Quick Start Guide for SOM-352 Family

1. Objective

The purpose of this document is to provide necessary information to help setup and installation of SOM-352 series products. To provide for safe installation and operation of the equipment, read the safety guidelines at the beginning of this manual and follow the procedures outlined in the following chapters before connecting power to SOM-352. Keep this operating manual handy and distribute to all users, technicians and maintenance personnel for reference.

2. Reference

• PCI Express Mini Card Electromechanical Specification 2.0/2.1
• I-PEX MHF Micro RF coax connector product series catalog
• I-PEX MHF I Connector Instruction Manual (HIM-10002-06EN)
• Unex SOM-352 datasheet
• SOM-352 drawing 51-00009-02
• Unex’s documentation (in Unex’s software release package)
• NEO-M9V Integration manual (UBX-21029776)

3. Limited Warranty Policy

Unex Technology Corporation selling the product warrants that commencing from the date of shipment to customer and continuing for a period of twelve (12) months. This limited warranty extends only to the original customer of the product. Customer’s sole and exclusive remedy and the entire liability of Unex under this limited warranty will be, at Unex’s option, return for repair to Unex’s repair center with freight and insurance prepaid or shipment of a replacement within the warranty period or a refund of the purchase price if the hardware is returned to Unex. Unex’s obligations hereunder are conditioned upon the return of affected hardware in accordance with Unex’s service center’s then-current Return Material Authorization (RMA) procedures.

This warranty does not cover:

• Products found to be defective after the warranty period has expired.
• Products subjected to misuse or abuse, whether by accident or other causes. Such product conditions will be determined by Unex at its sole and unfettered discretion.
• Products damaged due to a natural disaster, including but not limited to lightning, flooding, earthquake, or fire.
• Software products.
• Products dismantled or opened by unauthorized persons. Please contact a representative of Unex if you need advanced technical support.
• Products with an altered and/or damaged serial number.
• Loss of data or software.
• Products that have been updated, reworked, or improperly tested by the Customer, or by a third party at the request of the Customer.
• Customized and original design manufacturer (ODM) products. The warranty terms for customized and ODM products should be defined in the contract that governs the project.

4. Safety Guidelines

• Keep working area clean and dry while assembling/installing.
• When operating under extreme temperature conditions, environmental control measures (e.g., heating, cooling) should be considered.
• Make sure every accessory has been fastened, including the V2X antenna cables, GNSS antenna cable, and the mPCIe socket latch/screws.
• Follow the Attention instructions.

  Attention	Follow the operation instructions to make sure the product functioning properly and to avoid product damages during handling / installation / operation.

• Follow the Caution instructions.

  Caution	Follow the safety instructions to keep users / operators from health hazards.

5. Installation Instructions

5.1. IMU-mount Alignment

SOM-352 (0B) features an integrated onboard IMU (inertial measurement unit) for DR (dead reckoning) navigation. It is important to make sure the IMU orientation aligns with the vehicle chassis frame if mounted on a vehicle or a moving platform. Please refer to FIGURE 1: IMU ALIGNMENT for correct installation using default orientation settings.

If the mounting orientation cannot align with vehicle chassis frame because of physical constrains, please refer to NEO-M9V Integration manual (UBX-21029776), section 3.2.4.1 for more detailed instructions.

For stationary applications such as an RSU, IMU alignment is not necessary.

5.2. Installation Steps

Follow the instructions below to install the SOM-352 into a host system:

1. Shut down the host system and switch it off.
2. Disconnect the host system from its power supply.
3. Open the host system’s enclosure.
4. Insert the SOM-352 into an empty PCI Express slot. Following the host systems’ instruction to complete the mechanical fastening.
5. If a Molex Pico-Lock I/O cable is necessary for host system integration, connect it to the SOM-352. (see 9.3 I/O CABLE PINOUT)
6. Connect GNSS antenna cable to the SOM-352. (see 9.1 ANTENNA CONNECTORS, 9.1.1 V2X)
7. Connect V2X antenna cables to the SOM-352. (see 9.1 ANTENNA CONNECTORS, 9.1.2 GNSS)
8. Close the host system’s enclosure.
9. Reconnect the power supply of the host system.

6. Product Appearance

The photos in this document may differ from actual product; the Model and Part No. on label may differ for each model. However, the differences do not affect actual functionalities.

7. Functional Block Diagram

8. Electrical Characteristics

8.1. Absolute Maximum Ratings

Over operating free-air temperature range (unless otherwise noted).

8.2. Recommended Operating Conditions

Over operating free-air temperature range (unless otherwise noted).

8.3. Power Consumption

SOM-352 can be powered in two different ways: dual voltage (5V/3.3 Vaux) from mPCIe or 5V from external cable. The data listed in table 3 and table 4 serve only as a reference for system integrators. The actual conditions will vary depending on firmware version and user applications.

9. I/O Interfaces

9.1. Antenna Connectors

The SOM-352 mPCIe module is provided with three 50 Ω RF connectors (see FIGURE 4: ANTENNA CONNECTORS):

• two V2X antennas
• one GNSS antenna

Receptacle connectors are I-PEX MHF I 20279-001E-03. For more information about mating plug connectors, visit the website https://www.i-pex.com/product/mhf-I for details.

The antenna connection is one of the most important aspects in the full product design as it strongly affects the RF performance. Connecting cables between the module and the antenna must have 50 Ω impedance. If the impedance of the module is mismatched, RF performance will be reduced significantly.

Please be careful when extracting the antenna cables from a SOM-352 module. Extracting the connector by pulling the cable may cause damage on the antenna plug assembly. It is recommended to extract the cable using a proper extraction tool suggested by the cable plug manufacturer. For I-PEX plugs please use I-PEX 90192-001 or 90224-001.

9.1.1. V2X Antenna Detection

The V2X antenna ports has a built-in antenna detection function (see TABLE 5). This detection mechanism only works with Unex V2X antennas EX-55 or EX-53.

Please note that the EX-55/EX-53 antennas are not included in SOM-352 product package and can be purchased separately.

9.1.2. GNSS

For stable fix acquisition, at least 4 satellites with enough signal strength (C/N₀ value above 30 dB-Hz) are required. If the signal strength goes below 30 dB-Hz, the fix will become unstable.

9.1.2.1. GNSS Antenna Detection

The antenna detection mechanism is a 2-step process: First check the signal strength. If the signal strength drops to zero, then check the antenna status flag.

When all the C/N₀ values becomes null, it means that the GNSS antenna or its cable may either become detached or damaged. The GNSS antenna port has a built-in antenna detection function. The detection mechanism is based on the current consumption of an active antenna (I_ANT). If the active antenna consumes less current than 8 mA, then it is considered as the OPEN status; if the antenna consumes more than 64 mA, then it is considered as the SHORT status. Anything between 8-64 mA is considered as the NORMAL status. In Unex SDK 1.13.10 or later, the OPEN/SHORT thresholds are saved in a config file /etc/unex/conf/bx_antenna_status.conf, and can be modified according to the specific antenna of choice.

Unex’s proprietary gpsd software will monitor the antenna current (I_ANT) constantly. The GNSS 3.3V antenna bias (V_ANT) will be continuously supplied in OPEN/NORMAL status. However, once the SHORT status is triggered, the SHORT flag will persist, and the 3.3V bias will be turned off until the reset of the GNSS module. After the reset of the GNSS module, the detection process will start all over again. Turning off the V_ANT is done by sending the commands listed in TABLE 7: GNSS 3.3V ANTENNA BIAS (V_ANT) STATUS to the u-blox NEO M9V module.

If Unex’s gpsd software is not used, then the monitoring of the I_ANT and control of 3.3V antenna bias should be implemented by user.

It is possible for a good active antenna to be reported OPEN because it consumes less current than 8 mA, or a good passive antenna to be considered SHORT because it is DC shorted (e.g., a slot antenna). However, as long as more than 4 satellites with enough signal strength (C/N₀ value above 30 dB-Hz) present in sky view, the GNSS is considered in good state.

9.2. Mini PCIe Card Pinout

There are 3 groups of pins in the SOM-352 mPCIe pinout:

• Group 1: Proprietary pins, originally marked as reserved in mPCIe standard interface
• Group 2: Standard mPCIe pins used by SOM-352, including 3.3 Vaux, ground, PERST#, and USB data lines
• Group 3: Standard mPCIe pins but not used in SOM-352, marked NC

SOM-352 only needs group1 and group2 pins for normal operation. For maximize compatibility with existing mPCIe modules on the market, it is suggested to connect all three groups of pins to the mPCIe connector.

Please note that the I/O directions listed here are on the SOM-352 side. For designing a system board mPCIe interface, the input and output direction must be reversed.

9.3. I/O Cable Pinout

The I/O cable can help user to install SOM-352 on an existing mPCIe system board without modifying the system board hardware. Make sure to set the SW1.1 configuration accordingly before the I/O cable is connected. Please see 9.4 DIP SWITCH and TABLE 11: DIP SWITCH FUNCTIONS for detailed instructions.

Please note that the pinout listed here is seen from the SOM-352 side. For designing an I/O cable interface on the system board, the input and output direction must be reversed.

The 7-pin cable connector is Molex Pico-Lock system 504051-0 01 and the contact is 504052-00 8.

9.4. DIP Switch

The onboard DIP switch can help user to direct power and I/O signals from either mPCIe interface or the I/O cable. The tamper signal trigger mode and firmware upgrade can also be selected by user.

Please note that the in SW1.1 to SW1.6, the OFF position actually disconnects the power/signal from the mPCIe pin, while the ON position ties mPCIe pins and I/O cable pins together. In order to avoid interference and to keep 5V power from damaging your system board, it is important to set the DIP switch to correct positions before connecting the I/O cable.

Switching of internal/external GNSS and 1PPS signal is not controlled by DIP switch. Please see 10.8 1PPS for detailed instruction.

10. Design-in Guidelines

The SOM-352 pinout is compatible with most standard PCIe mini card interfaces. However, it may need to be fed with 5V DC power and connecting other I/O interfaces through an external cable when installed on an existing mPCIe system board. A customized PCIe mini card pinout can help user to get rid of the extra cable and to rely on the PCIe mini card interface alone. A design-in system board solution may provide improved reliability, simpler installation, and cost saving to the overall system.

10.1. Power Line Traces

• Power line traces should be as wide as possible, in order to reduce impedance of these lines.
• Crossing by any other lines of upper or lower layer should also be avoided.
• The maximum power consumption occurs during RF transmission. A typical transmitting frame lasts 1-2ms.
• It is recommended to keep the 5V supply current no less than 2A (continuous) to keep RF performance from degradation.
• If the SOM-352 halts or resets while performing a V2X RF transmission, it is recommended to add a bulk capacitor on the 5V trace near the mPCIe connector to lower the impedance of the 5V power rail.

10.2. Power Sequence

• 5V should be supplied prior to 3.3 Vaux.
• If 3.3 Vaux is fed before 5V, user should toggle the EX RSTn/PERST# signal after 5V is supplied.
• If it is intended to save power when the SOM-352 is not in use, it is suggested to pull low the EX RSTn/PERST# pin instead of cutting off 5V power. Once the EX RSTn/PERST# pin is pulled low, the SOM-352 will enter standby mode, and the power consumption will reduce to 10mA in about 10 seconds.

10.3. Brown Out

• If the 5V power supply drops below 3.5V, the SOM-352 will enter standby mode.
• A SOM in standby mode will stay in this mode until reset.
• Once the power supply returns to normal, the SOM-352 can reboot into normal operation with the rising edge of PERST# or EX RSTn signal.

10.4. Grounding

• Ensure good GND connection between the ground of the module and the ground of the system board.
• Grounding of the external components (e.g., capacitors) should be connected to the same reference ground of the module and not just on the top layer, use more than one via whenever possible to ensure good GND connection.

10.5. USB Data Lines

The SOM-352 mPCIe module includes a Universal Serial Bus (USB) transceiver, which operates at USB high-speed (480 Mbits/s). It is compliant with the USB 2.0 specification and can be used for control and data transfers as well as for diagnostic monitoring and firmware upgrade.

The USB port is typically the main interface between the SOM-352 mPCIe module and OEM hardware. Since the USB D+ and USB D- signals have a clock rate of 240 MHz, the signal traces must be routed carefully. Minimize trace lengths, number of vias, and capacitive loading.

The layout guidelines for the USB data lines (mPCIe pin 36, 38) is listed below. And a routing example for two pairs of USB data buses is shown in FIGURE 10: USB DATA LINE ROUTING EXAMPLE.

• The impedance value should be as close as possible to 90 Ohms differential.
• The differential pair signals should be all referenced to ground.
• Differential pair route in parallel and in equal length.
• The amount of vias and corners used for the USB signal layout should be minimized; this is to prevent the occurrence of reflection and impedance changes.
• Each pair of USB data lines is required to be parallel to each other with the same trace length, and not parallel with other signals to minimize crosstalk.
• Separate the signal traces into similar groups and route similar signal traces together. In addition, it is recommended to have differential pairs routed together on the system board.
• For the USB traces, do not route them under oscillators, crystals, clock synthesizers, magnetic devices or IC’s which could be using duplicate clocks.

10.6. Serial Port

The serial port is typically a secondary interface between the SOM-352 mPCIe module and OEM hardware. The level for SOM-352 UART is 3.3V TTL logic level.

Depending on the design of serial port on the OEM hardware, a level translator circuit might be needed to make the system operate properly (e.g., 5V to 3.3V or 1.8V to 3.3V). The only configuration that does not need level translation is the 3.3V UART.

10.7. Reset

The reset pin (PERST#, P22) is low active, and will reboot Linux when a rising edge of input voltage (end of assertion) is detected. The reset pin is internally connected to 3.3V with a 2KΩ pull-up resistor. Connecting this pin to an open drain or open collector driver is recommended if the motherboard logic level is different from 3.3V TTL.

10.8. 1PPS

The 1PPS pin (P49) serves as the input of an external 1PPS (1 pulse per second) signal. The start of a system time (UTC time) second will line up with the rising edge of this time pulse signal. For timing and logic level of external 1PPS signal, please see TABLE 2. RECOMMENDED OPERATING CONDITIONS. Leave this pin open if not used.

External 1PPS pins are exposed in both mPCIe interface pin 49 and I/O cable pin 5. To avoid back powering and latch-up, external 1PPS should be fed to SOM-352 at least 20ms later than SOM-352 power up.

The 1PPS input pins (mPCIe pin 49 and I/O cable pin 5) will be pulled high by default during boot-up (up to 200ms). If the 1PPS also serves as BOOT MODE pin in the external GNSS module, for example like some Teseo III modules, it may cause boot-up failure of the external GNSS module. If this happens, you may need choose one of the following three solutions:

1. Add a 3KΩ PD resistor on the motherboard side. (The internal PU resistance of SOM-352 is 32KΩ-60KΩ Ohm)
2. Delay the boot-up of external GNSS module for 200ms until SOM-352 boot-up completed.
3. Pull low the PERST#/EX RSTn signal during power up, and then release (or pull high) the PERST#/EX RSTn after the external GNSS module boot-up complete. The 1PPS pin (P49) will remain LOW until the release of PERST#/EX RSTn signal.

By default, the SOM-352 will use internal 1PPS signal. In order to change to external 1PPS and NMEA source, please issue the following commands in user space:

echo 100 > /sys/class/gpio/export
 echo out > /sys/class/gpio/gpio100/direction
 echo 0 > /sys/class/gpio/gpio100/value               # 0=Ext_GNSS, 1=Int_GNSS

To let the above setting take effect upon next boot-up, please append the above lines in /home/root/ext-fs/usr/bin/at_startup.

10.9. BOOTSTRP

The BOOTSTRP pin (P46) will be sampled during the first 10ms upon power up. If the BOOTSTRP is pulled HIGH (3.3V), the SOM-352 system will enter DFU (Device Firmware Upgrade) mode and allows the host system to flash the entire NAND via USB0 at once; otherwise, it will boot normally from NAND.

It is recommended to use a 0 Ohm resistor to pull-up the BOOTSTRP pin. The pull-up resistor of BOOTSTRP should not exceed 5 KOhm.

10.10. Tamper Detection (Optional)

The tamper detection function will be supported by project base. It is disabled by default. The SOM-352 has to be powered up for the tamper detection function to work. The design and implementation of a backup power source is not in the product scope and should be considered by the user.

The tamper detection mechanism is part of the FIPS 140-2 Level 3 security requirements. The tamper detection itself is carried out entirely in HW. On SW level, there is only an API that allows enabling the tamper detection mechanism. Calling this API will move tamper HW state from the testing mode to the production mode. Once called, it cannot move back to the testing mode.

The source and trigger mode of tamper detection signal can be selected with the DIP switch on SOM-352, position SW1.6 and SW1.7.

Tamper detection pins are exposed in both mPCIe interface pin 51 and I/O cable pin 6. Pulling the tamper detection pin to ground will trigger a tamper event, indicating that the enclosure of the system has been opened without proper authorization. User can enable one of the two tamper modes in API:

1. Production mode
2. Test mode.

10.10.1. Production Mode

In production mode, the SOM-352 will erase the CSP (critical security parameter) material saved in eHSM. The eHSM hardware will be left unusable because the CSP cannot be rewritten to the chip anymore. Two additional tamper modes are available when entering production mode: normal mode and standby mode.

10.10.1.1. Normal Mode

Tamper response provides protection against tamper attempts during operational state when the chip is powered on. When it is enabled, tamper event will immediately trigger the zeroization sequence. Enabling this mode is done by invoking the Enable Normal mode tamper response service API.

10.10.1.2. Standby Mode

Tamper response provides protection against tamper attempts while the chip is in sleep mode state. When it is enabled, any previously latched tamper event during sleep mode will trigger the zeroization sequence upon power-up. Enabling this mode is done by invoking the Enable standby mode tamper response service API.

10.10.2. Test Mode

In test mode, the SOM-352 will not erase the CSP (critical security parameter) material saved in eHSM. Each invocation of the tamper signal increments an internal counter within the eHSM. This counter can then be inquired by calling the eHSM runtime status API, providing evidence for the tamper signal detection.

10.11. Thermal Management

If performing heavy V2X transmission on SOM-352, it is recommended to add thermal vias and expose bare copper top layer on the system board to help disperse heat. Inserting a soft silicone thermally conductive pad between the system board and SOM-352 could facilitate heat dispersion to the system board more efficiently.

10.12. Firmware Upgrade

10.12.1. Manual control

When the mPCIe Pin 46 (BOOTSTRP) is left unconnected (floating) or connected to ground, the BOOT SW (SW1.8) controls the boot mode. See TABLE 11: DIP SWITCH FUNCTIONS for more details.

• BOOT SW ON: Normal boot (boot from NAND)
• BOOT SW OFF: Firmware upgrade (boot from USB0, DFU mode)

10.12.2. Host GPIO control

When the mPCIe Pin 46 (BOOTSTRP) connects to a host system GPIO, and the BOOTSW (SW1.8) is kept at ON position, the host system GPIO controls the boot mode. See TABLE 9: SOM-352 MINI PCIE ROW 1 PINOUT for more details.

• BOOTSTRP LO: Normal boot (boot from NAND)
• BOOTSTRP HI: Firmware upgrade (boot from USB0, DFU mode)

11. Dimensions and Weight

The SOM-352 module follows the PCIe full-mini card form factor, but 8.5mm wider than the standard 30mm width. When designing a system board, at least 3mm clearance on both left and right side is needed to avoid component interference. It is also recommended to reserve 13mm as total height limitation. Please refer to PCI Express Mini Card Electromechanical Specification 2.0/2.1 for more detailed guidelines.

It is recommended to use a mini PCIe connector with 4mm stack height, leaving 1.5mm space between the SOM-352 PCB and the system board. This space can later be filled with silicone thermal conductive pad to help dissipate the heat generated by SOM-352 to the system board PCB. User can choose TE 2041119-1 as a candidate for such a mini PCIe connector.

11.1. Component Keep Out Area

Maximum height of bottom side components may reach 1.0mm. In order to avoid interference with SOM-352, the system board side component height should be carefully considered according to the datasheet of mPCIe connector selected.

12. Software Settings

12.1. Unex BSP Interface Settings

The following BSP settings are applicable for Unex software package only.

12.2. Verifying the Integration with a Host System

The following descriptions are applicable for Unex software package only.

12.2.1. Windows 10/11

For verifying the integration of a SOM-352 with a Windows host system, please follow the steps below:

1. Install SOM-352 into a mini PCIe slot on a Windows host computer.
2. Check if a network adapter named “Remote NDIS Compatible Device” can be found in Device Manager.
3. Open Command Prompt on the Windows host.
4. Ping the RNDIS device IP of SOM-352 and check if it is alive.

   C:\Users\user> ping 192.168.1.3

5. Open a SSH terminal to SOM-352 and check if it works.

   C:\Users\user> ssh-keygen -R 192.168.1.3 & ssh [email protected]

For most Windows 10/11 systems, the RNDIS host driver is pre-installed by default. The Windows host will assign a default IP 192.168.1.1 to this new RNDIS network adapter. This default host IP address is configured in /etc/network/udhcpd.conf on the SOM-352 filesystem and can be modified if needed.

12.2.2. Linux

For verifying the integration of a SOM-352 with a Linux host system, please follow the steps below:

1. Install SOM-352 into a mini PCIe slot on a Linux host computer.
2. Open terminal on the Linux host.
3. Check if the RNDIS driver has already been installed on the host system. If it has not been installed yet, install the RNDIS driver for the host system. The driver installation might include loading rndis_host.ko with modprobe command or enabling CONFIG_USB_NET_RNDIS_HOST when compiling the Linux kernel. The detailed instructions of installing the RNDIS driver are not included here because it may vary from one distribution to another.

   user@host:~$ lsmod | grep rndis

4. Check if the Unex device has been registered as a RNDIS device with a network interface.

   user@host:~$ dmesg | grep -i -C4 unex

5. Ping the RNDIS device IP of SOM-352 and check if it is alive.

   user@host:~$ ping 192.168.1.3

6. Open a SSH terminal to SOM-352 and check if it works.

   user@host:~$ ssh-keygen -R 192.168.1.3 ; ssh [email protected]

For most desktop Linux distributions, the RNDIS host driver is installed by default. The Linux host will assign a default IP 192.168.1.1 to this new RNDIS network adapter. This default host IP address is configured in /etc/network/udhcpd.conf on the SOM-352 filesystem and can be modified if needed.

13. Troubleshooting

13.1. No Response After Applying Power

This phenomenon may come from multiple causes. Please follow the steps below to check each one of them:

1. Check if the 5V/3.3V power have been properly supplied by your motherboard.
2. Check if the SW1.1 setting matches your hardware configuration.
3. Check if the SW1.8 setting is at ON (Boot from NAND) position.
4. Connect the UART console to your host.
   1. If you have a design-in UART interface in mPCIe P17/P19, make sure to keep the SW1.2/SW1.3 at ON position.
   2. If you do not have design-in UART, please connect the I/O cable for UART interface and keep the SW1.2/SW1.3 at OFF position.
5. Check if the RNDIS driver has been properly installed on your host system.
6. Check if the IP address 192.168.1.1 has been assigned to another network interface on your host system. If it has already been assigned, it is required to perform either of the following operations:
   1. Change the IP setting of that network interface on your host system and leave 192.168.1.1 available for the SOM-352 family RNDIS interface.
   2. Change the SOM-352 family RNDIS IP address setting. Please refer to the CHANGING SYSTEM IP ADDRESS section in Unex’s documentation, which can be found in Unex’s software release package.

13.2. No TX/RX Activities during Over-the-Air Testing

1. Check the antenna status of both V2X antennas on the TX node and the Rx node.
   1. If Unex’s V2X antennas EX-55/EX-53 are used, use the V2X antenna detection commands listed in TABLE 13: UNEX BSP INTERFACE SETTINGS. For OPEN/SHORT value range, please see TABLE 5: V2X ANTENNA STATUS.

      cat /sys/bus/iio/devices/iio\:device0/in_voltage4_raw

      cat /sys/bus/iio/devices/iio\:device0/in_voltage5_raw

   2. If Unex’s V2X antennas EX-55/EX-53 are not used, it is the user’s responsibility to check the antenna OPEN/SHORT status.

      Attention	Performing transmission under OPEN/SHORT conditions may cause permanent damages to RF components. Always check antenna status before any V2X TX activity.

2. For DSRC systems:
   1. Send 10 V2X packets with priority 7 in TX node.

      diag-cli <<< $'chan freq 0 5860\nv2x send 0 0 0 400 10 10 7 160\nstats\nexit' 2>/dev/null

      
   2. Check MAC/PHY statistics in RX node

      diag-cli <<< $'chan freq 0 5860\nstats\nexit' 2>/dev/null

      
3. For C-V2X systems
   1. Check GNSS antenna and GNSS health status. C-V2X requires GNSS time synchronization and TSF (Timing synchronization function) synchronization with GNSS 1PPS before any transmission.
      1. Make sure the very same /usr/bin/cv2x_rrc_config.uper and /usr/bin/cv2x_sw_config.txt are uploaded on both TX and RX nodes.
      2. If the SOM-352 comes with Unex’s C-V2X protocol stack, then use gnss_health command to check the overall GNSS system healthiness. ACL_TIME_SYNC_SYNCED means the access layer (i.e., the TSF timer) has been successfully synchronized.
      3. If the SOM-352 comes without Unex’s C-V2X protocol, then use the following commands.
         1. Check the GNSS antenna status and fix mode. cat /sys/bus/iio/devices/iio\:device0/in_voltage1_raw

            For GNSS antenna status, please see TABLE 6: GNSS ANTENNA STATUS; for GNSS fix mode, please check the 2^nd field of GSA sentence: $GNGSA,A,3,24,15,10,23,12,32,,,,,,,2.6,1.4,2.1*2E

            FFix Mode: 1 = Fix not available; 2 = 2D fix; 3 = 3D fix.

         2. Check 1PPS status watch -n 1 grep pps /proc/interrupts

            If the pps1.-1 count is increasing, then the 1PPS is working.

         3. Check TSF synchronization status diag-cli <<< 'ddm tsf get' 2>/dev/null | grep =

            If it shows TSF lock status = locked, then TSF is synchronized.

   2. If the SOM-352 comes with Unex’s C-V2X protocol, stop Unex’s V2X services on both TX and RX nodes before running cgen command

      d=/etc/runit/svdir/;svstop(){ [ -e $d$s ] && sv stop $d$s; }; for s in v2xcastd ssmed ssmd dot3d gnd;do svstop;done

   3. Clear MAC/PHY statistics on the RX node cd /usr/bin;cgen freq=5915 run=cyq 2>/dev/null
   4. Send 10 V2X packets from the TX node

      cd /usr/bin;cgen power=40 freq=5915 num=10 run=wwwcgtwzq 2>/dev/null

      
   5. Check MAC/PHY statistics on the RX node

      cd /usr/bin;cgen freq=5915 run=yq 2>/dev/null