAC
when fully loaded.
The end to end latency, between the analog audio input and the analog audio output, has been measured and is dependent on
the audio buffer size and the audio sampling rate. The RTOS and SoC combination does not alter the latency measurements.
Table 2. Audio application latency
Sampling
rate (kHz)
Audio latency (μs)
Audio buffer size (frames)
32 16 8 4 2
192 610 440 360 320 300
176.4 660 480 390 340 330
96 1210 870 700 630 580
88.2 1310 940 770 680 630
48 2380 1720 1390 1220 1140
44.1 2600 1880 1510 1310 1240
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4.3.4 Running audio application: examples
4.3.4.1 Playing DTMF
To start DTMF playback with default parameters (48000 Hz sampling rate):
# harpoon_ctrl audio -r 0
The DTMF is played both to the Hifiberry RCA outputs as well as the onboard jack.
To run another audio use case, the playback must be stopped with the following command:
# harpoon_ctrl audio -s
4.3.4.2 Playing in loopback mode
In loopback mode, the SAI input is copied to the SAI output.
To start loopback mode with default parameters (48000 Hz sampling rate, 8 frame period size):
# harpoon_ctrl audio -r 2
To run another audio use case, the playback must be stopped with the following command:
# harpoon_ctrl audio -s
4.3.4.3 Playing a full audio pipeline
The reference audio application is based on a basic pipeline framework for audio processing. Different audio processing elements
can be assembled in a pipeline to process audio from source(s) to sink(s). The pipeline is processed in real time, cyclically with
a fixed period.
In the audio pipeline mode there is a three stage pipeline composed of a routing element in stage 2 which can link source elements
from stage 1 to sink elements from stage 3.
Audio pipeline with multiple sources/sinks and a routing element
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Figure 12. Audio pipeline
When running the audio pipeline, the routes can be configured dynamically with the harpoon_ctrl command. This command uses
source and sink indices to connect elements.
Table 3. Indices of source elements
Index Source element Comments
0 DTMF, sequence 1 Software generated source
1 DTMF, sequence 2 Software generated source
2 Sine wave, 440 Hz Software generated source
3 Sine wave, 880 Hz Software generated source
4 SAI5, left channel Hardware source
5 SAI5, right channel Hardware source
6 SAI3, left channel Hardware source
7 SAI3, right channel Hardware source
Table 4. Indices of sink elements
Index Sink element Comments
0 SAI5, left channel Hardware sink
Table continues on the next page...
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Table 4. Indices of sink elements (continued)
1 SAI5, right channel Hardware sink
2 SAI3, left channel Hardware sink
3 SAI3, right channel Hardware sink
This makes for a flexible pipeline. For instance, the following commands starts the pipeline and configures the routing element
to have a loopback between SAI5 input and SAI3 output (i.e. sound recorded by the HiFiBerry card played by the EVK's internal
codec) while a DTMF sequence is played on the left channel of SAI5's output and a 440 Hz sine wave on the right channel of SAI5's
output (i.e. HiFiBerry's output):
# harpoon_ctrl audio -r 3 # start audio pipeline
# harpoon_ctrl routing -i 4 -o 2 -c # SAI5's input to SAI3's output (L)
# harpoon_ctrl routing -i 5 -o 3 -c # SAI5's input to SAI3's output (R)
# harpoon_ctrl routing -i 0 -o 0 -c # DTMF to SAI5's output (L)
# harpoon_ctrl routing -i 2 -o 1 -c # sinewave 440Hz to SAI5's output (R)
4.4 Industrial application
4.4.1 Features of the industrial application
The industrial application is available in the harpoon share directory of the root file system:
/usr/share/harpoon/inmates/freertos/industrial.bin # FreeRTOS binary
/usr/share/harpoon/inmates/zephyr/industrial.bin # Zephyr binary
This application contains several use cases that can be started and stopped via the Harpoon Linux user space application,
namely harpoon_ctrl.
In the current release, a single industrial use case is supported under Zephyr: CAN on i.MX 8M Plus EVK.
NOTE
The different use cases are:
• CAN (i.MX 8M Plus EVK):
— Simple loopback example that uses the flexCAN interface to send and receive CAN messages through internal loopback
interconnect (no cable required).
— Ping-pong: Two boards are connected through their CAN1 connectors (J19) with a male-male DB9 CAN cable. The later
can either be purchased or built following the CAN pinout standard. Endpoint A (board A) sends CAN FD messages
to Endpoint B (board B). Endpoint B uses two receiving queues to receive messages in turns, and prints the message
content (and the receiving queue number) to the terminal after any queue is full.
• Ethernet (FreeRTOS only):
— Simple MCUXpresso SDK API based application to send and receive packets through the ENET interface (i.MX 8M
Mini/Nano EVK)
— Full TSN stack based application, running a gPTP stack and sending/receiving TSN packets on a TSN network:
◦ Through the ENET_QOS interface, acting as a controller/IO device (i.MX 8M Plus EVK).
◦ Through the ENET interface, acting as a controller/IO device (i.MX 8M Mini EVK).
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The ENET interface does not support 802.1Qbv. Packets are transmitted using basic, software based, strict
priority scheduling.
NOTE
4.4.2 Starting the industrial application
To use the industrial application, Jailhouse must be started first. To start Jailhouse and the industrial application, create the
corresponding Harpoon configuration file and run the harpoon service using systemd ; for instance:
# harpoon_set_configuration.sh freertos industrial
The configuration file is stored under /etc/harpoon/harpoon.conf and the harpoon systemd service uses it to start Jailhouse
and the industrial application:
# systemctl start harpoon
Once the harpoon service has been started, harpoon_ctrl is used to start or stop the industrial features with optional parameters.
The different options for the industrial application are:
Industrial CAN options:
-r <id> run CAN mode id:
0 - loopback
1 - interrupt
2 - pingpong
-n <node_type> acting as node 'A' or 'B' (default 'A')
0 - node 'A'
1 - node 'B'
-s stop CAN
Industrial ethernet options:
-a <mac_addr> set hardware MAC address (default 91:e0:f0:00:fe:70)
-r <id> run ethernet mode id:
0 - genAVB/TSN stack
1 - mcux-sdk API (imx8m{m,n} ENET)
-i <role> for genAVB/TSN: endpoint role (default 'controller', if not specified)
0 - role is 'IO device 0'
1 - role is 'IO device 1'
-s stop ethernet
4.4.3 Running the industrial application: examples
4.4.3.1 CAN use cases
Loopback
Type this command to start a CAN loopback transfer (CAN FD mode enabled by default):
# harpoon_ctrl can -r 0
To execute a new CAN use case, the previous run must be stopped with the following command:
# harpoon_ctrl can -s
Ping-pong
One board must be chosen as node A and the other board as node B. (Note: Node B should start first) Data is sent from the node
A to the node B.
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