def chip_select_active_low(active_low, chip=nil)
      chip = @chip if @chip
      chip = CHIP_SELECT_0 unless chip

      PiPiper.driver.spi_chip_select_polarity(chip, active_low ? 0 : 1)
    end
def chip_select_active_low(active_low, chip=nil)
      chip = @chip if @chip
      chip = CHIP_SELECT_0 unless chip

      PiPiper.driver.spi_chip_select_polarity(chip, active_low ? 0 : 1)
    end
Configure the active state of the chip select line

 The default state for most chips is active low.

 "active low" means the clock line is kept high during idle, and goes low when communicating.

 "active high" means the clock line is kept low during idle, and goes high when communicating.

 @param [Boolean] active_low true for active low, false for active high
 @param [optional, CHIP_SELECT_*] chip one of CHIP_SELECT_*