This format is commonly referred to as 1.31 or Q31 format, where 1 is the number of bits used to represent the integer portion of the number, and 31 is the number of bits used to represent the fractional portion.

There may be a macro to do the Q15 to Q31 conversion, something like adc_q31 = IQ15toIQ31(adc_q15), check your IQmathLib.h header file. It can also be done with macros in two steps, as adc_q31 = IQtoIQ31(IQ15toIQ(adc_q15)), though this uses the 'global Q setting', which again could give you incorrect intermediate results if it's not set correctly.

Jan 15, 2020 · Signed Q31 is a fixed point format where you have 31 fractional bits, and can represent values from -1 to 2147483647/2147483648≃0.99999999953. Logical value v corresponds to 32-bit signed integer ⌈2147483648× v ⌋, and integer i …

Aug 13, 2019 · You're expect to pass an array with numbers in your selected fixed point format. Review the "data representation" expectations and diagrams. Values are going to need to be less than 1. If you have a 12-bit signed ADC value. q31 = adc12i << 20; q31 = (q31_t) (fltvalue * ( (float) (1 << 31))); Tips, Buy me a coffee, or three.. PayPal Venmo.

The Q15 data type can be represented by the 16-bit integer data type (short) and the Q31 data type can be represented by the 32-bit integer data type (int). These types are necessary when using the compiler's DSP built-in functions (see 29 Built-In Functions ).

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Feb 21, 2024 · Two remarks, not sure if they solve your problem: I use a more "direct" converion from float to q1_31, see below. The stdlib functions you call may induce substantial overhead since they all operate on true floats. Btw, if anyone recognizes a problem in this code, comments are welcome! I tried to get all the borderline cases right, but...

I am trying to understand what the clip_q63_to_q31 function (that's part of arm_math.h file) does. I initially thought it was to simply convert a Q63 number to a Q31 number, for example after multiplying two Q31 numbers this function would be called to converter the Q2.60 result to a Q31 number, but it appears to be doing something else.

using CMSIS arm_fir_init_q31 results in an extra 955,020B of ROM usage! I am working on a pretty simple data acquisition system based on a ATSAME70Q21B-CNT. I use DMA to ingest samples from an external SPI ADC, perform some FIR filtering, and FFT analysis and spit out the result over a cellular comm.

Apr 27, 2020 · I would like to understand whether using fixed point Q31 is better than floating-point (single precision) for DSP applications where accuracy is important. More details, I am currently working with ARM Cortex-M7 microcontroller and I need to perform FFT with high accuracy using CMSIS library.