Content originally posted in LPCWare by karpis on Tue Mar 22 05:31:59 MST 2016
Hello everybody,
I using LPC1549 100 pin MCU and trying to decide the best way to measure fan RPM. Fan has simple feedback with square impulse for rotation.
Now I'm in doubt should I use :
1. RIT with GPIO interrupt. On rising edge on GPIO it would generate interrupt and increment rpm_count value. Then RIT periodically counts by known formula actual RPM and resets rmp_count value on its own interrupt.
2. SCT. I would assign input to SCT_IN, event on SCT_IN rising edge and event on count down. On rising edge event I would increment rpm_count value and on count down I would use formula, reset rpm_count and restart SCT timer. I still have not found yet if it is possible to increment rpm counter without interrupts - that would be a huge improvement on 1st choice, which will load MCU with interrupts.
Has anyone did this before and how did you do it?
