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README

1================================================================================
2Useful notes on bulding and using of U-Boot on ARC EM Development Kit (AKA EMDK)
3================================================================================
4
5   BOARD OVERVIEW
6
7   The DesignWare ARC EM Development Kit is FPGA-bases platform for rapid
8   software development on the ARC EM family of processors.
9
10   Since this board is based on FPGA it's possible to load and use different
11   versions of ARC EM CPUs. U-Boot is built to be run on the simplest
12   possible configuration which means the same one binary will work on more
13   advanced configurations as well.
14
15   The board has the following features useful for U-Boot:
16    * On-board 2-channel FTDI TTL-to-USB converter
17      - The first channel is used for serial debug port (which makes it possible
18        to use a serial connection on pretty much any host machine be it
19        Windows, Linux or Mac).
20        On Linux machine typucally FTDI serial port would be /dev/ttyUSB0.
21        There's no HW flow-control and baud-rate is 115200.
22
23      - The second channel is used for built-in Digilent USB JTAG probe.
24        That means no extra hardware is required to access ARC core from a
25        debugger on development host. Both proprietary MetaWare debugger and
26        open source OpenOCD + GDB client are supported.
27
28      - Also with help of this FTDI chip it is possible to reset entire
29        board with help of a special `rff-ftdi-reset` utility, see:
30        https://github.com/foss-for-synopsys-dwc-arc-processors/rff-ftdi-reset
31
32    * Micro SD-card slot
33      - U-Boot expects to see the very first partition on the card formatted as
34        FAT file-system and uses it for keeping its environment in `uboot.env`
35        file. Note uboot.env is not just a text file but it is auto-generated
36        file created by U-Boot on invocation of `saveenv` command.
37        It contains a checksum which makes this saved environment invalid in
38        case of maual modification.
39
40      - There might be more useful files on that first FAT partition like
41        user applications, data files etc.
42
43    * 256 KiB of "ROM"
44      - This so-called "ROM" is a part of FPGA image and even though it
45        might be unlocked for writes its initial content will be restored
46        on the next power-on.
47
48
49   BUILDING U-BOOT
50
51   1. Configure U-Boot:
52      ------------------------->8----------------------
53      make emdk_defconfig
54      ------------------------->8----------------------
55
56   2. To build Elf file (for example to be used with host debugger via JTAG
57      connection to the target board):
58      ------------------------->8----------------------
59      make mdbtrick
60      ------------------------->8----------------------
61
62      This will produce `u-boot` Elf file.
63
64   3. To build binary image to be put in "ROM":
65      ------------------------->8----------------------
66      make u-boot.bin
67      ------------------------->8----------------------
68
69
70   EXECUTING U-BOOT
71
72   1. The EMDK board is supposed to auto-start U-Boot image stored in ROM on
73      power-on. For that make sure VCCIO DIP-switches are all in "off" state.
74
75   2. Though it is possible to load U-Boot as a simple Elf file via JTAG right
76      in "ROM" and start it from the debugger. One important note here we first
77      need to enable writes into "ROM" by writing 1 to 0xf0001000.
78
79      2.1. In case of proprietary MetaWare debugger run:
80      ------------------------->8----------------------
81      mdb -dll=opxdarc.so -OK -preloadexec="eval *(int*)0xf0001000=0" u-boot
82      ------------------------->8----------------------
83