Okay, since I dive a rEvo I should point out how the rEvo Dreams HUD works. It has three LEDs. When everything is groovy and your ppO2 is within the setpoint range you specified in the Dreams, it looks like this:
OOO
When the ppO2 starts to creep towards the low end it starts to look like this:
OOO
(Where the orange LED is blinking)
When the ppO2 starts to creep towards the high end it starts to look like this:
OOO
(Where the red LED is blinking)
In all three of these cases, the green LED is on and the gas is breathable and in the safe range. If the ppO2 gets below the safe range (or higher), then only the orange or red LED blinks. It doesn't give you the actual ppO2, but you know with good approximation where your ppO2 is based on the LED status.
Basically - blinking LEDs without any green LED is bad and you better adjust the mix in your loop. Any status with green LED on is within safe range, with only green being your target.
It works very well, but I do have to remind myself to look at it as the blinking is not annoying enough to catch my attention. But any CCR diver should be mindful of their ppO2 so you should be looking at it at regular intervals anyway.