====== StepAccel ======

Output an accelerated, finite pulse train on the specified ''pin'' using a PIO state machine.

===== Syntax =====

<code python>
from cubloc import StepAccel

StepAccel(
    pin: int,
    freqBase: int,
    freqTop: int,
    freqAccel: int,
    qty: int)
</code>

===== Parameters =====

  * **pin**: Output GPIO pin number.
  * **freqBase**: Starting pulse frequency in pulses per second.
  * **freqTop**: Final pulse frequency after acceleration.
  * **freqAccel**: Acceleration rate in pulses per second per second. Must be > 0 when ''freqBase'' < ''freqTop''.
  * **qty**: Number of pulses to output.

===== Exceptions =====

  * [[https://docs.micropython.org/en/latest/library/builtins.html#TypeError|TypeError]]: An argument has an invalid type.
  * [[https://docs.micropython.org/en/latest/library/builtins.html#ValueError|ValueError]]: ''channel'' or a numeric argument is outside the supported range.

===== Notes =====

  * Note: Acceleration is implemented as a staircase of fixed-frequency PIO segments, so small gaps can occur when the next segment is reconfigured.

===== Example =====

<code python>
from cubloc import StepAccel

StepAccel(15, 1000, 5000, 2000, 50000)

while True:
    pass
</code>

===== Related APIs =====

  * [[logicpython:cubloc_api:steppulse|StepPulse]]
  * [[logicpython:cubloc_api:stepstat|StepStat]]
  * [[logicpython:cubloc_api:stepstop|StepStop]]