Configure Emulation and Embedded Target Hardware

The Configuration Parameters dialog Hardware Implementation pane provides options that you can use to describe hardware properties, such as data size and byte ordering, and compiler behavior details that may vary with the compiler, such as integer rounding. The Hardware Implementation pane contains two subpanes:

• Embedded Hardware — Describes the embedded target hardware and the compiler that you will use with it. This information affects both simulation and code generation.

• Emulation Hardware — Describes the emulation target hardware and the compiler that you will use with it. This information affects only code generation.

The two subpanes provide identical options and value choices. By default, the Embedded Hardware subpane initially looks like this:

The default assumption is that the embedded target and emulation target are the same, so the Emulation Hardware subpane by default does not need to specify anything and contains only a checked option labeled None. Code generated under this configuration will be suitable for production use, or for testing in an environment identical to the production environment.

If you clear the check box, the Emulation Hardware subpane appears, initially showing the same values as the Embedded Hardware subpane. If you change any of these values, then generate code, the code will be able to execute in the environment specified by the Emulation Hardware subpane, but will behave as if it were executing in the environment specified by the Embedded Hardware subpane. See Configure Emulation Hardware Characteristics for details.

If you have used the Code Generation pane General tab to specify a System target file, and the target file specifies a default microprocessor and its hardware properties, the default and properties appear as initial values in the Hardware Implementation pane.

Options with only one possible value cannot be changed. Any option that has more than one possible value provides a list of legal values. If you specify any hardware properties manually, check carefully that their values are consistent with the system target file. Otherwise, the generated code may fail to compile or execute, or may execute but give incorrect results.

Note   Hardware Implementation pane options do not control hardware or compiler behavior. They describe hardware and compiler properties to MATLAB software, which uses the information to generate code for the platform thatruns as efficiently as possible, and gives bit-true agreement for the results of integer and fixed-point operations in simulation, production code, and test code.

The rest of this section describes the options in the Embedded Hardware and Emulation Hardware subpanes. Subsequent sections describe considerations that apply only to one or the other subpane. For more about Hardware Implementation options, see Hardware Implementation Pane. To see an example of Hardware Implementation pane capabilities, run the rtwdemo_targetsettings demo.

Identify theDevice Vendor

The Device vendor option gives the name of the device vendor. To set the option, select a vendor name from the Device vendor menu. Your selection of vendor will determine the available device values in the Device type list. If the desired vendor name does not appear in the menu, select Generic and then use the Device type option to further specify the device.

Note   For complete lists of Device vendor and Device type values, see Device vendor and Device type in the Simulink reference documentation. To add Device vendor and Device type values to the default set that is displayed on the Hardware Implementation pane, see Register Additional Device Vendor and Device Type Values.

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Identify the Device Type

The Device type option selects a hardware device among the supported devices listed for your Device vendor selection. To set the option, select a microprocessor name from the Device type menu. If the desired microprocessor does not appear in the menu, change the Device vendor to Generic.

If you specified the Device vendor as Generic, examine the listed device descriptions and select the device type that matches your hardware. If no available device type matches, select Custom.

If you select a device type for which the target file specifies default hardware properties, the properties appear as initial values in the subpane. Options with only one possible value cannot be changed. An option that has more than one possible value provides a list of legal values. Select values for your hardware. If the device type is Custom, all options can be set, and each option has a list of all possible values.

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Register Additional Device Vendor and Device Type Values

To add Device vendor and Device type values to the default set that is displayed on the Hardware Implementation pane, you can use a hardware device registration API provided by the Simulink Coder software.

To use this API, you create an sl_customization.m file, located in your MATLAB path, that invokes the registerTargetInfo function and fills in a hardware device registry entry with device information. The device information will be registered with Simulink software for each subsequent Simulink session. (To register your device information without restarting MATLAB, issue the MATLAB command sl_refresh_customizations.)

For example, the following sl_customization.m file adds device vendor MyDevVendor and device type MyDevType to the Simulink device lists.

function sl_customization(cm)
  cm.registerTargetInfo(@loc_register_device);
end

function thisDev = loc_register_device
  thisDev = RTW.HWDeviceRegistry;
  thisDev.Vendor = 'MyDevVendor';
  thisDev.Type = 'MyDevType';
  thisDev.Alias = {};
  thisDev.Platform = {'Prod', 'Target'};
  thisDev.setWordSizes([8 16 32 32 32]);
  thisDev.LargestAtomicInteger = 'Char';
  thisDev.LargestAtomicFloat = 'None';
  thisDev.Endianess = 'Unspecified';
  thisDev.IntDivRoundTo = 'Undefined';
  thisDev.ShiftRightIntArith = true;
  thisDev.setEnabled({'IntDivRoundTo'});
end

If you subsequently select the device in the Hardware Implementation pane, it is displayed as follows:

To register multiple devices, you can specify an array of RTW.HWDeviceRegistry objects in your sl_customization.m file. For example,

function sl_customization(cm)
  cm.registerTargetInfo(@loc_register_device);
end

function thisDev = loc_register_device

  thisDev(1) = RTW.HWDeviceRegistry;
  thisDev(1).Vendor = 'MyDevVendor';
  thisDev(1).Type = 'MyDevType1';
  ...

  thisDev(4) = RTW.HWDeviceRegistry;
  thisDev(4).Vendor = 'MyDevVendor';
  thisDev(4).Type = 'MyDevType4';
  ...

end

The following table lists the RTW.HWDeviceRegistry properties that you can specify in the registerTargetInfo function call in your sl_customization.m file.

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Set the Native Word Size for the Device

The Number of bits options describe the native word size of the microprocessor, and the bit lengths of char, short, int, and long data. For code generation to succeed:

• The bit lengths must be such that char <= short <= int <= long.

• All bit lengths must be multiples of 8, with a maximum of 32.

• The bit length for long data must not be less than 32.

Simulink Coder integer type names are defined in the file rtwtypes.h. The values that you provide must be consistent with the word sizes as defined in the compiler's limits.h header file. The following table lists the standard Simulink Coder integer type names and maps them to the corresponding Simulink names.

If no ANSI^® C type with a matching word size is available, but a larger ANSI C type is available, the Simulink Coder code generator uses the larger type for int8_T, uint8_T, int16_T, uint16_T, int32_T, and uint32_T.

An application can use integer data of any length from 1 (unsigned) or 2 (signed) bits up 32 bits. If the integer length matches the length of an available type, the Simulink Coder code generator uses that type. If no matching type is available, the code generator uses the smallest available type that can hold the data, generating code that never uses unnecessary higher-order bits. For example, on a target that provided 8-bit, 16-bit, and 32-bit integers, a signal specified as 24 bits would be implemented as an int32_T or uint32_T.

Code that uses emulated integer data is not maximally efficient, but can be useful during application development for emulating integer lengths that are available only on production hardware. The use of emulation does not affect the results of execution.

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Set the Byte Ordering Used By the Device

The Byte ordering option specifies whether the target hardware uses Big Endian (most significant byte first) or Little Endian (least significant byte first) byte ordering. If left as Unspecified, the Simulink Coder software generates code that determines the endianness of the target; this is the least efficient option.

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Set the Quotient Rounding Technique Used for Signed Integer Division

ANSI C does not completely define the quotient rounding technique to be used when dividing one signed integer by another, so the behavior is implementation-dependent. If both integers are positive, or both are negative, the quotient must round down. If either integer is positive and the other is negative, the quotient can round up or down.

The Signed integer division rounds to parameter tells the Simulink Coder code generator how the compiler rounds the result of signed integer division. Providing this information does not affect the operation of the compiler, it only describes that behavior to the code generator, which uses the information to optimize code generated for signed integer division. The parameter options are:

• Zero — If the quotient is between two integers, the compiler chooses the integer that is closer to zero as the result.

• Floor — If the quotient is between two integers, the compiler chooses the integer that is closer to negative infinity.

• Undefined — Choose this option if neither Zero nor Floor describes the compiler's behavior, or if that behavior is unknown.

The following table illustrates the compiler behavior that corresponds to each of these three options:

Note   Select Undefined only as a last resort. When the code generator does not know the signed integer division rounding behavior of the compiler, it generates extra code.

The compiler's implementation for signed integer division rounding can be obtained from the compiler documentation, or by experiment if no documentation is available.

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Set the Arithmetic Right Shift Behavior for Signed Integers

ANSI C does not define the behavior of right shifts on negative integers, so the behavior is implementation-dependent. The Shift right on a signed integer as arithmetic shift parameter tells the code generator how the compiler implements right shifts on negative integers. Providing this information does not affect the operation of the compiler, it only describes that behavior to the code generator, which uses the information to optimize the code generated for arithmetic right shifts.

Select the option if the C compiler implements a signed integer right shift as an arithmetic right shift, and clear the option otherwise. An arithmetic right shift fills bits vacated by the right shift with the value of the most significant bit, which indicates the sign of the number in twos complement notation. The option is selected by default. If your compiler handles right shifts as arithmetic shifts, this is the preferred setting.

• When the option is selected, the Simulink Coder software generates simple efficient code whenever the Simulink model performs arithmetic shifts on signed integers.

• When the option is cleared, the Simulink Coder software generates fully portable but less efficient code to implement right arithmetic shifts.

The compiler's implementation for arithmetic right shifts can be obtained from the compiler documentation, or by experiment if no documentation is available.

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Consider Platform Options for Development and Deployment

Configure Embedded Hardware Characteristics

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