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Monday, November 24, 2008

Dumb ATmega8 project, Open Flash Chart

Had some problems with reading in the tachometer output through a couple of external interrupt pins.  It seemed that every time the fan turned on, the "latency" light would turn on.  If it wasn't doing that, it the fan would turn off after a while.  I couldn't really figure out why it was doing this because the timers must have stopped working or the wireless sensor was being triggered automatically.  Eventually I found a remedy.  It was to increase the prescaler for the PWM timer.  I was using a prescale of 1 which may have been too fast and caused the interrupts to fight over each other.  I tried to get some meaningful output written to the 7-segment display but because of the distortion of the tachometer by the PWM, the numbers didn't really make sense.

I finally made changes to the Python library for Open Flash Chart.  Each graph variety class has its own "set" functions to properties that are fairly unique to other graphs.  This means you can change the properties after creating the graph dictionary.