I was playing with interfacing pressure/temp sensor on SPI with Arduino Uno 328. This initially worked well and very stable with 2 different sensors. Then ,after disconecting and rebooting, I started to get completely random readings. I noticed the LED attached to pin 13 changed behaviour - when the sensor was working OK the LED was rapidly and constantly blinking . Now it blinks for a short time every 6 seconds- and when it blinks I get the SPI reading (a false one). I believe the SCLK is somehow broken - any ideas ? Have I changed some fuse bit, that broke the SCLK timing? What should I do ? - Burn the bootloader ?
Burning a fresh bootloader will reset all the fuses.