I have an array of 30 LEDs with 30 transistors driving them (one for each LED), with the base of each transistor being driven by output pins of an MCP23017 I/O expander (so that I can turn on/off each LED individually):
I want to add a master brightness control (i.e. one control for all of the LEDs), and my plan is to implement this using the PWM output of my microcontroller.
I want all of the "Enable" signals from the I/O expander to be strobed with the PWM signal (i.e. an AND between the PWM signal and the enable signals) - the MCP23017 does not have this functionality, so does anyone know of an I/O expander chip that can do this (i.e. has a "strobe" or "waveform" input that is ANDed with the output pin signals)? Or any alternative solutions?