Preliminary test of optical flow sensor: gl9306

 

§01GL9306 Optical flow sensor

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One 、 Background introduction

   According to the national college student smart car competition ,  Intelligent vision group students ask ,  Whether optical flow sensor can be used GL9306.  In order to get familiar with the characteristics of this sensor ,  Bought a sensor on Taobao for testing .  Now let's test the characteristics of this sensor .

  

Two 、 Device characteristics

1、 Device interface

   The interface of the device is relatively simple ;  The three interface pins are defined as ： VDD、GND、 as well as UARG.  For serial port data output signal ,  The data communication format is given on the website page .  The baud rate of communication is 19200,  The frame rate of output data is 66H Group ,  The data represents the moving distance of the module .  When the distance is very small , Output is 0.
  

2、 Interface modification

   In order to test the module data on the bread board ,  Next, the module interface is transformed into 100mil Spacing joints .  Add heat shrinkable tubes after welding .  This is the sensor after the interface modification .

  

3、 ... and 、 Device test

1、 Power on and observe the interface signal

   Next, connect the sensor to the bread board ,  Apply 3.3V Working voltage of .  The steady-state working current of the device is about 20mA.  Use an oscilloscope to observe UART Output pin signal .  You can see that the pin has data output .  Specific data need to be discriminated by computer .  This is the period between each data frame ,  It's about 38ms,  The corresponding data frame rate is 26.3Hz.

  

2、 Reading data

   In order to read the output data of the optical flow sensor ,  It's used here MM32F3277 MicroPython Experiment board .  Use one of the UART（1）,  Occupied PA3(RXD),PA2(TXD),  The initialization baud rate is 19200,  Connect the module to the data output port of the optical flow sensor .

  
   Cycle read UART Received data , And show it .  This is the optical flow module sales website UART Data protocol .  The beginning and end of the data frame are 0xfe,0xaa.  In the middle is the data content .  This is the data internal structure given by the module website .  According to the data protocol , Write processing code .

  
   Here is MicroPython Code , Every 100ms Output the detected data .  It can be seen that when the optical flow sensor module moves , Output x,y Data changes .

  
 

※ real Test summary ※

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   this For optical flow sensor GL9306 A preliminary test was carried out . Its specific application needs to be further tested later .

  

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from machine                import Pin,UART
import time
uart = UART(1, baudrate=19200)
print(uart)
inbuf = bytes([0]*7)
recebuf = b''
mx = 0
my = 0
squal = 0
while True:
    if uart.any() > 0:
        inb = uart.read(uart.any())
        recebuf = recebuf + inb
    buflen = len(recebuf)
    delflag = 1
    if buflen > 0:
        id = 0
        for b in recebuf:
            if b == 254:
                if buflen >= id+9:
                    mx = recebuf[id+2]
                    mx = mx*256 + recebuf[id+1]
                    my = recebuf[id+4]
                    my = my*256 + recebuf[id+3]
                    squal = recebuf[id+6]
                else:
                    recebuf = recebuf[id:]
                    delflag = 0
                break
            id += 1
        if delflag > 0: recebuf = b''
    print(mx, my, squal)
    time.sleep_ms(100)