This manual provides all the essential information during the usage of this product.
Please carefully read this manual and make sure that you fully understand everything herein.
The maintenance of this product should be done by the professional technician, and the product can only work with the factory spare part for ensuring the performance and safety.
This product itself has no polarity and over-voltage protection. Please properly connect and supply power as described in this manual.
Operating temperature of this product is between 0℃ and 60℃. Do not use it beyond this temperature range to prevent malfunction.
Storage temperature of this product is between -20℃ and 75℃. Do not store it beyond this temperature range to prevent malfunction.
For ensuring the product performance, do not open the product shell or remove the IR-pass filter.
Detecting object with high reflectivity, such as the mirror or the smooth floor tile, may cause a system malfunction.
The product will malfunction if there is any transparent object between it and the detecting object, such as glass or water.
The product will be subject to risk of failure if its transmitting or receiving len is covered by the dust. Please keep the lens clean.
Please do not directly touch circuit board of the product by hand as it is exposed. Please wear antistatic wrist strap or glove if necessary; Otherwise, the product will be subject to risk of failure, which is shown by failure of normal operation, and even it will be broken.
TFmini-S is an upgrade project based on TFmini. It is a miniaturized, single-point ranging product. Based on the TOF (time of flight) principle, it is designed with unique optics, electricity, and algorithms to achieve stability, precision, sensitivity and high-speed distance measurement function.
In addition to the low-cost, small-size, and long-ranging of the TFmini, the product itself has higher distance measurement accuracy. It is more adaptable to different outdoor environments such as strong light, different temperatures, and different reflectances. It has lower power consumption and more flexible detection frequency. The product is compatible with both the UART and I2C interface. Different interfaces can be switched by commands.
TFmini-S is based on TOF (Time of Flight). To be specific, the product emits modulation wave of near infrared ray on a periodic basis, which will be reflected after contacting object. The product obtains the time of flight by measuring round-trip phase difference and then calculates relative range between the product and the detection object, as shown in Figure 1.
Figure 1 Schematics of TOF Principle
Table 1 Main Characteristic Parameters of TFmini-S
① Operating range based on a standard whiteboard with 90% reflectivity in indoor condition
② The distance measurement here is absolute accuracy, and the specific repeat accuracy will be described in section 2.4.
③ 2°is the theoretical value, from which the actual value will be different.
④ Only frame rates meeting the formula–1000/n (n is positive integer) can be set. The default frame rate is 100Hz.
The repeat accuracy of TFmini-S is directly related to the Strength value measured and the output frame rate (Frequence). The ranging repeat accuracy is characterized by the standard deviation of ranging. When the frame rate is 100 Hz, the standard deviation of ranging is as follows under the background of 90% transmittance:
Table 2 Statistics: the standard deviation of TFmini-S at 100Hz and 90% reflectivity
With optimization of light path and algorithm, TFmini-S has minimized influence from external environment on distance measurement performance. Despite that, the range of distance measurement may still be affected by the environment illumination intensity and the reflectivity of detection object. The detection blind zone of TFmini-S, 0-10cm, within which the output data is unreliable.
The operating range of TFmini-S detecting black target with 10% reflectivity, 0.1-5m. The operating range of TFmini-S detecting white target with 90% reflectivity, 0.1-12m.
The diameter of light spot depends on the FOV of TFmini-S (the term of FOV generally refers to the smaller value between the receiving angle and the transmitting angle), which is calculated as follows:
d = 2 ∗ D ∙ tanβ
In the formula above, d is the diameter of light spot; D is detecting range; β is the the value of the half receiving angle of TFmini-S, 1°. Correspondence between the diameter of light spot and detecting range is given in Table 3.
Table 3 the Minimum side length of effective detection corresponding to Detecting Range
|Minimum side length||3.5cm||7cm||10.5cm||14cm||17.5cm||21cm||24.5cm||28cm||31.5cm||35cm||38.5cm||42cm|
If the light spot reaches two objects with different distances, as shown in Figure 2, the output distance value will be a value between the actual distance values of the two objects. For a high accuracy requirement in practice, the above situation should be noticed to avoid the measurement error.
Figure 2 Distance Measurement in the case of Two Objects of Different Distances
Figure 3: Dimension of TFmini-S(Unit:mm)
Table 4: Major Electrical Parameters of TFmini-S
This product has no overvoltage nor polarity protection, so please make sure that connection and power supply are normal. The fluctuation of the power supply voltage in a range of ±0.1V is allowable.
Average current varies along with the operating modes of the product in two patterns, more specifically, its current is around 50mA under short distance mode and it is around 140mA under long distance mode.
Table5: The Function and Connection Description of each pin
Type of connecting terminal: GH1.25-4P. The product includes a 10cm long connecting wire, the other end of which is a conventional 1.25-4p terminal (Molex510210400). The user may extend this wire as he/she needs. In order to ensure effective data transmission, it is recommended that the length of the connecting wire welded by the user should be less than 1m.
TFmini-S adopts the serial port data communication protocol, as given in Table 6.
Table 6 Data Communication Protocol of TFmini-S——UART
|Default baud rate||115200|