topic Re: loading an instant value to ftm.CNT counter value while counting in quadrature decoder mode in Kinetis Microcontrollers

loading an instant value to ftm.CNT counter value while counting in quadrature decoder mode

amerzater — Tue, 29 Oct 2019 10:15:11 GMT

I am using FTM2 on MKV10z32 as quadrateure decoder . and some times while running I re-synchronize the counter with a specific value and continue counting in the quadrature decoding mode from 0x0000 to 0xffff

I am using the next code to load the instant value(x) . but it seems that it dosnt work:

FTM2->SC=0x00;
FTM2->MOD=0xFFFF;
FTM2->CNTIN=x;
FTM2->CONTROLS[0].CnSC=0;
FTM2->CONTROLS[1].CnSC=0;
FTM2->QDCTRL|=0x01;
FTM2->MODE|=0x05;
FTM2->SC=0x48;
FTM2->CNTIN=0;

Re: loading an instant value to ftm.CNT counter value while counting in quadrature decoder mode

jingpan — Tue, 05 Nov 2019 02:35:10 GMT

Hi,

You code seems same as AN5142 quadrature encode example. Do you mean at first it can work correctly, but you can't write new value to FTM2->MOD or FTM2->CNTIN?

https://community.nxp.com/message/323855

QEI inputs, and index capture

Regards,

Jing

Re: loading an instant value to ftm.CNT counter value while counting in quadrature decoder mode

amerzater — Mon, 18 Nov 2019 11:41:03 GMT

the quadrature encoder works just fine after the first init. but when I need to load a new value to FTm->CNT during running. I do the next to load the new value by means of CNTIN

stop ftm clock
load new data to CNTIN and CNT regs
run ftm clock
reset CNTIN to allow counting from 0x0000 to FFFF

but it didnt work !!.

Re: loading an instant value to ftm.CNT counter value while counting in quadrature decoder mode

jingpan — Thu, 21 Nov 2019 06:29:50 GMT

Hi,

I made a demo to test how to update CNTIN and CNT. It use PTC1 and PTC2 to simulate quadrature input. You can see that any writing to CNT will make it reload CNTIN value.

Regards,

Jing