Subject:
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Building an IR/ultrasound co-processor... (LONG)
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 23 Nov 1998 08:01:59 GMT
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Original-From:
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Clem Taylor <ctaylor@srtc.com[IHateSpam]>
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Viewed:
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3251 times
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Hi,
I'm in the process of building a combination IR and ultrasound
co-processor for my HandyBoard based robot. It's based on what Chuck
McManis did for his Cougar bot. My version will have forward and backward
looking IR and include the sampling and filtering for two Polaroid 6500
ranging modules (also forward and backward looking).
I'm in the parts acquisition and planning phase right now and was hoping
to bounce some of my ideas off the list prior to placing an order with
DigiKey for the last of the parts.
I'm planning on using the PIC16C77 because it has 2 CCR pins (ranging),
SPI (communication with HandyBoard) and plenty of IO pins.
Rough layout:
\ | /
- * - Each of the lines represents a Sharp IS1U60 and a
QEC233QT (\/-) or F5F1QT (|) pair.
- * -
/ | \ * = ultrasound transducer (base is 8x10in)
http://www.eecis.udel.edu/~ctaylor/gort_layout1.gif (a better picture)
Questions:
1) DigiKey doesn't sell the TPIC2701, any ideas on a replacement part
that DigiKey sells (I need 10 channels total)?
2) The IS1U60 datasheet has a 47 ohm resistor on the 5V supply and a
47uF cap between 5V and ground with a note that this should be as close
as possible to the sensor. I was planning on running ~10in long wires
from the PICProto to the IS1U60 and the IR LEDs, is this going to be a
problem? Do I need separate resistor/cap pairs for each sensor/led
pair or can I just connect all the 5V and ground lines in parallel?
3) The PICProto64 sheet shows C3 and C4 as polarized caps, for this I
would want to use tantalum caps?
4) Should the MCLR pullup resistor (R2) be 100 ohms?
5) Where can I find a cheap (but not to slow) EPROM eraser? We have a
really nice programmer at work, but we don't use EPROMs so we don't
have an optical eraser...
In case anyone cares, heres my current part list:
PICProto64 $16.95ea (from microEngineering Labs)
Support parts for PICProto64
LM340T-5.0-ND $.70ea
5V 1.0AMP regulator (REG1)
P4841-ND $0.18ea
22pF monolithic ceramic cap (C1&C2)
P2013-ND $.39ea
10uF tantalum cap (C3) ??
P2053-ND $.50ea
.1uF tantalum cap (C4) ??
SE3419-ND $1.20ea (example crystal in PIC databook)
Epson CA-301 9.8304M-C 9.8304Mhz crystal (Y1)
(* this really should be 9.728Mhz *)
100H-ND 5/$.27
100Ohm 5% carbon film resistor (R2, pullup for MCLK)
ED3740-ND $1.62ea (will get a bit of use, so I picked a nicer one)
40pin DIP solder tail socket from Mill-Max (for PIC)
(* also needs LED1 and R3, see below *)
PIC16C77/JW-ND $16.45ea
8K x 14 EPROM, 33 IO (8 A/D), 4.0v - 6.0v, max clock 20MHz, 40-CDip
(it looks like DigiKey out of stock on this part now :-()
LEDs
HLMP-17{00,19,90}QT-ND $.30ea $2.82/10 (Red, Yellow and Green LEDs)
1.8v, 7.5mA, 27mW, 25+- deg beam
QED233QT-ND $.38ea $3.53/10 (940nm IR LED)
1.5V, 100mA, 0.075mW, 18+- deg beam, 940nm
F5F1QT-ND $.43ea $4.00/10 (940nm IR LED)
1.7V, 60mA, 0.28mW, 35+- deg beam (sidelooker)
LED resistors
430H-ND 5/$.27 430ohm resistor (for HLMP-17{00,19,90}QT-ND)
(5v-1.8v)/7.5mA ~= 430ohm
36H-ND 5/$.27 36ohm resistor (for QED233QT-ND)
(5v-1.5v)/100mA ~= 36ohm
47H-ND 5/$.27 47ohm resistor (for F5F1QD-ND and IS1U60)
(5v-1.7v)/60mA ~= 47ohm
Sharp IS1U60 (from Marshall)
$3.18ea
Planned PIC16C77 pinouts: (every pin is used)
SPI interface:
SS <- 7 slave select
SCK <- 18 serial clock
SDI <- 23 serial data in
SDO -> 24 serial data out
Polariod ultrasonic ranging modules
CCP1 <- 17 front ECHO
CCP2 <- 16 rear ECHO
RE0 -> 8 INIT
RE1 -> 9 BINH
infrared interface
RA0 <- 2 IR sensor #0 front 0 FL left side looking
RA1 <- 3 IR sensor #1 front 45 FLC left
RA2 <- 4 IR sensor #2 front 90 FC center
RA3 <- 5 IR sensor #3 front 135 FRC right
RA4 <- 6 IR sensor #4 front 180 FR right side looking
RB0 <- 33 IR sensor #5 rear 180 RR right side looking
RB1 <- 34 IR sensor #6 rear 225 RRC right
RB2 <- 35 IR sensor #7 rear 270 RC center
RB3 <- 36 IR sensor #8 rear 315 RLC left
RB4 <- 37 IR sensor #9 rear 360 RL left side looking
RD0 -> 19 IR LED #0 front 0 FL left side looking
RD1 -> 20 IR LED #1 front 45 FLC left
RD2 -> 21 IR LED #2 front 90 FC center
RD3 -> 22 IR LED #3 front 135 FRC right
RD4 -> 23 IR LED #4 front 180 FR right side looking
RC6 -> 25 IR LED #5 rear 180 RR right side looking
RC7 -> 26 IR LED #6 rear 225 RRC right
RB5 -> 38 IR LED #7 rear 270 RC center
RB6 -> 39 IR LED #8 rear 315 RLC left
RB7 -> 40 IR LED #9 rear 360 RL left side looking
status
RE2 -> 10 STATUS0 LED left bump
RC0 -> 15 STATUS1 LED front bump
RD5 -> 28 STATUS2 LED right bump
RD6 -> 29 STATUS3 LED back bump
RD7 -> 30 STATUS4 LED special
Thanks,
Clem
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