Introduction

SoC's such as J721E/J7200, integrates a MicroController Unit Subsystem (MCU SS) as a chip-in-chip. It operates using a separate voltage supply, clock sources and resets and includes the components needed for device management. This allows the MCUSS to function continuously regardless of the state of the rest of the device.

This application demonstrates steps to switch mode from ACTIVE (full SoC powered ON) to MCU Only mode and then from MCU Only to ACTIVE mode on J721E EVM.

Table below lists acronyms for different modes of the device

Mode	Comments
MCU Only	Power to main domain is turned OFF and no compute core/hardware accelerators can be used. MCU domain is functional
ACTIVE	Main and MCU domains are functional

Table below list SoC on which this demo application is supported and tested

SoC	Comments
J721E	Requires beta j721e evm with TPS6594-Q1 PMIC

References

The application note (Link), details steps required to power SoC with PMIC TPS6594-Q1
J721E Schematics / Layout (Link)

Dependencies

This application depends on multiple components and are detailed in sections below

MCUSW Demo : Uses Boot App to start application on compute core and mode switch app on MCU 10
PDK : Uses I2C driver to control & Configure PMIC
TI RTOS : Uses Task
UNIFLASH Utility - To flash binaries into on-board flash UNIFLASH ON TI.COM
JTAG : When in MCU ONLY mode JTAG would be powered down, recommend not to use CCS to execute this application
OSCILLOSCOPE : Required to test / check voltage at test points (TP)

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Flow Chart

The application MCU ONLY Task is hosted on MCU R5F and switches the SoC between ACTIVE and MCU ONLY modes.

Flow Chart

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Build Instructions

This application is part of Boot App and is disabled by default and requires to be enabled.

Enabling the application

In file (MCUSW Install Dir)/mcuss_demos/boot_app_mcu_rtos/makefile
The MCUONLYFUNC controls enabling/disabling of this application
Set MCUONLYFUNC to enabled i.e. MCUONLYFUNC ?= enabled

Building

Follow the instructions specified in Boot App - Build Instructions

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Steps to run

Steps to run is detailed in Boot App - Steps to run

J721E:

coresdk_rtos_jacinto_xx_yy_xx_bb/pdk_jacinto_07.x.x/packages/ti/boot/sbl/binary/j721e_evm/cust/bin/sbl_cust_img_mcu1_0_release.tiimage @ 0
coresdk_rtos_jacinto_xx_yy_xx_bb/pdk_jacinto_07.x.x/packages/ti/drv/sciclient/soc/V1/tifs.bin @ 80000
coresdk_rtos_jacinto_xx_yy_xx_bb/mcusw/binary/can_boot_app_mcu_rtos/bin/j721e_evm/can_boot_app_mcu_rtos_mcu1_0_release.appimage @ 100000
coresdk_rtos_jacinto_xx_yy_xx_bb/mcusw/mcuss_demos/boot_app_mcu_rtos/main_domain_apps/binary/bin/j721e_evm/multicore_MCU2_0_MCU2_1_stage1.appimage @ 1fc0000
coresdk_rtos_jacinto_xx_yy_xx_bb/mcusw/mcuss_demos/boot_app_mcu_rtos/main_domain_apps/binary/bin/j721e_evm/multicore_DSPs_MCU3_0_MCU3_1_stage2.appimage @ 27c0000
coresdk_rtos_jacinto_xx_yy_xx_bb/mcusw/mcuss_demos/boot_app_mcu_rtos/main_domain_apps/binary/bin/j721e_evm/multicore_MPU1_0_stage3.appimage @ 37c0000

Important points to note
- Ensure UART / Serial port is not connected while programming flash
- BOOT Mode
  - UART Boot Mode : SW8: 0000_0000, SW9: 0111_0000
  - OSPI Boot Mode : SW8: 0000_0000, SW9: 0100_0000
- When in MCU Only JTAG would be disconnected

Check power rails

When operating in ACTIVE mode or MCU only mode, one could check power supply provided on different rails. The table below list different test-point/power rails that could be probed

Mode	Test Point	Expected Voltage
ACTIVE	TP133	1.8v
ACTIVE	TP134	1.8v
MCU Only	TP133	1.8v
MCU Only	TP134	0.0v

TPs Highlighted

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LOGs

Below is the log from one of the test runs

Starting Sciserver..... PASSED
MCN Response App:NOTE : Operating in internal loop-bacCAN Response App:NOTE : Operating in internal loop-back mode
CAN Response App:Message Id Received c00000c0 Message Length is 64
CAN Response App:Test completed for 0 instance
CAN Response App:NOTE : Operating in internal loop-back mode
CAN Response App:Message Id Received c00000b0 Message Length is 64
C OSPI NOR device ID: 0x5b1a, manufacturer ID: 0x2c
Length is 64
CAN Response App:Test completed for 1 instance
CAN Response App:Test completed for 1 instance
CAN Response App: 8192 bytes used for stack
CAN Response App:Early CAN completed!!!
Boot App: Started at 479 usec
Boot App: Total Num booted cores = 8
Boot App: Booted Core ID #6 at 198915 usecs
Boot App: Booted Core ID #7 at 199123 usecs
Boot App: Booted Core ID #8 at 266195 usecs
Boot App: Booted Core ID #9 at 266400 usecs
Boot App: Booted Core ID #10 at 266594 usecs
Boot App: Booted Core ID #11 at 266774 usecs
Boot App: Booted Core ID #12 at 267433 usecs
Boot App: Booted Core ID #0 at 296580 usecs
MCU Boot Task started at 478 usecs and finished at 4938455 usecs
MCU only app: BootApp Task to completed!
MCU only app: Inside MCU ONLY task!
MCU only app: Disabling MAXT_OUTRG_EN for TMPSENS1:4 in MAIN domain!
MCU only app: STATE INFO :: CURRENTLY IN ACTIVE MODE!
MCU only app: LED LD5 should be ON
MCU only app: Sleeping for 5s, please measure TP133 and TP134!
MCU only app: Expected values in ACTIVE mode:
TP133: HIGH
TP134: HIGH
MCU only app: ############################ACTIVE -> MCU ONLY MODE############################
MCU only app: Issueing a SW reset to the MAIN domain...
MCU only app: PMIC STATE CHANGE: ACTIVE -> MCU ONLY...
MCU only app: INT_TOP = 0xc
MCU only app: INT_STARTUP = 0x2
MCU only app: INT_GPIO = 0xa
MCU only app: INT_GPIO1_8 = 0xc8
MCU only app: Read FSM_NSLEEP_TRIGGERS = 0x0
MCU only app: Write FSM_NSLEEP_TRIGGERS = 0x2
MCU only app: Read FSM_NSLEEP_TRIGGERS = 0x2
MCU only app: Write INT_STARTUP = 0x2
MCU only app: INT_TOP = 0x4
MCU only app: Write INT_STARTUP = 0xc8
MCU only app: INT_GPIO = 0x2
MCU only app: INT_TOP = 0x4
MCU only app: Write INT_GPIO = 0x2
MCU only app: Final Read INT_TOP = 0x0
MCU only app: Final Read FSM_NSLEEP_TRIGGERS = 0x2
MCU only app: PMIC STATE CHANGE: ACTIVE -> MCU ONLY...Done
MCU only app: #########################ACTIVE -> MCU ONLY MODE DONE##########################
MCU only app: STATE INFO :: NOW IN MCU ONLY MODE!
MCU only app: LED LD5 should be OFF
MCU only app: Sleeping for 5s, please measure TP133 and TP134!
MCU only app: Expected values in MCU ONLY mode:
TP133: HIGH
TP134: LOW
MCU only app: ############################MCU ONLY -> ACTIVE MODE############################
MCU only app: PMIC STATE CHANGE: MCU ONLY -> ACTIVE...
MCU only app: INT_TOP = 0x0
MCU only app: Write CONFIG_1 = 0xc0
MCU only app: Write FSM_NSLEEP_TRIGGERS = 0x3
MCU only app: Write CONFIG_1 = 0x0
MCU only app: Read FSM_NSLEEP_TRIGGERS = 0x3
MCU only app: PMIC STATE CHANGE: MCU ONLY -> ACTIVE...Done
MCU only app: Configure WKUPMCU2MAIN and MAIN2WKUPMCU Bridges...
MCU only app: WKUPMCU2MAIN and MAIN2WKUPMCU Bridges configured successfully!
MCU only app: Configuring Sciclient_board for MAIN domain
MCU only app: Initiallizing MAIN PLLS...
MCU only app: Initiallizing MAIN CLOCKS...
MCU only app: Initiallizing DDR...
MCU only app: Trying to access MAIN domain peripherals...
MCU only app: Writing to DDR...
MCU only app: Reading from DDR...
MCU only app: Read value matches the value written for DDR!
MCU only app: Writing to MSMC...
MCU only app: Reading from MSMC...
MCU only app: Read value matches the value written for MSMC!
MCU only app: Reading MAIN MCAN0 Revision register...
MCU only app: MAIN MCAN0 MCANSS_PID = 0x68e04901
MCU only app: #########################MCU ONLY -> ACTIVE MODE DONE##########################
MCU only app: STATE INFO :: CURRENTLY IN ACTIVE MODE!
MCU only app: LED LD5 should be ON
MCU only app: Expected values in ACTIVE mode:
TP133: HIGH
TP134: HIGH
MCU only app: Enterting an infinite loop...
MCU only app: As the full chip is powered ON you can connect JTAG
MCU only app: Connect CCS via JTAG at this point and access DDR, MSMC and other MAIN domain perepherals (eg - MCAN)!!

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Known Issues

When switching from MCU ONLY mode back to ACTIVE mode, currently loading of firmares on the MAIN domain cores is not supported.

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Document Revision History

Revision	Date	Author	Description	Status
0.1	12 Jan 2021	Sujith S	Initial Version	Approved