input capture , impulse measurment

[juliend1985]

Posted on April 25, 2006 at 09:38

input capture , impulse measurment

[juliend1985]

Posted on April 25, 2006 at 09:09

Hello,

I have a numerical signal(composed of pulse of 1 and 0 logical) which arrives on the entry of the input capture of the microcontrolor st7lite It is necessary that I count the duration of the impulses which are in a high state (1)

Extracts of datasheet are attached.

I want to know how to measure one impulsion time with register LTICR(Life Time Input Capture Register)

it is said in datasheet that we use a counter (counter 1) which counts from 0 to 255 , ther is a ltic pin which enquiries if there is a detection of a high level on the numerical signal

icf flag set (1) then register LTICSR1 is containing MSB of the counter 1.But I don't understand how msb counter 1 indicates us duration of the pulse.

How i Can do to know duration of the pulse with datasheet?

http://shaka19free.fr/fdf/portail/upload/images/shemainputcapture.JPG

http://shaka19free.fr/fdf/portail/upload/images/counter1.JPG

http://shaka19free.fr/fdf/portail/upload/images/inputcapturetxt.JPG

________________

Attachments :

counter1.JPG : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006I0EP&d=%2Fa%2F0X0000000bVo%2Ft0vVfikcVfdz5iBPSwcCUoTVKuXWhV0JWQa2JRHK1iI&asPdf=false

inputcapturetxt.JPG : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006I0EK&d=%2Fa%2F0X0000000bVm%2FojstAhLeX5YYC_A5MsrwjGGelpOzp.nGCDkMLsV6e.M&asPdf=false

shemainputcapture.JPG : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006I0EF&d=%2Fa%2F0X0000000bVn%2F15YTmbJLi0GVBJ.zAgn9IJjumnfFaKgSnLtZnVQRob4&asPdf=false

[laurent239955_stm1]

Posted on April 25, 2006 at 09:38

Hi,

There is Application Note AN1324 available on ST web site which can help you. The method use to calibrate the RC is to measure a pulse with a known duration (50hz signal) using the input capture.

This application is also available for the ST7Ultralite AN2326.

Best regards

Laurent