sr04 ultra sonic

[stan cartwright]

Hi all. I want to finish some robot projects and dug out hsr04 ultrasonic rangefinders and code.
The code I used for a working robot vehicle used include sr04 and not sure how it works.
I noticed all my sr04 units I've soldered a 2.2k resistor between echo and trig and use just trig to one port.
The gcb sr04 include sends a ping by turning a port on,wait 10 us,turn pot off,then I don't know.
I found this link about sr04 and the method is bit different and range is different conversion value.
https://www.mpja.com/download/hc-sr04_ultrasonic_module_user_guidejohn.pdf last page.
Some code I'l try. Any thoughts?

#define ultra portb.0
dim temp as byte
dim range as word

dir ultra out
for temp = 1 to 8
  set ultra on
  wait 25 us
  set ultra off
  wait 25 us
next
dir ultra in
pulsein ultra,range,us
range=range/58 ;cm

[Anobium]

The GCB SR04 library works. It is sends a ping and wait for a ping. If supports many devices.

I do not think I posted any demos as it is very simple to use.

  #chip 16f1939,32
  #config MCLRE_ON, PLLEN_ON,
  #include <srf04.h>

  #include <glcd.h>
  #define GLCD_TYPE GLCD_TYPE_KS0108               ' This is the Default value, not required.


  #define GLCDDirection 1

   #define GLCD_CS1 PORTC.1    'D12 to actually since CS1, CS2 can be reversed on some devices
   #define GLCD_CS2 PORTC.0
   #define GLCD_DB0 PORTD.0 'D0 to pin 7 on LCD
   #define GLCD_DB1 PORTD.1 'D1 to pin 8 on LCD
   #define GLCD_DB2 PORTD.2 'D2 to pin 9 on LCD
   #define GLCD_DB3 PORTD.3 'D3 to pin 10 on LCD
   #define GLCD_DB4 PORTD.4 'D4 to pin 11 on LCD
   #define GLCD_DB5 PORTD.5 'D5 to pin 12 on LCD
   #define GLCD_DB6 PORTD.6 'D6 to pin 13 on LCD
   #define GLCD_DB7 PORTD.7 'D7 to pin 14 on LCD

   #define GLCD_RS PORTe.0
   #define GLCD_Enable PORTe.2
   #define GLCD_RW PORTe.1
   #define GLCD_RESET PORTC.2

   ' Timing for 32 mhz
   #define KS0108ReadDelay    6
   #define KS0108WriteDelay   0
   #define KS0108ClockDelay   0


; ----- Constants

    #define US1Ping PORTC.7
    #define US1Echo PORTC.6

    #define AlarmDistance 50

; ----- Variables
    Dim Distance As word

; ----- Main body of program commences here.

    GLCDCLS
    glcdprint 0,   0, "GCBasic 2016"
    glcdprint 0,   8, "SRF04 Demo"
    wait 2 s

    Do Forever


              'Take a distance reading from the SRF04
              Distance = USDistance(1)

              'Check the reading, is the object too close to the SRF04?
              if Distance < AlarmDistance then
                        GLCDPrint ( 0, 24, "Close" )
                        GLCDPrint (0, 32 , str(Distance)+"  " )
              Else
                        GLCDPrint ( 0, 24, "Far  " )
                        GLCDPrint (0, 32 , "     " )
              end if

              'Delay for a few milliseconds before taking the next reading
              Wait 10 ms
    Loop


end

[Anobium]

another demo,

  #chip 16f1939,32
  #config Osc = INT, VCAPEN_OFF, MCLRE_On, PLLEN_ON, CLKOUTEN_OFF, WDTE_SWDTEN
  ;Include files (Libraries)
  #include <srf04.h>



; ----- Constants

    #define LED1 PORTD.1
    #define LED2 PORTD.2
    #define LED3 PORTD.3
    #define LED4 PORTD.4
    #define LED5 PORTD.5

    #define US1Ping PORTC.7
    #define US1Echo PORTC.6
    #define AlarmDistance 50

    '7 segment
    #define DISP_SEG_A PORTB.0
    #define DISP_SEG_B PORTB.1
    #define DISP_SEG_C PORTB.2
    #define DISP_SEG_D PORTB.3
    #define DISP_SEG_E PORTB.4
    #define DISP_SEG_F PORTB.5
    #define DISP_SEG_G PORTB.6

    #define DISP_SEL_1 PORTA.0
    #define DISP_SEL_2 PORTA.1


; ----- Variables
    Dim Distance As word

; ----- Main body of program commences here.

    Do Forever

              'Take a distance reading from the SRF04
              Distance = USDistance(1)

              'Check the reading, is the object too close to the SRF04?
              if Distance < AlarmDistance then
                  Select Case Distance

                    case < 10
                      SetWith ( led1, 1 )
                      SetWith ( led2, 0 )
                      SetWith ( led3, 0 )
                      SetWith ( led4, 0 )
                      SetWith ( led5, 0 )

                    case < 20
                      SetWith ( led1, 1 )
                      SetWith ( led2, 1 )
                      SetWith ( led3, 0 )
                      SetWith ( led4, 0 )
                      SetWith ( led5, 0 )

                    case < 30
                      SetWith ( led1, 1 )
                      SetWith ( led2, 1 )
                      SetWith ( led3, 1 )
                      SetWith ( led4, 0 )
                      SetWith ( led5, 0 )
                    case < 40
                      SetWith ( led1, 1 )
                      SetWith ( led2, 1 )
                      SetWith ( led3, 1 )
                      SetWith ( led4, 1 )
                      SetWith ( led5, 0 )
                    case < 50
                      SetWith ( led1, 1 )
                      SetWith ( led2, 1 )
                      SetWith ( led3, 1 )
                      SetWith ( led4, 1 )
                      SetWith ( led5, 1 )

                    case else

                      SetWith ( led1, 0 )
                      SetWith ( led2, 0 )
                      SetWith ( led3, 0 )
                      SetWith ( led4, 0 )
                      SetWith ( led5, 0 )

                  End Select

                  '7 Segment here

                  'Get the 2 digits
                  Number = Distance
                  Num1 = 0
                  If Number >= 10 Then
                      Num1 = Number / 10
                      'SysCalcTempX stores remainder after division
                      Number = SysCalcTempX
                  End If
                  Num2 = Number

                  'Show the digits
                  'Each DisplayValue will erase the other (multiplexing)
                  'So they must be called often enough that the flickering
                  'cannot be seen.
                  Repeat 100
                      DisplayValue DISP_SEL_1, Num1
                      Wait 1 ms
                      DisplayValue DISP_SEL_2, Num2
                      Wait 1 ms
                  End Repeat

              end if

              'Delay for a few milliseconds before taking the next reading
              Wait 10 ms
    Loop


end

[Anobium]

and, look at the demo folders .... I did post demos.

https://github.com/Anobium/Great-Cow-BASIC-Demonstration-Sources/tree/master/UltraSonic_Sensor_Solutions

[stan cartwright]

Thanks. There were demos. The ping is one pulse that makes the device oscillate or "ring" for a few cycles at it's resonant frequency but that wasn't explained in the link I posted.
4 pin devices are more common but if you connect echo and trig via 2K2 resistor you just use the trig pin and the 3 pin sro4 device option. You save a port.

[Anobium]

Are you asking? or, telling us?

[stan cartwright]

The link I posted and others, make it seem you need a 40KHz signal to drive the sr04. It says "8 pulses at 40KHz"... not so as I found with more searching.
I also found the devices work better upright than horizontal as there's an offset to near objects ie not at a right angle to sr04.