that sound,noise and beep

[stan cartwright]

How to make that "noise" sshhh sound lorries and emergengy vehicles make without a mp3 player.
I want to make others aware of me on a bicycle other than a bell becuse they would use a bell if better. noise is omni-directional
It's turning a port on off through an amp. I looked for the sound to sample. It's late. Any thoughts other than mp3 player?
more a squelch sound https://www.youtube.com/watch?v=fa28lIGuxq8
If I can find the sound then use audacity and how much mem needed and how. Not random port on off which works sort of. Daft idea. Ride a bike.

[Chris Roper]

This should point you in the right direction:

;
;   Pseudorandom digital white noise generator for PIC series.
;
;   PIC12C508 version written April 7th, 1997 by Scott Rider.
; Questions/comment to chip@aeug.org
;
;   This program uses Microchip assembler mnemonics and the Microchip
; MPASM assembler (http://www.microchip.com/).  Default config options
; are set in the __FUSES line below: MCLRE off, CP off, WDT off, OSC=INTRC.
;
;                  _______  _______
;                 |       \/       |
;     (+5V) Vdd --+ 1            8 +-- Vss (GND)
;                 |                |                      470
;   X1/CLKI/GP5 --+ 2            7 +-- GP0 (audio out) --/\/\/-- (spkr)
;    (not used)   |                |                  |   10K   1uF
;   X2/CLKO/GP4 --+ 3            6 +-- GP1             --/\/\/--|(-- (line)
;    (not used)   |                |  (not used)
;     GP3/!MCLR --+ 4            5 +-- GP2
;    (not used)   |  (PIC12C508)   |  (not used)
;                 +----------------+
;
;   This program generates a continuous stream of white noise through a
; speaker connected (via a 470-ohm series resistor) to pin GP0 of a
; PIC12C508.  It demonstrates an easy method for generating a seemingly
; random stream of bits. Hardware folks will probably recognize it as the
; tapped shift register technique covered in the CMOS Cookbook by Don
; Lancaster.
;
; Adapted from the original PIC16C54 (Parallax) version by Scott Edwards.
;
    list    p=12c508
    radix   dec
    include "p12c508.inc"

    __FUSES _MCLRE_OFF &_CP_OFF & _WDT_OFF & 0xFFE  ;Internal osc.

    cblock  0x07    ;Variables
        i       ;Loop counter
        x       ;Scratch
        y       ;Scratch
        sr0     ;32 bits of shift register
        sr1
        sr2
        sr3     ;/
    endc

    org      0x0            
;
;  PIC12C508 cold starts at 0XFFF (where it loads a factory-programmed
; internal osc. calibrate value).  It then rolls over to 0x0.
;
    movwf   OSCCAL
    goto    start
;
;  Subroutines in 12-bit PIC series must go on bottom page of ROM.
;
wait    movlw   35      ;Change this number for different sound if using
    movwf   i       ;'wait' rotuine (normally disabled).
loop    decfsz  i,F
    goto    loop
    retlw   0
;
;  Main code area traditionally starts at 0x100 on a 12-bit PIC.
;
    org     0x100

start   movlw   b'11000000'     ;Turn off T0CKI
    option                  ;/
    movlw   b'00000000'     ;Preset outputs to come up low
    movwf   GPIO            ;/
    movlw   b'00000000'     ;Set the I/O direction (all bits output)
    tris    GPIO

    clrf    sr0             ;Might as well start with a seed of 1.6E7.
    clrf    sr1
    clrf    sr2
    clrf    sr3
    incf    sr3,F           ;/
;
;   The main loop 'taps' is 24 CPU cycles.  At the 4MHz internal clock
; rate, the noise output is operating at a max. rate of about 21KHz.
;
taps    btfss   sr3,6           ;Get bits 18 and 31 for the feedback XOR.
    bcf     x,0
    btfsc   sr3,6
    bsf     x,0             ;Bit 31 -> x

    btfss   sr2,1
    bcf     y,0
    btfsc   sr2,1
    bsf     y,0             ;Bit 18 -> y

    movf    y,W             ;!(x XOR y) -> carry
    xorwf   x,F

    btfsc   x,0
    bcf     STATUS,C
    btfss   x,0
    bsf     STATUS,C        ;/

    rlf      sr0,F          ;32-bit shift
    rlf      sr1,F
    rlf      sr2,F
    rlf      sr3,F          ;/
;
;  Put a pseudorandom bit out to the speaker.  In this example, GPIO bit 0
; (pin 7 on the PIC12C508) is used.  Be sure to use a 470 ohm resistor for
; speaker or 10K or better for input to an op-amp/divider/whatever.
;
;  Also, to use all six GP bits for noise, just comment the following 4
; lines and uncomment the 5th and 6th lines.
;
    btfss   sr3,7           ;line 1
    bcf     GPIO,0          ;line 2
    btfsc   sr3,7           ;line 3
    bsf     GPIO,0          ;line 4

;       movf    sr3,W           ;line 5
;       movwf   GPIO            ;line 6

;
;  Uncomment the following 'call wait' to experiment with changing the
; 'texture' of the noise (see 'wait' routine, above).
;
;       call     wait           ;Optional delay routine to alter sound

    goto     taps           ;Ad infinitum...
;
;  That's all, folks!
;
    end

Not my code but Scott Rider is well respected in the PIC Community and I trust his work.

Cheers
Chris

Edit: Updated SF is doing strange things in the text field now.
This took several edits to fix all the new idiosyncrasies so watch out if you post formatted text.

[stan cartwright]

Cool. I was thinking of if random>127 then port on else port off.
Seems they make them. https://www.google.co.uk/search?q=white+noise+bicycle+horn&tbm=isch&source=iu&ictx=1&fir=xYNWqFZXeUW9OM%253A%252CV3TKp95lUX8TyM%252C_&usg=__IpCi1s_N_3Dtkw_G7g1Z7ucBT58%3D&sa=X&ved=0ahUKEwjTnaWjlsbZAhWR_aQKHZ2rAyEQ9QEIxAEwDQ#imgrc=xYNWqFZXeUW9OM:

[Peter]

Can't you just get a turbospoke? http://www.turbospoke.com/ :)

[Chris Roper]

Or a piece of plastic taped to the frame and interfering with the spokes.
Worked for me 50 years ago, everyone could hear me coming :)