| ================================================================================ |
| 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---------------------- |
