gmane.comp.hardware.microcontrollers.pic

[OT]Interesting research for NZ quake susceptability

cdb — 2012-05-26T00:57:47

 Victoria University (Wellington, North Island) has been doing research 
into the south island quakes along the Alpine Fault. They've dicovered that 
NZ is constantly shifting with ongoing long lasting (30 minutes) quakes at 
a depth of 45 klm below the surface.

article here 
:http://www.abc.net.au/science/articles/2012/05/24/3510050.htm?topic=enviro
&WT.svl=healthscience5
--
cdb,  on 26/05/2012

[EE] possible ways of dealing with noise on a serial bus ?

Jason White — 2012-05-25T19:05:16

This question is completely theoretical. I'm just curious as it
pertains to something
I may be building in the near future.

Lets say I have 25 devices spread throughout a building connected through a
low speed (50Khz) synchronous serial bus at 5 volts. Lets say we have 50 feet
(or so) of cable sloppily daisy chained in between each of the devices
(around high
amounts of florescent lighting). Would noise be a likely issue with
the bus ? If so
what would be an effective way of dealing with it. (differential
signaling, perhaps ?)

Thanks
Jason White

Re: [OT] Anyone from San Diego, CA?

Chris Pearson — 2012-05-25T17:19:41

Hi Tamas,



I’m actually relatively new to the San Diego area myself so I was going to
see if we had any native San Diegans who wanted to comment before me but I
see not. So I’ll take a crack at it. I moved to North County from MN about
two and a half years ago. The company I work for is based out of Vista. I
briefly lived just north of San Diego County when I moved here; I've been
in Oceanside now for almost 2 years, and am currently looking for places in
the San Marcos area. My sister recently moved from LA to the South Park
neighborhood of SD. I’m about 45 minutes – 1 hour north of her and she’s
pretty darn close to the heart of SD.



The best electronics component shop I’ve found by far is Fry’s Electronics.
I’m a regular at the one in San Marcos; there is one in SD proper as well.
For tools beyond Fry’s scope there is Harbor Freight, Sears, a few
independent shops and Matco/Snap-On/Mac, etc tool trucks all over.



Here’s the “standard” list of places to see (in no particular o

Re: [PIC]:Difference between BOR and LPBOR

Marcel Duchamp — 2012-05-25T15:45:45


Dwayne,

Please keep us informed of your progress if you proceed with this.  I've 
been interested in those parts for some time and would like to know how 
it works out.

Thanks!

Re: [PIC]:Difference between BOR and LPBOR

Dwayne Reid — 2012-05-25T15:10:25

I had problems with exactly these modules on my 
recent 10F322 project - the chip would go into 
reset if the supply voltage was less than about 
2.4V.  Disabling both the BOR and LPBOR modules 
allowed the chip to run from a pair of NiMh 
cells.  The datasheet doesn't talk about the 
LPBOR module, which is why it took me so long to 
try disabling that config bit and thus solving my problem.

I also had problems when I was using the device 
header for that chip (AC244045?) - this would 
also not run at low supply voltages when used 
with the PICkit3.  I opened a trouble ticket with 
Microchip Tech Support - it took them a while but 
they confirmed that problem and also told me that 
this does NOT appear to be a problem when the 
ICD3 is used instead of a PK3.  Tech support says 
that they expect to fix this problem with the PK3 
by way of a firmware update at some future time.

I had also asked Tech Support for documentation 
regarding the LPBOR module but have not yet had 
any response to that particular re

[OT] Spacex delivers a Dragon to ISS

Walter Banks — 2012-05-25T15:00:30

I have been a big fan of SPACEX for a long time. As a company they have
practiced a lot of solid engineering and science in developing their
various space technologies. They have shown tremendous attention to
details in the work they have done.

Spacex has demonstrated that they learn from their mistakes and they
have not let any pressures force them to do anything that they feel not
fully prepared for.

This mornings capture of the Dragon capsule by ISS has demonstrates how
this approach has paid off.

As one of many companies moving into the space transportation business
we are seeing a new era in space exploration that will not be dominated
by just finding a solution but in selecting which innovation solution
should be pursued.

The possibilities start to get interesting with Rutan/Virgin preparing
to carry passengers into space for a short time and private companies
soon to routinely launch and support space missions.


Walter..

Re: [EE] TV Tuner Based Spectrum Analyzer

Sean Breheny — 2012-05-25T14:40:14

For what it's worth, I think that you are basically on the right
track, Herbert. Good Tektronix or HP spectrum analyzers have
resolution bandwidths down to at least 1kHz and many go down to 100Hz
or even 10Hz (or even lower but that is almost always done in
post-processing by digitizing and then doing an FFT on each block of
samples).

You will see the terms "resolution bandwidth (RBW)" and "video
bandwidth (VBW)". Then there is also averaging or peak detection on
top of this. The distinction is as follows: RBW is the bandwidth of
the RF chain before the detector (power measurement device). VBW is
the bandwidth of the signal chain after the detector. Averaging or
peak detection then refer to how the digital storage portion of the
device records samples - it takes several samples per time step and
saves only one sample and it can save either the average of the
samples or the highest one.

The RBW determines the RF noise floor and also how close two signals
can be and still be resolved by the analyzer into two

RE: [EE] TV Tuner Based Spectrum Analyzer

Joe McCauley — 2012-05-25T13:07:34

A bit removed from what the OP wanted, but.... This was not designed as a spectrum analyser, but you can get a nice spectrum between 45MHz & 870MHz. Takes 45 seconds to get a full range spectrum though!

http://www.e-callisto.org/

We use them for solar monitoring at http://www.rosseobservatory.ie. I tried to attach 2 spectra, but the list would not let them pass. If anyone wants to see, I can send directly to them as an attachment.

One of these shows frequencies below 45MHz, an up converter was used for this part.

Another option might be http://www.funcubedongle.com/. I've not used one (its on my long list of cool things to try) so I don't know if spectrum analyser type output is possible.

Joe


-----Original Message-----
From: piclist-bounces< at >mit.edu [mailto:piclist-bounces< at >mit.edu] On Behalf Of Dwayne Reid
Sent: 24 May 2012 22:49
To: Microcontroller discussion list - Public.
Subject: Re: [EE] TV Tuner Based Spectrum Analyzer

Have you checked out the "Poor Man's Spectrum Analyzer" at <www.science-works

Re: [EE] How would you ensure fast powerup rise time?

Spehro Pefhany — 2012-05-25T11:43:59


So the chip has a lousy internal reset circuit, but no reset pin.

You could use a supervisor chip after the regulator (eg. MCP101T) 
driving a MOSFET
high side switch such as a Si2301.

Ideally, run everything through the high-side switch- otherwise something else
in the circuit may partially power up the chip before Vdd turns on (through the
internal protection networks), which could certainly screw up the 
reset or even
cause latch-up and destruction of your magical mystery chip. Best to 
not do that.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff< at >interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

[PIC]:Difference between BOR and LPBOR

Ruben Jönsson — 2012-05-25T09:15:12

Hi,

I have been studying the datasheets for some of the PIC10/12LF parts. These 
have both the standard Brown Out Reset (BOR) and also a Low Power BOR (LPBOR). 
I can't seem to find any difference between these (not even difference in 
current consumption).

The datasheets are marked as preliminary and no graphs or charts are available. 
Having both a standard BOR and also an LPBOR seems to indicate that there are 
some drawbacks using the LPBOR over the BOR. Why would there otherwise be both 
in the same chip?

I have an idea of using one of these chips for power management for cheap solar 
PV cells with low capacity NiMh batteries. These work fine when the batteries 
are somewhat charged but when the batteries are almost completely discharged, 
the circuit hangs in a mode where more current is drained than can be supplied 
by the PV cell so the batteries never gets charged and the circuit won't come 
alive again, no matter how much sunshine there is.

I did a circuit that senses the voltage drop on the ba

Re: [EE] How would you ensure fast powerup rise time?

Electron — 2012-05-25T08:09:05

Nope, that would be wonderful if I had.. but none are left. :(



Well, even if it wasn't, it would introduce a voltage drop, which for analog
parts that have to be sampled by the ADC, like this, would introduce errors.



Yup it someway comforted to know that I tried every possibile way, but in the
end it seems that the PMOS driven by NPN (to invert input logic level) driven
by the ~Error output of the Vreg is the best overall solution, given the 3 goals
of being as cheap as possible, occupying as little space as possible, and to
keep component count as low as possible (as I do hand solder every board).

I'm still waiting for the reply from the IC design engineer, if it was possible
to reset it via a Sleep cycle, I could tie it to the ~Error output directly and
would be a fantastic solution. But the IC has a bug that if power doesn't ramp
quicker than 100 uS, the IC won't load its registers correctly in case the temp
is very cold.. argh, damn bugs, one should read the erratas BEFORE the datasheet,
but I al

Re: [EE] TV Tuner Based Spectrum Analyzer

Herbert Graf — 2012-05-25T03:38:20

I have seen that before. That site seems to just offer for purchase the details, or parts.

I will have a look to see what kind of hits "poor mans spectrum analyzer" gets me. Thanks for the pointer.

TTYL


On 2012-05-24, at 5:48 PM, Dwayne Reid wrote:

Re: [EE] TV Tuner Based Spectrum Analyzer

Dwayne Reid — 2012-05-24T21:48:55

Have you checked out the "Poor Man's Spectrum Analyzer" at 
<www.science-workshop.com/> ?  They may have circuit blocks that are 
useful for you.

Searching out "poor mans spectrum analyzer" yields lots of hits - 
some of those may also be useful.

dwayne


At 01:15 PM 5/24/2012, Herbert Graf wrote:

Re: [EE] How would you ensure fast powerup rise time?

Robert Rolf — 2012-05-24T21:45:43

Do you have a spare pin you could use to drive a PFET or transistor on your
fussy chip's power rail?
Then you would be able to reset the device at will (assuming that you set
all other pins connected
to it to low).
You say you need 100mA which is too much for a PIC pin, but I have used PIC
pins to directly switchable power
to low current drain devices. With a series inductor and small cap to
filter out noise you get a decent
switchable power line.

Re: [EE] How would you ensure fast powerup rise time?

Electron — 2012-05-24T20:06:25

Dear David,

At 15.49 2012.05.24, you wrote:

Believe me I did and I did it not only for the LP2951 (my choice then) but
also for tens and tens of other possible Vregs. Although the function you
mention would be very useful to many (considering that some chips are very
demanding about power up ramp times), the only such chip that I found after
extensive datasheet's (tens and tens!) reading is the MCP1791. However, it
takes 200uS to ramp up while I need 50 (from 30 to 80  max), moreover it
needs at least 6V to "startup", defying its LDO qualities, although only at
startup. Maybe for another project I will remember of it, it's a very nice
Vreg and I suggest you all to take a look at it, it's nice and not too
expensive. Page 15 of the data sheet describes this low voltage shutdown
feature: http://ww1.microchip.com/downloads/en/devicedoc/22075a.pdf



Component count is terrible, the first even needs two LP2951's! It's not
that I'm not able to design a low voltage shutdown output circuit, it's
that I need to ke

[EE] TV Tuner Based Spectrum Analyzer

Herbert Graf — 2012-05-24T19:15:29

Hello all,

well, after a long delay, I've been able to dedicate a little time to my
idle project: a home built spectrum analyzer based on a TV tuner front
end.

I've found what I believe the perfect tuner for me (mostly because it's
something I have in my hands):

http://www.datasheetarchive.com/indexdl/Datasheet-028/DSA00488547.pdf

It's a Temic 4036 RF front end module. I found it on a WinTV PC TV tuner
PCI card. 

It's a I2C based tuner, with single 5V power supply (has an onboard
DC-DC to get the 33V needed by the tuner). I stuck the card in a PC,
booted Ubuntu, attached a protocol analyzer (thank you beta version of
the BitScope software, was a major time saver!) on the I2C pins, started
TVTime and changed channels. The module is being programmed exactly as
the datasheet says it should be!

So, with that out of the way, what would be my next step?

First off, the module outputs CVBS (at baseband), and something labelled
IF2 (at 45.75 MHZ). Obviously I need an RSSI circuit. But do I first
have to "tune"

Re: [PIC]: PIC32 for camera capture

Andre Abelian — 2012-05-24T17:14:22

thanks Mark..

________________________________
 From: Mark Hanchey <mark< at >pixeltrickery.com>
To: piclist< at >mit.edu 
Sent: Wednesday, May 23, 2012 3:00 PM
Subject: Re: [PIC]: PIC32 for camera capture

On 5/21/2012 5:13 PM, Andre Abelian wrote:
The Pic isn't up to that task , not at 5mp resolutions. You really need 
something with dedicated dsp abilities to start manipulating data like 
that .  Here is a site about open source cameras for micros, even there 
best designs cannot do 5mp and they are involving ARM chips.

http://www.cmucam.org/

If it were me I wouldn't do 5mp as that high a resolution isn't needed 
to do motion detection, 640x480 can do that easily and color also isn't 
needed.
Mark

Re: [OT] Interesting newish embedded programming language

Peter Johansson — 2012-05-24T16:04:11


it might make a nice embedded language as well.  I have also noticed
that the GO language has been merged into the official GCC 4.7
codebase.  Does anyone happen to know if there are any efforts to get
GO support with any of the uC code back-ends for GCC, PIC or
otherwise?

-p.

Re: [EE] Raspberry Pi challengers

Mark Hanchey — 2012-05-24T12:20:05

Close up pic of the board is here:
http://www.viagallery.com/Downloadimage.aspx?name=APC%20-%20Top.jpg&cat=5 <http://www.viagallery.com/Downloadimage.aspx?name=APC%20-%20Top.jpg&cat=5>

Chip is wondermedia WM8750
http://www.wondermedia.com.tw/en/products/platform/soc/wm8750/

Sadly wondermedia is about as open as Broadcom about information.

Mark

Re: [EE] Looking for decent but small camera

Mark Hanchey — 2012-05-24T11:50:53

I purchased a canon S150is last year and have been very happy with it. 
One of the cool things about canon cameras
is that it is possible to load alternative firmware using chdk. It 
doesn't replace the cameras firmware , it is placed on the card and the 
camera will load it and run it as long as the power is on, when powered 
off and the card removed the camera will revert to its main firmware. It 
adds a lot of features like the ability to save pics as RAW, exposure 
settings, bracketing, longer exposure times, etc.

http://chdk.wikia.com/wiki/CHDK

Mark

Re: [OT] Interesting newish embedded programming language

Yigit Turgut — 2012-05-24T11:20:53

I vote for ώψπε++-+. Everything has it's ups and downs right ?

On Thu, May 24, 2012 at 9:01 AM, cdb <colin< at >btech-online.co.uk> wrote: