Programmable Potentiometer

This section details the use of functions specific to programmable potentiometer sub-units.

No potentiometer-specific functions are currently provided.

A potentiometer is represented logically as a programmable resistor (RES type) having twice the number of switched bits as its nominal resolution, i.e. a 24-bit potentiometer returns the type description RES(48). To make the unit behave correctly appropriate bit-patterns must be set in the upper and lower halves using general purpose output function pipx40_setChannelPattern. Transient effects must be expected when changing the wiper position; provided pipx40_MODE_NO_WAIT is not in force resistance values can only be transiently high.

Note that a potentiometer's state at power-up and when cleared is as a device of twice the nominal resistance with its wiper centred.

WARNING

Mis-programming can result in the potentiometer presenting a lower than normal resistance between its end terminals - in the worst case zero ohms.

Non-volatile (EEPROM) storage of calibration values is supported through the functions pipx40_readCalibration and pipx40_writeCalibration.