Lpc2000

--- In lpc2000@yahoogroups.com, "chazeltopman" <rob@n...> wrote:
> 
> Well, I went and built some tools to help me solve some problems and
> this is what I found with what I built.
> 
> Architecturally, I merged two state machines into one so that they
> can run sequentially to reduce contention.  Also since there is only
> one interrupt vector (TIMER1), it maps better to a single state
> machine.  The states from the Left-Right state machine and the
> Fore-Aft state machine now combine to become the 2D-TILTS state
> machine.  This also makes it easier to coordinate common states like
> powerup, idle and powerdown.  The tilt sensor states are (in
> IsoMax):
> 
> MACHINE 2D-TILTS  \ capture and measure tilt signals
>   APPEND-STATE LR-SYNCING  \ find a rising edge on first signal
>   APPEND-STATE LR-RISING   \ record a rising edge
>   APPEND-STATE LR-FALLING  \ record pulse length
>   APPEND-STATE LR-PERIOD   \ record period length
>   APPEND-STATE FA-SYNCING  \ repeat for other signal
>   APPEND-STATE FA-RISING
>   APPEND-STATE FA-FALLING
>   APPEND-STATE FA-PERIOD
>   APPEND-STATE TILT-OFF    \ no measurements; can be powered off
> 
> The syncing state waits for a rising edge and then discards the
> reading.  The rising and falling states record and subtract the
> times to get the pulse width and then the period state takes a final
> rising edge measurement to gauge the period for that pulse.  One
> signal is dealt with, then the other, changing edge triggers each
> state in TIMER1_CCR always writing zero in between.  This worked
> quite well and I could trigger a reading when needed except
> sometimes the pulse and period would be one period longer.  I
> cleaned up the glitch by using the previous period and modulus but
> that got me to digging for the source of the glitch.
> 
> There are a total of 6 interrupts running on the the 2106, 4
> synchronously, 2 asynchronously.  I used the TIMER_TC to time how
> long it takes to service each interrupt and then keep the maximum
> time value.  Then I view these values to see how long the interrupts
> were taking.  It turns out that occasionally, one interrupt,
> TILT-VIEWER which did LCD graphing was taking 1.5ms, which was
> longer than the LR or FA periods (1ms).  So I refactored the looping
> code from inside one state into multiple states which displayed the
> current value, and then graphed the historical value, for both
> signals sequentially and synchronously.  The tilt viewer state are
> (in IsoMax):

[deleted]

It looks like you are working with the ADXL202 accelerometer. I'm 
using one with an AVR for my initial prototype, but will be moving to 
an MSP430 later.

Leon