programming.rst

SDRAM Programming Guide

This section provides information on how to program applications using the SDRAM module.

SDRAM Default implementation

For convenience the module_sdram can use a default implementation. When the define SDRAM_DEFAULT_IMPLEMENTATION is set in sdram_conf.h to one of the supported targets then the sdram_server function will act as a call to the specified implementation. The same applies for the sdram_ports structure. The currently supported targets are:

• PINOUT_V2_IS42S16400F - This corresponds to the ISSI part IS42S16400F in a 21 pin configuration.
• PINOUT_V1_IS42S16400F - This corresponds to the ISSI part IS42S16400F in a 20 pin configuration.
• PINOUT_V1_IS42S16160D - This corresponds to the ISSI part IS42S16160D in a 20 pin configuration.
• PINOUT_V0 - This is for a legacy 22 pin configuration.

See the individual port.h files to find the port configurations.

Single SDRAM Support

For a application with a single SDRAM the default implementation should be set. If it is not set then the explicit sdram_server and sdram_ports must be used. The same applied for all the implementation specific defines.

Multiple Homogeneous SDRAM Support

For a application with a single SDRAM the default implementation should be set. For example, to drive two IS42S16400F parts, set the SDRAM_DEFAULT_IMPLEMENTATION to PINOUT_V1_IS42S16400F then the following will create the servers:

chan c,d;
par {
        sdram_server(c, ports_0);
        sdram_server(d, ports_1);
        app_0(c);
        app_1(d);
}

and the ports for the above would have been created by:

struct sdram_ports ports_0 = {
        XS1_PORT_16A,
        XS1_PORT_1B,
        XS1_PORT_1G,
        XS1_PORT_1C,
        XS1_PORT_1F,
        XS1_CLKBLK_1
};
struct sdram_ports ports_1 = {
        XS1_PORT_16B,
        XS1_PORT_1J,
        XS1_PORT_1I,
        XS1_PORT_1K,
        XS1_PORT_1L,
        XS1_CLKBLK_1
};

Multiple Heterogeneous SDRAM Support

It is possible for the application to drive multiple heterogeneous SDRAM devices simultaneously. In this case each sdram_server and sdram_ports usage must be explicit to the implementation. For example, to drive an IS42S16400F part and an IS42S16160D part, then the following will create the servers:

chan c,d;
par {
        sdram_server_PINOUT_V1_IS42S16400F(c, ports_0);
        sdram_server_PINOUT_V1_IS42S16160D(d, ports_1);
        app_0(c);
        app_1(d);
}

and the ports for the above would have been created by:

struct sdram_ports_PINOUT_V1_IS42S16400F ports_0 = {
        XS1_PORT_16A,
        XS1_PORT_1B,
        XS1_PORT_1G,
        XS1_PORT_1C,
        XS1_PORT_1F,
        XS1_CLKBLK_1
};
struct sdram_ports_PINOUT_V1_IS42S16160D ports_1 = {
        XS1_PORT_16B,
        XS1_PORT_1J,
        XS1_PORT_1I,
        XS1_PORT_1K,
        XS1_PORT_1L,
        XS1_CLKBLK_1
};

Notes

The sdram_server and application must be on the same tile.

Source code structure

Directory Structure

A typical SDRAM application will have at least three top level directories. The application will be contained in a directory starting with app_, the sdram module source is in the module_sdram directory and the directory module_xcommon contains files required to build the application.

app_[my_app_name]/
module_sdram/
module_xcommon/

Of course the application may use other modules which can also be directories at this level. Which modules are compiled into the application is controlled by the USED_MODULES define in the application Makefile.

Key Files

The following header file contains prototypes of all functions required to use use the SDRAM module. The API is described in :ref:`sec_api`.

Key Files

File	Description
sdram.h	SDRAM API header file

Module Usage

To use the SDRAM module first set up the directory structure as shown above. Create a file in the app folder called sdram_conf.h and into it insert a define for SDRAM_DEFAULT_IMPLEMENTATION. It should be defined as the implementation you want to use, for example for the Slicekit the following would be correct:

#define SDRAM_DEFAULT_IMPLEMENTATION PINOUT_V1_IS42S16160D

Declare the sdram_ports structure used by the sdram_server. This will look like:

struct sdram_ports sdram_ports = {
        XS1_PORT_16A,
        XS1_PORT_1B,
        XS1_PORT_1G,
        XS1_PORT_1C,
        XS1_PORT_1F,
        XS1_CLKBLK_1
};

Next create a main function with a par of both the sdram_server function and an application function, these will require a channel to connect them. For example:

int main() {
  chan sdram_c;
  par {
    sdram_server(sdram_c, sdram_ports);
    application(sdram_c);
  }
  return 0;
}

Now the application function is able to use the SDRAM server.

SDRAM Memory Mapper Programming Guide

The SDRAM memory mapper has a simple interface where to the mm_read_words and mm_write_words a virtual address is passes, this virtual address is mapped to a physical address and the I/O is performed there. The mm_wait_until_idle exists so that the application can run the I/O commands in a non-blocking manner then confirm that the command has when the mm_wait_until_idle returns.

Software Requirements

The component is built on xTIMEcomposer Tools version 12.0. The component can be used in version 12.0 or any higher version of xTIMEcomposer Tools.