'
' Propeller Ultrasonic Send and Receive with display on a VGA Monitor
'
' by Richard Jones rjtp<atsym>ihug.co.nz
'
' V1.0 18th February 2008
'
' This program uses the Propeller Proto Board
'
' The ultrasonic sender is energised briefly at the beginning of the scope trace.
' The ultrasonic receive signal is digitized and the samples are displayed on a VGA monitor, just like
' an oscilloscope with trigger from the emitted pulse.
'
' This program is based on the Microphone to VGA demo from Parallax.
'
'
' ┳ +3v3
' 1n
' P0 ─────────╋ 0.1u
' 5k6 ┣────┐
' P1 ───────╋ │ Receiver Sender \ ┌────────P7
' 1n O| MA40A3R MA40A3S []
' │ │ MuRata MuRata / └────────P6
' 0v ─┻─────┻─
' A-D Convertor Sender
'
' Note 1. R & C's must be v close to propellor pins.
' Note 2. Ultrasonic sender and receiver from Surplustronics in Auckland
' Note 3. A->D conversion details may be found here:
' http://www.parallax.com/Portals/0/Downloads/appnt/prop/AN001-PropellerCountersv1.1.zip
'
CON
_clkmode = xtal1 + pll16x
_xinfreq = 5_000_000
tiles = vga#xtiles * vga#ytiles
tiles32 = tiles * 32
apin_sonic = 6 ' ultrasonic output pin a
bpin_sonic = 7 ' ultrasonic output pin b (in antiphase to a)
OBJ
vga : "vga_512x384_bitmap"
VAR
long sync, pixels[tiles32]
word colors[tiles], ypos[512]
PUB start | i
'start vga
vga.start(16, @colors, @pixels, @sync)
'init colors to cyan on black
repeat i from 0 to tiles - 1
colors[i] := $3C00
'fill top line so that it gets erased by COG
longfill(@pixels, $FFFFFFFF, vga#xtiles)
'implant pointers and launch assembly program into COG
asm_pixels := @pixels
asm_ypos := @ypos
cognew(@asm_entry, 0)
repeat
CON
' At 80MHz the ADC sample resolutions and rates are as follows:
'
' sample sample
' bits rate
' ----------------
' 9 156 KHz
' 10 78 KHz
' 11 39 KHz
' 12 19.5 KHz
' 13 9.77 KHz
' 14 4.88 KHz
bits = 9 'try different values from table here
attenuation = 0 'try 0-4
averaging = 13 '2-power-n samples to compute average with
DAT
'
'
' Assembly program
'
org
asm_entry mov dira,asm_dira_us 'make pin p1 (ADC) output
movs ctra,#0 'POS W/FEEDBACK mode for CTRA
movd ctra,#1
movi ctra,#%01001_000
mov frqa,#1
mov xpos,#0
mov asm_cnt,cnt 'prepare for WAITCNT loop
add asm_cnt,asm_cycles
:loop waitcnt asm_cnt,asm_cycles 'wait for next CNT value (timing is determinant after WAITCNT)
mov asm_sample,phsa 'capture PHSA and get difference
sub asm_sample,asm_old
add asm_old,asm_sample
add average,asm_sample 'compute average periodically so that
djnz average_cnt,#:avgsame 'we can 0-justify samples
mov average_cnt,average_load
shr average,#averaging
mov asm_justify,average
mov average,#0 'reset average for next averaging
:avgsame
max peak_min,asm_sample 'track min and max peaks for triggering
min peak_max,asm_sample
djnz peak_cnt,#:pksame
mov peak_cnt,peak_load
mov x,peak_max 'compute min+12.5% and max-12.5%
sub x,peak_min
shr x,#3
mov trig_min,peak_min
add trig_min,x
mov trig_max,peak_max
sub trig_max,x
mov peak_min,bignum 'reset peak detectors
mov peak_max,#0
:pksame
cmp xpos, #0 wz
if_nz jmp #:not_start
' Initiate Output of a few cycles at 40kHz on apin and inverted on bpin
' mov dira,asm_dira_us 'set ultasonic pins to output
mov phsb, #0
mov frqb, asm_frqb
mov ctrb, asm_ctrb
:not_start cmp xpos, #$20 wz
if_nz jmp #:not_end
' mov dira,asm_dira_oc 'set ultasonic pins to open circuit
mov ctrb, #0 ' disable 40kHz output pins
:not_end mov mode,#1 'flag pulse sent
sub asm_sample,asm_justify 'justify sample to bitmap center y
sar asm_sample,#attenuation 'this # controls attenuation (0=none)
add asm_sample,#384 / 2
mins asm_sample,#0
maxs asm_sample,#384 - 1
mov x,xpos 'xor old pixel off
shl x,#1
add x,asm_ypos
rdword y,x 'get old pixel-y
wrword asm_sample,x 'save new pixel-y
mov x,xpos
call #plot
mov x,xpos 'xor new pixel on
mov y,asm_sample
call #plot
add xpos,#1 'increment x position and mask
and xpos,#$1FF wz
if_nz jmp #:loop
mov mode,#0 'if rollover, reset mode for trigger
mov xpos,#0
jmp #:loop 'wait for next sample period
'
'
' Plot
'
plot mov asm_mask,#1 'compute pixel mask
shl asm_mask,x
shl y,#6 'compute pixel address
add y,asm_pixels
shr x,#5
shl x,#2
add y,x
rdlong asm_data,y 'xor pixel
xor asm_data,asm_mask
wrlong asm_data,y
plot_ret ret
'
'
' Data
'
asm_cycles long |< bits - 1 'sample time
'asm_cycles long 380 'sample time
asm_dira_us long $000002c2 'output mask p0=adc ip,p1=adc op, p6,p7 ultrasonic output
asm_dira_oc long $00000200
asm_pixels long 0 'pixel base (set at runtime)
asm_ypos long 0 'y positions (set at runtime)
average_cnt long 1
peak_cnt long 1
peak_load long 512
mode long 0
bignum long $FFFFFFFF
average_load long |< averaging
asm_frqb long $8000_0000 / 1000 'Set FRQ so PHS[xx] toggles @40kHz
asm_ctrb long ( %00101_000 << 23 ) + ( bpin_sonic << 9 ) + apin_sonic 'Establish mode and APIN / BPIN
asm_time long 0
asm_delay long 10
asm_justify res 1
trig_min res 1
trig_max res 1
average res 1
asm_cnt res 1
asm_old res 1
asm_sample res 1
asm_mask res 1
asm_data res 1
xpos res 1
x res 1
y res 1
peak_min res 1
peak_max res 1
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