simple tachometer
Hi,
Hope you don't mind me joining the party here, but I've been asked to do a similar thing, with one small exception. The 'output' is simply an indicator, LED, that starts to flash at a predetermined rpm, then flashes faster, and finally is continually when another rpm is reached.
Now, it would be good practice for me to use 'logic' or timers, but I might as well just use a small PIC, as IanP suggested. They all come with at least one timier, so it won't have to be a flagship PIC or anything.
However, although I think I can sort out measuring the rpm from the engine (depends on where it getting timing from, ECU or sparks/sensors) using a timer, I'm not sure where to being for the flashing LED. Say I had the lower limit as 3000rpm, and the upper as 5000. I would like this to be used entirely for the 3000-5000 range. Would anyone recommend 'waiting' a set time, before starting timing? eg, wait 12ms, then start a timer so I don't waste the resolution of it for speeds of >5000.
I must say, although I've been using PIC's for a while, I'm a tad indicisive about using a 'counter' or a 'timer' (or both). IanP or anyone else, please advise.
Thankyou,
BuriedCode.