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- ================================================================================
- Useful notes on bulding and using of U-Boot on
- ARC IoT Development Kit (AKA IoTDK)
- ================================================================================
- BOARD OVERVIEW
- The DesignWare ARC IoT Development Kit is a versatile platform that includes
- the necessary hardware and software to accelerate software development and
- debugging of sensor fusion, voice recognition and face detection designs.
- The ARC IoT Development Kit includes a silicon implementation of the
- ARC Data Fusion IP Subsystem running at 144 MHz on SMIC's
- 55-nm ultra-low power process, and a rich set of peripherals commonly used
- in IoT designs such as USB, UART, SPI, I2C, PWM, SDIO and ADCs.
- The board is shipped with pre-installed U-Boot in non-volatile memory
- (eFlash) so on power-on user sees U-Boot start header and command line
- prompt which might be used for U-Boot environment fine-tuning, manual
- loading and execution of user application binaries etc.
- The board has the following features useful for U-Boot:
- * On-board 2-channel FTDI TTL-to-USB converter
- - The first channel is used for serial debug port (which makes it possible
- to use a serial connection on pretty much any host machine be it
- Windows, Linux or Mac).
- On Linux machine typucally FTDI serial port would be /dev/ttyUSB0.
- There's no HW flow-control and baud-rate is 115200.
- - The second channel is used for built-in Digilent USB JTAG probe.
- That means no extra hardware is required to access ARC core from a
- debugger on development host. Both proprietary MetaWare debugger and
- open source OpenOCD + GDB client are supported.
- - Also with help of this FTDI chip it is possible to reset entire
- board with help of a special `rff-ftdi-reset` utility, see:
- https://github.com/foss-for-synopsys-dwc-arc-processors/rff-ftdi-reset
- * Micro SD-card slot
- - U-Boot expects to see the very first partition on the card formatted as
- FAT file-system and uses it for keeping its environment in `uboot.env`
- file. Note uboot.env is not just a text file but it is auto-generated
- file created by U-Boot on invocation of `saveenv` command.
- It contains a checksum which makes this saved environment invalid in
- case of maual modification.
- - There might be more useful files on that first FAT partition like
- user applications, data files etc.
- * USB OTG connector
- - U-Boot may access USB mass-storage devices attached to this connector.
- Note only FAT file-system is supported. It might be used for storing
- user application binaries as well as micro SD-card mentioned above.
- * The following memories are avaialble on the board:
- - eFlash: 256 KiB @ 0x0000_0000
- A non-volatile memory from which ARC core may execute code directly.
- Still is is not direcly writable, thus this is not an ordinary RAM.
- - ICCM: 256 KiB @ 0x2000_0000
- Instruction Closely Coupled Memory - fast on-chip memory primary used
- for code being executed, still data could be placed in this memory too.
- In that sense it's just a general purpose RAM.
- - SRAM: 128 KiB @ 0x3000_0000
- On-chip SRAM. From user perspective is the same as ICCM above.
- - DCCM: 128 KiB @ 0x8000_0000
- Data Closely Coupled Memory is similar to ICCM with a major difference -
- ARC core cannot execute code from DCCM. So this is very special RAM
- only suitable for data.
- BUILDING U-BOOT
- 1. Configure U-Boot:
- ------------------------->8----------------------
- make iot_devkit_defconfig
- ------------------------->8----------------------
- 2. To build Elf file (for example to be used with host debugger via JTAG
- connection to the target board):
- ------------------------->8----------------------
- make mdbtrick
- ------------------------->8----------------------
- This will produce `u-boot` Elf file.
- 3. To build binary image to be put in "ROM":
- ------------------------->8----------------------
- make u-boot.bin
- ------------------------->8----------------------
- EXECUTING U-BOOT
- 1. The IoTDK board is supposed to auto-start U-Boot image stored in eFlash on
- power-on. Note it's possible to update that image - follow instructions in
- user's manual.
- 2. Though it is possible to load and start U-Boot as a simple Elf file
- via JTAG right in ICCM. For that it's required to re-configure U-Boot
- so it gets linked to ICCM address 0x2000_0000 (remember eFlash is not
- direcly writable).
- Run U-Boot's configuration utility with "make menuconfig", go to
- "Boot images" and change "Text Base" from default 0x00000000 to
- 0x20000000. Exit & save new configuration. Now run "make mdbtrick" to
- build new Elf.
- 2.1. In case of proprietary MetaWare debugger run:
- ------------------------->8----------------------
- mdb -digilent u-boot
- ------------------------->8----------------------
- USING U-BOOT
- Note due to limited memory size it's supposed that user will run binary
- images of their applications instead of loading Elf files.
- 1. To load and start application binary from micro SD-card execute
- the following commands in U-Boot's shell:
- ------------------------->8----------------------
- fatload mmc 0 0x20000000 yourapp.bin
- go 0x20000000
- ------------------------->8----------------------
- 2. To load and start application binary from USB mass-storage device execute
- the following commands in U-Boot's shell:
- ------------------------->8----------------------
- usb start
- fatload usb 0x20000000 yourapp.bin
- go 0x20000000
- ------------------------->8----------------------
- 3. To have a sequence of commands executed on U-Boot start put those
- commands in "bootcmd" with semicolon between them.
- For example to get (1) done automatically:
- ------------------------->8----------------------
- setenv bootcmd fatload mmc 0 0x20000000 yourapp.bin\; go 0x20000000
- saveenv
- ------------------------->8----------------------
- 4. To reboot the board just run:
- ------------------------->8----------------------
- reset
- ------------------------->8----------------------
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