Processing a 38khz IR signal - how much cpu is left ?

[FFMan]

I made a project a while ago using a BX24 to make a race laptimer for use in a race car. This detects a coded IR signal from the pit wall on each lap and displays the lap time etc in the car. This project had 2 parts, the BX24 to do the timing and control the display and user buttons, and a parallax SX processor to front end the IR decoding with a simple signal to the bx24 when the correct beacon was detected.

Now i'm a zx24 convert, i was planning a new version using a zx24. I wondered with the zx24s superior speed whether I could decode the 38khz signal and still have enough cpu cycles in between pulses to control the display of the lap time and race duration.

Is this achievable or will I still need a front end processor ?

[dkinzer]

[dlh]

Having done similar things (but with RF), I recommend using an n and interrupts. I would post my code but I lost it when a network HDD went south on me wiping out more than 2 months work.

The IR protocol will influence how much time you have.

[stevech]

[FFMan]

yes i'll use a Vishay ir module, so of course you are right. The three pulses which are the signature of this beam come over a duration of 4.65ms which in zx24 terms is an age considering not much code needs to run in the interim.

thanks

[stevech]

You can use, as a model/starting point for IR decode/encode, some of the projects on AVRfreaks.net's Projects section. One there is TWIRP.

[mikep]