LPC MicrocontrollersのトピックRe: LPc11u67 Q-Math Functions

LPc11u67 Q-Math Functions

Hari_Royal — Sat, 22 Jul 2023 15:46:59 GMT

Hi,

I would like to implement one small control loop which requires using of Q format multiplication. I would like to know does LPC11U67 will support such Q21 format multiplication to implement below control loop.

Y (k) = 1.691 * Y (k−1) − 0.6913 * Y (k−2) + 2.116 * X( k−1 )− 1.91 * X (k−2)

Where k is a discrete time, X is the sensor value , Y is the output value of the controller.

I didn't found any DSP library supporting files in "LPCOpen 3.03 Keil Iar LPCXpresso 11U68" package. so some one help me is it possible to implement this control loop with #LPC11U67.

Re: LPc11u67 Q-Math Functions

xiangjun_rong — Mon, 24 Jul 2023 02:16:55 GMT

Hi,

I suppose this is a common problem for IIR filter that the absolute value of a1 may be greater than 1 and less than 2. With a transformation, you can use Q15 or Q31 format to implement it.

I attach the AN3359.pdf, pls refer to section 3.2.2 How to Implement the IIR Filter

Hope it can help you

XiangJun Rong

Re: LPc11u67 Q-Math Functions

frank_m — Mon, 24 Jul 2023 06:43:06 GMT

The DSP support files and libraries were supplied by ARM last time I checked.
Some vendors add them to their packages for convenience, but these DSP libs are not vendor-specific.

Like here : https://github.com/ARM-software/CMSIS-DSP

Re: LPc11u67 Q-Math Functions

xiangjun_rong — Tue, 25 Jul 2023 02:03:30 GMT

Hi,

You can use RTCESL tools to do IIR, you can download the library from the link:

https://www.nxp.com/design/software/embedded-software/real-time-control-embedded-software-motor-control-and-power-conversion-libraries:RTCESL

Hope it can help you

XiangJun Rong