Frequently Asked Questions¶
- Table of contents
- Frequently Asked Questions
- How can I use the TPS62519 PMIC to Power Down the module?
- If I have powered down the PMIC, how can I power it back on?
- How can I turn off the LEDs on the SOM?
- Will the RTC on the AM62x/AM62A processor keep time if the SOM is powered off?
- What do GP, HS-FS, and HS-SE mean in TI's Documentation?
- My console is littered with "audit: type=<blah>..." messages
- wpa_supplicant fails to start
- What is the difference between the MitySOM-AM62 and the MitySOM-AM62A?
This section outlines common questions regarding the MitySOM-AM62x module.
*Please also see https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1220040/faq-am62x-am62ax-am62p-frequently-asked-questions-list *
How can I use the TPS62519 PMIC to Power Down the module?¶
The TPS62519 PMIC can be used to completely shut down all of the supplies feeding the SOM AM62x processor, DDR4, OSPI (if installed), and eMMC (if installed).
There are two mechanisms to shut down the power:
- From software, issue the poweroff command.
- Pull the PMIC_EN_PB (pin 40 on the SO DIMM DDR4 connector) low. This will interrupt the AM62x with a notification that power down is requested.
Both of these scenarios will cause the ARM to gracefully shutdown the operating system and issue a command the TPS65219 PMIC to power down via the I2C0 bus.
If I have powered down the PMIC, how can I power it back on?¶
Issue a "long press" (pull the signal low for at least 3 seconds) on the PMIC_EN_PB (pin 40) signal. This will cause the PMIC to power the SOM AM62x and on-board peripherals back on, effectively causing a power on sequence to the module.
How can I turn off the LEDs on the SOM?¶
There are two LED's on the SOM. The first LED, D1, is a DEBUG LED that can be controlled via the I2C BUS on the PMIC. From u-Boot, you can disable the LED with the following command:
=> i2c dev 0 => i2c mw 30 1e 06
You can also turn it back on with the following command:
=> i2c dev 0 => i2c mw 30 1e 02
Refer to Controlling the SOM Debug LED D1 link for instructions on controlling D1 from linux.
The second LED, D2, is a power good indicator. This LED will always light when +3.3V is provided to the power interface on the SOM and PMIC has determined it is within the specified operating range for the part. However, the LED return (connection to kathode), is available on Pin 2 of the SOM SODIMM connector. Normally, connecting this to ground will cause the LED to illuminate as described. When the pin is disconnected from ground, then the LED will not light up as there is no current path for the LED.
Will the RTC on the AM62x/AM62A processor keep time if the SOM is powered off?¶
No. The RTC that is included in the AM62x/AM62Ax processor is driven with a local 32KHz reference clock and may be used to keep accurate time once it is set. In addition to basic timekeeping, the RTC may be used to set alarms and wake the processor up when it is put into the sleep mode power states. I.e., the onboard RTC will maintain time when entering and exiting sleep states, which is a normal use case for mobile applications.
It is not possible to power the AM62x/AM62Ax RTC with an external battery in the situation where the +3.3V power input to the SOM is removed (e.g., turning off the power switch on the MitySOM-AM62 DevKit) or the PMIC is commanded to power down the system (e.g., issuing the poweroff command mentioned above). For applications that need to maintain time while the SOM is powered down, Critical Link recommends adding an I2C based real-time clock chip and appropriately sized coin cell battery on a carrier card.
What do GP, HS-FS, and HS-SE mean in TI's Documentation?¶
These acronyms refer to the type of boot security built-in to the AM62 processor included on the MitySOM-AM62.
| GP | General Purpose: This is a SoC/board state where there is no device protection and authentication is not enabled for booting the device. |
| HS-FS | High Security - Field Securable: This is a SoC/board state before a customer has blown the keys in the device. i.e. the state at which HS device leaves TI factory. In this state, the device protects the ROM code, TI keys and certain security peripherals. In this state, device do not force authentication for booting, however DMSC is locked. |
| HS-SE | High Security - Security Enforced: This is a SoC/board state after a customer has successfully blown the keys and set “customer Keys enable”. In HS-SE device all security features enabled. All secrets within the device are fully protected and all of the security goals are fully enforced. The device also enforces secure booting. |
Early versions of the MitySOM-AM62 use "GP" variants but eventually TI will only ship HS-FS variants. Please contact Critical Link if you need help with identifying your particular processor type. If you received your MitySOM-AM62 in 2024 or later, you most likely have a HS-FS processor.
Early customers of the MitySOM-AM62 with GP processors could run into compatibility issues when using files from newer TI Processor SDKs or Critical Link binaries that are meant to run on HS-FS variants. Please post any related questions in our forum for assistance with your particular application.
TI has also provided a discussion of workarounds and changes related to the transition from GP to HS-FS: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1210443/faq-am625-generating-sitara-am62x-am62ax-am64x-gp-device-bootable-mmc-sd-card-images-using-sdk-v8-6-and-yocto
My console is littered with "audit: type=<blah>..." messages¶
Since SDK9.0, kernel AUDIT framework is enabled by default, which makes the kernel print these messages.
If these messages affect using the Linux console, you can disable it by adding the following line in file uEnv.txt in the SD card boot partition, where the U-Boot binaries are located.
optargs="audit=0"
wpa_supplicant fails to start¶
If you see error messages regarding unknown global field and/or Invalid configuration line for the following settings:- p2p_go_ht40
- p2p_ignore_shared_freq
When starting the wifi subsystem with the commands in /usr/share/wl18xx, you can edit the /usr/share/wl18xx/wpa_supplicant.conf file and comment the offending lines out.
These settings are dependent on the configuration of the WiFi HW and SW, so may not work on your system when using the prebuild wpa_supplicant.
What is the difference between the MitySOM-AM62 and the MitySOM-AM62A?¶
The AM62A processor provides additional features including:- Single-core Arm® Cortex®-R5F at up to 800 MHz (the AM62 has a Single-core Arm® Cortex®-M4F MCU at up to 400 MHz)
- Single-core Arm® Cortex®-R5F at up to 800 MHz, integrated to support Device Management
- Deep Learning Accelerator based on Single-core C7x
- C7x floating point, up to 40 GFLOPS, 256-bit Vector DSP at 1.0 GHz
- Matrix Multiply Accelerator (MMA), up to 2TOPS (8b) at 1.0 GHz
- Vision Processing Accelerators (VPAC) with Image Signal Processor (ISP) and multiple vision assist accelerators:
- 315 MPixel/s ISP; Up to 5MP @ 60 fps
- Support for 12-bit RGB-IR
- Output color format : 8-bits, 12-bits, and YUV 4:2:2, YUV 4:2:0, RGB, HSV/HSL
- There are no direct OLDI outputs available on the AM62A Processor. Displays must use the VOUT0 display output option.
- There are no provisions for OpenGL hardware acceleration.
TI provides datasheets for each Processor for comparison:
AM62: https://www.ti.com/lit/ds/symlink/am625.pdf
AM62A: https://www.ti.com/lit/ds/symlink/am62a7.pdf
If you have further questions, please contact Critical Link and we will help you pick the best MitySOM for your application.
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