CMSIS Conditions for DSP Blocks to Support ARM Cortex Processors

DSP blocks that can be used with the Support Package for ARM^® Cortex^®-M processors require specific conditions to allow code replacement with the CMSIS Library. You use this code replacement when generating C code from a model. The support package do not support any multi-rate DSP blocks in the ARM CRL library. The CMSIS library supports these DSP blocks only when you set specific properties, as indicated in the following table:

Note

In the Fixed-point mode of the CMSIS DSP functions (FIR and Biquad filters), Wrap is used for intermediate MAC operations if accumulator result overflows. At the end, the accumulator is right shifted and saturated to the output data type. For discrete FIR and Biquad filter blocks, there is only one overflow setting for accumulator and output. So if overflow happens in accumulation, the simulation result will not match the CMSIS library result. If Overflow Mode is set to 'Wrap' or SaturateOn IntegerOverflow is turned off and only the output overflows, the simulation result will also not match the CMSIS library result.

DSP Block	Input Requirements	Parameter Requirements	Equivalent CMSIS Functions
Discrete FIR Filter	Real values. Output must also be real values. `single` data type for `Lattice MA` structure. `single` or fixed-point data types for `Direct Form` structure. For fixed-point data, the input word length: For word length 8,supported fractional bits is 7 For word length 16,supported fractional bits is 15 For word length 32,supported fractional bits is 31 , but the input and output must be the same data type. Single channel (one column).	Filter structure: `Direct Form` or `Lattice MA`. Input processing: `Columns as channels (frame based)`. Initial states: `0`. Coefficients source: `Dialog parameters` or `Input port`. For fixed-point Discrete FIR Filter block with `Direct Form Structure`: Rounding mode:`'Floor'`. Saturate on integer overflow: On (check box is selected) or Off (check box is cleared). LockScale: `On`. Fixed-Point Property Settings for Discrete FIR Filter Block Q15-specific: Number of filter coefficients must be even and greater than or equal to 4. If not, pad zeros at the end.	`'Direct Form'` Structure: `arm_fir_f32` `arm_fir_init_f32` Fixed-point input with Q7 format: `arm_fir_q7` `arm_fir_init_q7` Fixed-point input with Q15 format: `arm_fir_q15` `arm_fir_init_q15` Fixed-point input with Q31 format: `arm_fir_q31` `arm_fir_init_q31` `'Lattice MA'` Structure: `arm_fir_lattice_f32` `arm_fir_lattice_init_f32`
FIR Decimation	Real values. Output must also be real values. `single` data type. Single channel (one column).	Coefficients source: `Dialog parameters`. Filter structure: `Direct Form` Input processing: `Columns as channels (frame-based)`. Rate options: `Enforce single-rate processing`. Allow arbitrary frame length for fixed-size input signals: Clear the parameter.	`arm_fir_decimate_init_f32` `arm_fir_decimate_f32`
FIR Interpolation	Real values. Output must also be real values. `single` data type. Single channel (one column).	Coefficients source: `Dialog parameters`. Input processing :`Columns as channels (frame based)`. Rate options: `Enforce single-rate processing`.	`arm_fir_interpolate_init_f32` `arm_fir_interpolate_f32`
LMS Filter	Real values. Output must also be real values. `single` data type. Single channel.	Specify step size via: `Dialog` (mu specified from the dialog). Reset port:`None`. Output filter weights : `off` (no weights output port). Adapt port : `off` (no adapt output port). Leakage: 1. Initial value of filter weights: `0`. Algorithm: `LMS` or `Normalized LMS`.	`arm_lms_init_f32` `arm_lms_f32` If the algorithm is `Normalized LMS`: `arm_lms_norm_f32` `arm_lms_norm_init_f32`
Biquad Filter	Real values. Output must also be real values. `single` or fixed-point data type. For fixed-point data, the input word length: For word length 16,supported fractional bits is 15 For word length 32,supported fractional bits is 31 , but the input and output must be the same data type. Single channel (one column). Single rate mode.	Coefficients source: `Dialog parameters` or `Input port(s)`. Restriction: If Coefficient source is `Input port(s)`, replacement only occurs when Scale value mode is set to `Assume all are unity and optimize`. Filter structure: `Direct Form I` or `Direct Form II transposed`. Initial conditions: `0`. Input processing: `Columns as channels (frame based)`. For fixed-point support for `Direct Form I Structure` for Q15, Q31, and Q15 fast version: Rounding mode:`'Floor'`. Overflow mode: `Wrap` or `Saturate`. Lock data type settings: `On`. Fixed-Point Property Settings for Biquad Filter Block	`arm_biquad_cascade_df1_init_f32` `arm_biquad_cascade_df2T_init_f32` `arm_biquad_cascade_df1_f32` `arm_biquad_cascade_df2T_f32` `arm_biquad_cascade_df1_init_q15` `arm_biquad_cascade_df1_q15` `arm_biquad_cascade_df1_fast_q15` `arm_biquad_cascade_df1_init_q31` `arm_biquad_cascade_df1_q31`
FFT	Complex values. `single` data type. Single channel. Input length must equal FFT length.	FFT implementation: `Radix-2`. Scale result by FFT length: Off (check box is cleared). Inherit FFT length from input dimensions: Off (check box is cleared). FFT length:`16, 64, 256, 1024`	`arm_cfft_radix2_init_f32` `arm_cfft_radix2_f32`
IFFT	Complex values. `single` data type. Single channel. Input length must equal FFT length.	FFT implementation: `Radix-2`. Divide output by FFT length: On (check box is selected). Inherit FFT length from input dimensions: Off (check box is cleared). FFT length:`16, 64, 256, 1024`	`arm_cfft_radix2_init_f32` `arm_cfft_radix2_f32`
Correlation Convolution	Real values. Output must also be real values. `single` data type. Single channel. The two inputs must be the same length.	Computation domain: `Time`.	`arm_conv_f32` `arm_correlate_f32` There are no `init` functions associated with these algorithms.
Mean RMS Variance Standard deviation	Non-scalar, real values. Output must also be real values. `single` data type. Single channel, one-dimensional. The two inputs must be the same length.	Running statistic : Off (check box is cleared). Enable ROI Processing: Off (check box is cleared). ROI does not apply to RMS. Find statistic over: `entire input`.	`arm_mean_f32` `arm_rms_f32` `arm_var_f32` `arm_std_f32` There are no `init` functions associated with these algorithms.