__   _ __      _______  _____            __
        / /  (_) /____ / __/ _ \/ ___/__ ________/ /
       / /__/ / __/ -_)\ \/ // / /__/ _ `/ __/ _  /
      /____/_/\__/\__/___/____/\___/\_,_/_/  \_,_/

          Copyright 2017-2018 / LambdaConcept
          Copyright 2017-2018 / EnjoyDigital

       A small footprint and configurable SDCard core
                powered by LiteX & Migen

[> Intro
--------
LiteSDCard is a small footprint and configurable SDCard core.

LiteSDCard is part of LiteX libraries whose aims are to lower entry level of
complex FPGA cores by providing simple, elegant and efficient implementations
of components used in today's SoC such as Ethernet, SATA, PCIe, SDRAM Controller...

Using Migen to describe the HDL allows the core to be highly and easily configurable.

LiteSDCard can be used as LiteX library or can be integrated with your standard
design flow by generating the verilog rtl that you will use as a standard core.

[> Features
-----------
PHY:
  - Xilinx Spartan 6 and 7-Series FPGA
  - optional clock feedback (UHS-I)
Core:
  - Command & Data CRC inserters/checkers
  - Single and multiple blocks write/read
  - Errors detection and reporting
  - Dynamically configurable clock speed
Frontend:
  - Synthetizable BIST
  - 32 <--> 8 bits stream converters

[> Performances
---------------
SD0: Good RAM 8GB (cheap SD Card)
SD1: SanDisk Ultra 32GB
SD2: SanDisk Extreme 128GB

W/R(MB/s) performance vs SD frequency:

    | 20MHz | 40MHz | 75MHz | 100MHz | 125MHz
SD0 |  4/9  | 6/18  |  7/33 |   7/44 |  7/56
SD1 |  6/9  | 9/18  | 12/33 |  14/44 | 15/56
SD2 |  9/9  | 18/18 | 33/33 |  43/44 | 54/55

[> Possible improvements
------------------------
- add standardized interfaces (AXI, Avalon-ST)
- add vendor agnostic phy for low speeds
- add support for Altera FPGAs.
- add support for Lattice FPGAs.
- add Zynq Linux drivers.
- ... See below Support and consulting :)

If you want to support these features, please contact us.

[> Getting started
------------------
1. Install Python 3.5, Migen and FPGA vendor's development tools.
   Get Migen from: https://github.com/m-labs/migen

2. Obtain LiteX and install it:
  git clone https://github.com/enjoy-digital/litex --recursive
  cd litex
  python3 setup.py develop
  cd ..

3. Build and load Arty test design:
  go to examples
  run ./arty.py cpu

4. Build firmware:
  go to litesdcard/firmware
  make all

5. Load firmware:
  litex_term --kernel firmware.bin <your_serial_port>

6. Test firmware:
  sdclk 10
  sdinit
  sdtest 8

[> License
----------
LiteSDCard is released under the very permissive two-clause BSD license. Under the
terms of this license, you are authorized to use LiteSDCard for closed-source
proprietary designs.
Even though we do not require you to do so, those things are awesome, so please
do them if possible:
 - tell us that you are using LiteSDCard
 - cite LiteSDCard in publications related to research it has helped
 - send us feedback and suggestions for improvements
 - send us bug reports when something goes wrong
 - send us the modifications and improvements you have done to LiteSDCard.

[> Support and consulting
-------------------------
We love open-source hardware and like sharing our designs with others.

LiteSDCard is developed and maintained by LambdaConcept & EnjoyDigital.

If you would like to know more about LiteSDCard or if you are already a happy user
and would like to extend it for your needs, EnjoyDigital can provide standard
commercial support as well as consulting services.

So feel free to contact us, we'd love to work with you! (and eventually shorten
the list of the possible improvements :)

[> Contact
----------
E-mail:
po [AT] lambdaconcept.com
ramtin [AT] lambdaconcept.com
florent [AT] enjoy-digital.fr