Searching \ for ' [PIC] School Project - Flight Data Acqui' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/microchip/memory.htm?key=data
Search entire site for: 'School Project - Flight Data Acqui'.

No exact or substring matches. trying for part
PICList Thread
'[PICLIST] [PIC] School Project - Flight Data Acqui'
2002\04\07@035157 by Lindsay Pallickal

flavicon
face
Hi All,

   I've been lurking around on this list for a couple years and am finally
about to embark on my first serious PIC project. It is a university project.
A group of aeronautical engineering students and I want to build a tiny
black box for a model airplane, to aquire 8-12 channels of analog data.
Before I ask my questions, here is what I have planned to use so far:

16F877 for 8 channels, 10 bits
24FC256 serial eeprom - 256k of data storage
PICALL Programmer

   This should provide at least 10 min of storage at 30 samples/sec, using
3 bytes for every 2 samples. My main concern is that we may need more
channels, up to 10 or 12. I see at least one 16 and some 17 and 18 series
PICs that are up for the job. I have two concerns about these alternate
chips though, these parts aren't the flash type - I noticed they use the 'C'
denotation instead of the 'F' in their names - does this mean for every code
revision I will need a new chip?

   Also, for the 17 and 18 series chips it seems I will need a different
programmer. Is there a cheap programmer for the 17 and 18 series chips that
I should go with from the start?

   I was also considering using a pin on the 16F877 to switch between two
sets of 8 analog inputs, using eight 2x1 muliplexers. I would read 8
channels into RAM, switch with the muxes, read the second 8 channels to RAM,
and then output to the eeprom. Would that work? I've never heard of
multiplexers switching analog inputs, so I am a little concerned there.

   I'm hoping you guys will point out anything obviously mistaken and maybe
offer some ideas. Sorry if I sound like a total newbie by asking so many
questions, I am one - most of my experience is in computer science and I've
only been reading the EE related stuff, though I have been doing so for a
while. Thanks in advance.

Lindsay

P.S. For the curious, here is some non-essential information, the data we
hope to acquire:
3 axes - Accelerometer
3 axes - Gyroscope
Rudder Angle
Elevator Angle
Aileron Angles - 2 channels
Flap Angle
Engine Speed

The gyroscope and accelerometer (donated, thank goodness!) data will
definitely be acquired, while it is yet to be decided which of the later 5
will be acquired. We'd like to get everything, 12 channels total.

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\04\07@095619 by Patrick J

flavicon
face
Hi Lindsay,

> PICs that are up for the job. I have two concerns about these alternate
> chips though, these parts aren't the flash type - I noticed they use the 'C'
> denotation instead of the 'F' in their names - does this mean for every code
> revision I will need a new chip?

Yes it does, unless you get a windowed part (JW) which you can erase with
UV-light.

> I've never heard of
> multiplexers switching analog inputs, so I am a little concerned there.

There are such devices avail, not too expensive either. I used such for
a projetc switching video (analog ) signals. I guess it all depends on how
accurate u need it to be and PCB realestate.

>     I'm hoping you guys will point out anything obviously mistaken

Sounds to me like u're on track :-)

> Thanks in advance.
> Lindsay

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\04\07@095628 by Byron A Jeff

face picon face
On Sun, Apr 07, 2002 at 04:43:57AM -0400, Lindsay Pallickal wrote:
> Hi All,
>
>     I've been lurking around on this list for a couple years and am finally
> about to embark on my first serious PIC project. It is a university project.
> A group of aeronautical engineering students and I want to build a tiny
> black box for a model airplane, to aquire 8-12 channels of analog data.
> Before I ask my questions, here is what I have planned to use so far:
>
> 16F877 for 8 channels, 10 bits
> 24FC256 serial eeprom - 256k of data storage
> PICALL Programmer
>
>     This should provide at least 10 min of storage at 30 samples/sec, using
> 3 bytes for every 2 samples. My main concern is that we may need more
> channels, up to 10 or 12. I see at least one 16 and some 17 and 18 series
> PICs that are up for the job. I have two concerns about these alternate
> chips though, these parts aren't the flash type - I noticed they use the 'C'
> denotation instead of the 'F' in their names - does this mean for every code
> revision I will need a new chip?

Not exactly. The EPROM based controllers always come in two packages. The
JW part is windowed and can be erased. The OTP part con only be progrmmed
once.

>
>     Also, for the 17 and 18 series chips it seems I will need a different
> programmer. Is there a cheap programmer for the 17 and 18 series chips that
> I should go with from the start?

Not sure about the 18's. The 17's have the original parallel programming
algorithm IIRC. Between that and the fact that they're simply not very
popular, you're going to have a hard time finding a useful inexpensive
programmer for them. Also you'll have to expand your toolset.

>
>     I was also considering using a pin on the 16F877 to switch between two
> sets of 8 analog inputs, using eight 2x1 muliplexers. I would read 8
> channels into RAM, switch with the muxes, read the second 8 channels to RAM,
> and then output to the eeprom. Would that work?

Well you'll have some issues. The first you have right on the mark below.

> I've never heard of
> multiplexers switching analog inputs, so I am a little concerned there.

And rightly so. The second thing is to ensure that your multiplexer doesn't
affect the reading.

>
>     I'm hoping you guys will point out anything obviously mistaken and maybe
> offer some ideas. Sorry if I sound like a total newbie by asking so many
> questions, I am one - most of my experience is in computer science and I've
> only been reading the EE related stuff, though I have been doing so for a
> while. Thanks in advance.

Actually this is a pretty good first crack at the nut. However you missed the
patently simple and obvious solution: Why not simply add a second 16F87X
part to the mix? For example the 28 pin package adds 5 more analog inputs
to the mix. It can easily be attached to the 16F877 using a high speed serial
interface, or in fact could write to it's own data EEPROM if you like. But
you get the same programmer, no need to switch chips, and it'll cost just
about as much space as the multiplexer solution you proposed (3 pins per
multiplexer + power + select is 27 pins, round up to 28)

It'll only get you to 13 analog inputs, but that exceeds your original
specification. You can even use another 40 pin 16F87X part and get 16 analog
inputs.

Hope this helps,

BAJ

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\04\07@102900 by Dave Dilatush

picon face
Lindsay Pallickal wrote...

>I've never heard of multiplexers switching analog inputs,
>so I am a little concerned there.

Why the concern?  To multiplex digital signals, you use a digital
multiplexer; to multiplex analog signals, you use an analog
multiplexer.  It's that simple.

Analog switches and multiplexers are as common as cat-dirt and
nearly as cheap.  Three that are often used are the 74HC4051 8:1
Analog Multiplexer, 74HC4052 Dual 4:1 Analog Multiplexer, and
74HC4053 Triple 2:1 Analog Multiplexer.  All are in 16-pin
packages, and should cost you just a bit over 50 cents apiece in
low quantities.

They're available from numerous manufacturers.  Fairchild
Semiconductor has a datasheet which covers all three, at:

http://www.fairchildsemi.com/ds/MM/MM74HC4051.pdf

My quick take on your situation is that you would be best off
using a pair of 74HC4052s to multiplex 16 analog inputs onto four
PIC a/d input pins, with another two pins used as digital outputs
to control the multiplexer chips.

That gives you 16 analog inputs using only 6 PIC pins.

Hope this helps...

Dave

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\04\07@120342 by Herbert Graf

flavicon
face
{Quote hidden}

       Is this a one off or will it go into production? Since you are already
thinking of adding a second chip (the mux) how about adding an I2C ADC?
Maxim has an 8ch 10bit one that would fit the bill perfectly, and since you
are already doing I2C (for the EEPROM) adding it would be trivial from a
hardware and code point of view? Thanks, TTYL

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\04\07@142123 by Benjamin Bromilow

flavicon
face
Personally, I'd do a 2*16F87x approach with two EEPROMs. You'ld be able to
sample twice as quickly for one thing-EEPROMs aren't that fast though 30/s
shouldn't be a problem if my mental maths isnt too bad! Having two PICs
share a serial port has been discussed on the list before. Have both PICs
listen to Rx, only one at a time use Tx depending upon what data packet the
PC has "asked" for. The code would therefore be very similar between the two
PICs. Infact, I'd probably use an unsed pin on the pics to decide if it was
PIC #1 or #2 so that the code could be the same for the two PICs with only a
wire link difference between the two bits of hardware. Using the '877 for
the A/D ports would leave alot of pins free so I'd probably be tempted to
use a few pins to code for PIC # ID so that the whole system was expandable.
I'm planning something similar for an automotive data logger and I
definately want it to be expandable.....

Ben

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\04\07@143402 by Herbert Graf

flavicon
face
> Personally, I'd do a 2*16F87x approach with two EEPROMs. You'ld be able to
> sample twice as quickly for one thing-EEPROMs aren't that fast though 30/s
> shouldn't be a problem if my mental maths isnt too bad!

       IIRC the EEPROM he is using has a write time of 20ms, very long if you are
writing byte by byte (only 50bytes/sec) but pretty quick if you write 64
byte page by 64 byte page at a time (which is what I do). TTYL

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\04\07@185235 by Tony Nixon

flavicon
picon face
Lindsay Pallickal wrote:

> 24FC256 serial eeprom - 256k of data storage

Are you expecting this chip to be 256K bytes or 256K bits??

Just a thought to stop some frustration :-)

The largest serial EEPROM I've heard of is 128K bytes, although that
could be wrong.

--
Best regards

Tony

mICros
http://www.bubblesoftonline.com
spam_OUTsalesTakeThisOuTspambubblesoftonline.com

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\04\07@193617 by Glen Wiley

flavicon
face
Microchip has 512K serial EEPROMs, one of the most exciting is
the 24FC515 - an 8P DIP with 64Kx8 bit storage and clocking at
up to 400kHz.

On Mon, Apr 08, 2002 at 08:50:01AM +1000, Tony Nixon wrote:
{Quote hidden}

--
Glen Wiley

Everything should be made as simple as possible, but not
simpler. -- Albert Einstein

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\04\07@195335 by Herbert Graf

flavicon
face
> Lindsay Pallickal wrote:
>
> > 24FC256 serial eeprom - 256k of data storage
>
> Are you expecting this chip to be 256K bytes or 256K bits??

       I don't think so, the person said they figured it would give them about 10
minutes of storage, I did the math based on 32k bytes and it came out to
about 12 minutes, so it appears the person does realize it's 256k bits = 32k
bytes. TTYL

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\04\08@051112 by Lindsay Pallickal

flavicon
face
   Whoa! Thanks for pointing this out, I completely missed that. I will
have to go with 4 to 8 of the 512 Kilobit chips it seems, though I can't
seem to find where to buy it - Digikey wants a minimum of 360 units ordered.
In fact most places seem to want a minimum order quantity, except arrow
electronics, which isn't listed at microchip.com for all parts.

   One poster said these chips have a 20ms write time. I see 5ms in the
manual though. With the 64 byte write mentioned by the same poster though,
there should be enough time to write all the data, with 20ms or 5ms write
times.

   Another question, are there alternative serial chips out there with more
storage? It could even be volatile storage, since I can make it a
requirement that the data be downloaded to a laptop immediately after
acquisition. I suppose a parallel type chip would do too, but I get the
impression serial is easier to work with for a beginner.

   Thanks to all for the suggestions on adding extra channels, I've already
picked up a lot from these discussions. I am leaning toward the mux solution
for the additional channels, maybe with a daughterboard full of muxes that
can be replaced to add more channels in the future.

Lindsay

{Original Message removed}

2002\04\08@203019 by Andrew Warren

flavicon
face
Herbert Graf <PICLISTspamKILLspammitvma.mit.edu> wrote:

> the EEPROM he is using has a write time of 20ms, very long if you
> are writing byte by byte (only 50bytes/sec) but pretty quick if you
> write 64 byte page by 64 byte page at a time (which is what I do).

   It's even faster if he can interleave writes to multiple EEPROMs
   in his circuit... Which is an argument for using many small
   EEPROMs rather than a single big one.

   With 8 EEPROMs, he can write 64 * 50 * 8 = 25,600 bytes per
   second.

   -Andy

=== Andrew Warren -- .....aiwKILLspamspam.....cypress.com
=== Principal Design Engineer
=== Cypress Semiconductor Corporation
===
=== Opinions expressed above do not
=== necessarily represent those of
=== Cypress Semiconductor Corporation

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


More... (looser matching)
- Last day of these posts
- In 2002 , 2003 only
- Today
- New search...