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