04 Understanding the Parking Zones
Before moving on to the options and settings, it is important to understand how the application defines and uses 'parking zones'.
There are four parking zones defined as part of the parking process.
(Note: You can define the color used for each zone in the settings, but for simplicity, I'll be using 'green', 'yellow' and 'red' to describe the zones).
This is the zone farthest away from the sensor and final parking location. When the vehicle first enters the wake zone, the LEDs will wake up from standby/sleep mode and turn a solid color (green in my example). This lets the driver know the system is now active and tracking the vehicle's approach.
When the vehicle enters the active zone, the LEDs will switch to the active zone color (yellow) and begin applying the selected effect (e.g. LEDs begin to light up from the outside edges towards the center as the car gets closer to the parked zone). See below for some notes on setting the size of the active and parked zones. You can also see the currently available colors and effects in the Colors and Effects portion of this wiki.
As soon as the car enters the parked zone, all LEDs will turn solid (red here, but again, you specify the color). This is the desired final parked spot for the vehicle. Note that this should be a range, not an exact figure. See the notes below on active and parked zone sizes.
If the driver pulls too far forward and enters the backup zone, all LEDs will begin to flash rapidly, warning the driver that they should back up the vehicle. As soon as the vehicle leaves the backup zone and reenters the parked zone, the LEDs will quit flashing and again return to the parked zone solid color.
While your particular parking situation will somewhat dictate how you define your zone, here are some general thoughts and recommendations:
Active Zone: You initial inclination might be to make the active zone as large as possible so that the parking effects begin sooner. However, a larger active zone means less 'sensitivity' for each LED per distance traveled by the vehicle.
The application takes the size of the active zone (found by subtracting the starting distance of the parked zone from the starting distance of the active zone) and divides it by the total number of LEDs available for indicators based on the chosen effect (effects such as Out-In and In-Out only have 1/2 the number of LEDs since both ends of the LED strip are used) to calculate an 'interval distance' to show the next LED or set of LEDs per distance travled.
For example, if you have a total of 24 LEDs and have defined an active zone that is 96" deep. This means that a new LED will light up for each 4" traveled by the car. However, if the active zone depth is reduced to 48", a new LED will light up for every 2" traveled by the car. This greater sensitivity can be helpful as you approach the parked zone... especially if you have a narrow final parked zone.
The web settings page will let you experiment with distances of the zone before saving your settings, but you may decide that you don't want the active zone to begin until the vehicle has traveled about half of the distance between the wake zone and parked zone. Just remember, the smaller the active zone, the more 'sensitive' the LEDs will be when applying the active zone effect.
Parked Zone: You should try to make the parked zone as large as possible while still maintaining an adequate desired final parking location. While the TFMini sensor is pretty accurate, the driver parking the car may not be! The distance can be impacted by the angle, or left to right distance of the car in orientation to the sensor. This is most apparent if the front of the vehicle where the distance is being measured has some curve to it.
As shown in the example above, a car can be parked the exact same distance from the wall, but have different parked distance readings due to the curved front end. The car on the top has the front most portion of the car aligned with the sensor, while the car on the bottom has parked a little left of the sensor. This means if your parked zone begins at 16", the car on the bottom must pull forward another inch to reach the parked zone. For this reason, it is recommended that if your particular situation permits, you should make the parked zone size as wide as possible... a minimum of 6" is desirable if possible. To set a 6" parked zone, you will set the starting distance value of the parked zone 6" greater than the starting distance of the backup zone.
And a few final notes about zone distances. All distances in the web interface are entered in inches, but converted to millimeters for use by the application. They are then converted back to distances for web display. Due to limitations of the ESP8266 and floating point math, and due to rounding issues, it is possible that you can enter a decimal value for a distance (e.g 48.4") and when it is redisplayed the distanced displayed may change slightly (e.g. 48.3"), but the internal distance, in mm, doesn't change unless you update and save the actual value in the web interface.
The maximum distance allowable for any zone is 192" and the minimum is 12".