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Reset type

Asynchronous or synchronous reset logic for registers

Model Configuration Pane: Global Settings

Description

Specify whether to use asynchronous or synchronous reset logic when generating HDL code for registers.

Settings

Asynchronous (default) | Synchronous

Default: Asynchronous

Asynchronous

Use asynchronous reset logic. This reset logic samples the reset independent of the clock signal.

The following process block, generated by a Unit Delay block, illustrates the use of asynchronous resets. When the reset signal is asserted, the process block performs a reset, without checking for a clock event.

Unit_Delay1_process : PROCESS (clk, reset)
  BEGIN
    IF reset = '1' THEN
      Unit_Delay1_out1 <= (OTHERS => '0');
    ELSIF clk'event AND clk = '1' THEN
      IF clk_enable = '1' THEN
        Unit_Delay1_out1 <= signed(x_in);
      END IF;
    END IF; 
  END PROCESS Unit_Delay1_process;

Synchronous

Use synchronous reset logic. This reset logic samples the reset with respect to the clock signal.

The following process block, generated by a Unit Delay block, checks for a clock event, the rising edge, before performing a reset:

Unit_Delay1_process : PROCESS (clk)
  BEGIN
    IF rising_edge(clk) THEN
      IF reset = '1' THEN
        Unit_Delay1_out1 <= (OTHERS => '0');
      ELSIF clk_enable = '1' THEN
        Unit_Delay1_out1 <= signed(x_in);
      END IF;
    END IF; 
  END PROCESS Unit_Delay1_process;

Tips

To set this property, use the functions hdlset_param or makehdl. To view the property value, use the function hdlget_param.

For example, you can specify sync as the ResetType when you generate HDL code for the symmetric_fir subsystem inside the sfir_fixed model using either of these methods.

  • Pass the property as an argument to the makehdl function.

    makehdl('sfir_fixed/symmetric_fir', ... 
        'ResetType','async')

  • When you use hdlset_param, you can set the parameter on the model and then generate HDL code using makehdl.

    hdlset_param('sfir_fixed','ResetType','async')
makehdl('sfir_fixed/symmetric_fir')

Recommended Settings

No recommended settings.

Programmatic Use

Parameter: ResetType
Type: character vector
Value: 'async' | 'sync'
Default: 'async'

Version History

Introduced in R2012a

See Also