calculate_max_brightness_for_power_mW() [2/2]

uint8_t calculate_max_brightness_for_power_mW	(	uint8_t	target_brightness,
		uint32_t	max_power_mW )

Determines the highest brightness level you can use and still stay under the specified power budget for all sets of LEDs.

Unlike the other internal power functions which use a pointer to a specific set of LED data, this function uses the CFastLED linked list of LED controllers and their attached data.

Parameters

target_brightness	the brightness you'd ideally like to use
max_power_mW	the max power draw desired, in milliwatts

Returns

a limited brightness value. No higher than the target brightness, but may be lower depending on the power limit.

Definition at line 111 of file power_mgt.cpp.

{
    uint32_t total_mW = gMCU_mW;
 
    CLEDController *pCur = CLEDController::head();
    while(pCur) {
        total_mW += calculate_unscaled_power_mW( pCur->leds(), pCur->size());
        pCur = pCur->next();
    }
 
#if POWER_DEBUG_PRINT == 1
    Serial.print("power demand at full brightness mW = ");
    Serial.println( total_mW);
#endif
 
    uint32_t requested_power_mW = ((uint32_t)total_mW * target_brightness) / 256;
#if POWER_DEBUG_PRINT == 1
    if( target_brightness != 255 ) {
        Serial.print("power demand at scaled brightness mW = ");
        Serial.println( requested_power_mW);
    }
    Serial.print("power limit mW = ");
    Serial.println( max_power_mW);
#endif
 
    if( requested_power_mW < max_power_mW) {
#if POWER_LED > 0
        if( gMaxPowerIndicatorLEDPinNumber ) {
            Pin(gMaxPowerIndicatorLEDPinNumber).lo(); // turn the LED off
        }
#endif
#if POWER_DEBUG_PRINT == 1
        Serial.print("demand is under the limit");
#endif
        return target_brightness;
    }
 
    uint8_t recommended_brightness = (uint32_t)((uint8_t)(target_brightness) * (uint32_t)(max_power_mW)) / ((uint32_t)(requested_power_mW));
#if POWER_DEBUG_PRINT == 1
    Serial.print("recommended brightness # = ");
    Serial.println( recommended_brightness);
 
    uint32_t resultant_power_mW = (total_mW * recommended_brightness) / 256;
    Serial.print("resultant power demand mW = ");
    Serial.println( resultant_power_mW);
 
    Serial.println();
#endif
 
#if POWER_LED > 0
    if( gMaxPowerIndicatorLEDPinNumber ) {
        Pin(gMaxPowerIndicatorLEDPinNumber).hi(); // turn the LED on
    }
#endif
 
    return recommended_brightness;
}

References calculate_unscaled_power_mW(), gMaxPowerIndicatorLEDPinNumber, gMCU_mW, CLEDController::head(), Pin::hi(), CLEDController::leds(), Pin::lo(), CLEDController::next(), and CLEDController::size().

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