●This manual provides all essential information you may need during the usage of this product.
●Please read this manual carefully before using this product and make sure that you are fully understand the contents of the manual.
●The product can only be maintained and repaired by qualified professionals, and only original spare parts are permitted to use for performance and safety reasons.
●This product DO NOT have polarity and over-voltage protection at all. Please wire and supply power according to the instructions.
●The working temperature of the product is from -10℃ to 60℃, please do not use it outside this temperature range to avoid risk and damage.
●The storage temperature of the product is from -20℃ to 75℃, please do not store it outside this temperature range to avoid risk and damage.
●For safety and performance, please DO NOT open the product casing or remove the IR-pass filter.
●Detecting object with high reflectivity, such as mirrors, smooth floor tiles, and calm milk liquid.
●Blocking the product with any transparent objects, such as water or glasses.
● The product’s lenses may be covered by dusts or dirt which may affect results, so please keep those lenses clean.
●The exposed circuit board is electrostatic sensitive. Please do not touch the circuit board of the product barehanded. Please use ESD wrist strap or antistatic gloves to ground yourself if any operation is necessary; Otherwise, the product may be damaged by static electricity.
TF-Luna is using Time of Flight (TOF) principle to measure distance, and it periodically emits near infrared modulated waves. TF-Luna calculates the time by measuring the phase difference between the original wave and the reflection wave and uses that time to get relative distance, as shown in Figure 1.
Figure 1: Schematics of TOF Principle
Table 1: Parameters specification of TF-Luna
|Accuracy||±6cm@ (0.2-3m) ②|
|Measurement unit||cm (Default)|
|Frame rate||1~250Hz ( adjustable ) ③|
① Operating range measured indoor based on a standard whiteboard with reflectivity 90% .
② This is theoretical, real value may be different.
③ 100Hz as default and only any factor (500/n, n can be any integer in [2, 500]) of 500Hz are available.
TF-Luna’s ranging accuracy is positively correlated with the strength value (amp) and negatively correlated with the output frame rate (frequency). The tables below show the standard deviation (STD) using 100Hz output rate. These values are for reference only, various testing environments may give different results.
Table 1 STD Amp correlation
Table 2 STD Dist correlation with 90% diffuse reflectance object
TF-Luna minimize the impact of external environment on ranging performance by optimizing light path and algorithm.
TF-Luna’s ranging dead zone is 20 cm or closer. Any distance output less than 20 cm is unreliable. The operating range of black and white targets are different:
The operating range of TF-Luna detecting black target with 10% reflectivity is 0.2-2.5m; The operating range of TF-Luna detecting white target with 90% reflectivity is 0.2-8m.
The ranging data are reliable only if the reflection surface fully covers the light spot, so the diameter of the object must at least the same as the diameter of the light spot, and that diameter depends on FOV of TF-Luna. The minimum diameter of the object surface has a formula:
d = 2 ∗ D ∙ tanβ
In the formula, d represents the minimum diameter, D is the distance of the object, and β is the half FOV of TF-Luna. Common values are shown in table 4 for your convenience:
Table4 Distance and minimum diameter
|Minimum diameter (d)||3.5cm||7cm||10.5cm||14cm||17.5cm||21cm||24.5cm||28cm|
If the light spot reaches two objects with different distances as Figure 2, the output distance value will be any value between the two actual distances of the objects, which may cause error for high-accuracy applications. Please try to avoid this situation for better accuracy and performance.
Figure 2 Detecting two objects at different location
Figure 3 TF-Luna appearance and size drawing
Table 5: Major Electrical Parameters of TF-Luna
|Power supply voltage||3.7V-5.2V|
|Communication signal level||LVTTL (3.3V)|
This product has no overvoltage nor polarity protection, so please make sure that the product is well connected, and the power supply voltage is inside the given range.
Figure 4 TF-Luna’s pin numbers
Table 6: The Function and Connection Description of each pin
|5||Configuration Input||Ground: I2C mode /3.3V: Serial port Communications mode|
|6||Multiplexing output||Default: on/off mode output I2C mode: Data availability signal on but not switching value mode|