LPC21xx/Timer

The LPC21xxes has two 4-channel timers. However, one channel of one timer is not connected to external pins so can only be used to generate interrupts.

Apart from the one not connected to the outside world, each timer channel can be used to counte external events, generate a signal at a chosen frequency, or to trigger an internal interrupt after a given time interval or a given number of external events.

Somebody had an [adventure] with a race condition concerning the timer - disabling it in the same clock tick as it tries to trigger the external output can result in asynchronous behaviour!

The LPC21xx/PWM? outputs are based on a variation of the timer circuits.