In the arena of high altitude balloons, Canon’s PowerShot series of digicams are the camera du jour for sending high into the stratosphere. There’s a particular reason for this: these cameras can run the very capable CHDK firmware that turns a $100 digicam into a camera with a built-in intervalometer along with a whole bunch of really cool features. It appears this CHDK firmware is much more powerful than we imagined, because [Chris] is now transmitting pictures taken from a Canon a530 to the ground, using only the CHDK firmware and a cheap radio module.
These PowerShot cameras have an ARM processor inside that runs VxWorks, a minimal but very capable OS for embedded devices and Mars rovers. By tying in to the Tx and Rx lines of the camera, [Chris] can issue commands to the OS, change settings, and even install his own code.
With the help of [Phil Heron]’s SSDV encoder written in C, [Chris] was able to get the camera to transmit images with a small radio transmitter that fits in the battery compartment. Right now, [Chris] has only built the CHDK + SSDV for the Canon a530, but with how useful this build is, we expect to see an improved version very shortly.
That is really cool. I don’t know why cameras don’t include intervalometer functions to begin with. I guess it’s a matter of price or simplicity.
I think it’s an issue of support. If you put a feature in a product, you need to test it, you need to write up instructions in the manual. You have to teach your tech support people how to field questions about it. I think Canon is taking just the right approach by allowing people to update the firmware and add their own features, this way they can make lots of people happy with little effort on their part.
CHDK doesn’t touch the firmware. It is booted off sdhd card every time the camera is restarted.
My nikon D7000 and my nikon D4 both do and i think all the newer icons … but thats all i have seen
nikons* stupid autocorrect
Extremely cool hack.
i love the design and i love the way he fit it all in but i have to ask … why was it necessary to put the batteries on the outside and the components on the inside instead of just leaving the batteries in and putting the xmitter on the outside?
So you can change the batteries easily and re-purposing the empty void left behind.
and in hindsight you get a nice case for your electronics where you dont need such a case for the batteries
but thanks!
It’s also handy if you want to use more than two AA cells.
I’ve had this very camera since 2006 & was increasingly close to pensioning it off due to it’s battery drain (2 x AA ) & pickiness on supply voltage. 2 x 1.2V NiMH just didn’t cut the mustard with it… However it’s had a wonderfully new lease of life since I simply fitted a single 700mAh 3.2V LIFePO4 AA 14500 rechargeable cell,costing US$3, along with a place holding straight thru’ dummy. SAee a similar apparoch => http://www.instructables.com/id/Single-AA-LiFePo4-cell-powered-project-in-a-parti/step5/Alerts-/
These cheap LiFePO4 cells retain an extremely flat discharge until near exhausted, yet are quite tolerant of on the fly charging (that may come from a solar panel when aloft)..It strikes me hence the author may care to do the same?
However, if you try to charge the cell with the camera, you risk a fire because NiMH chargers are designed to trickle charge once full, which causes lithium batteries to overcharge and burst.
A shunt circuit could be made that monitors the cell voltage and triggers a bypass resistor once the cell reaches 4.0 volts. That would probably also trick the NiMH charger to think a voltage delta event has happened, because NiMH batteries change their resistance when full, which signals a smart charger that the battery is done.
Dax: LiFePO4 battery CV charging voltage is 3.6V. You could use a LDO
set to 3.6V in series or use a proper LiFe charger chip.
Manuka: Yeah. I use LiFePO battery with my (old) Fujifilm camera that
seems to run into a lot of issues with NiMH as I found out that its
undervoltage detection at 2.5V (drift?). I am very happy with these
batteries for my camera. I have a NiMH that was dead shorted and it
makes a good dummy cell.
I’ve grown fond of the nickle-zinc rechargeables.
They have a higher OCV when fresh charged.
BUT you have to watch out for the “knee voltage” curve being in a new place.
None of my cameras are calibrated for this
and the camera will not know that the cells
are about to go over the cliff
and shut the camera down.
….. corrupt or lost files are no fun :(
So you have to keep a close eye
on the battery indicator.
as the mid point bar is actually the low reading now.
The upside is better performance while the cells are fresh.
better flash recovery and slightly faster auto-focus.
downside: My Panasonic looses it’s auto-focus
first, when the cells are low.
They’re also handy for making cheap flashlights brighter too.
But I don’t know how much it affects the longevity of them though.
Amazing! The best use of CHDK till date.I am sure this will open up many more possibilities.
That is really cool
that trasmitter has a range of only 500m.. please explain why are you using this to send images from the stratosphere
It’s line of sight. If you put a transmitter up really, really high, you can get a very good range out of it.
Proper antennas help as well.
Yea, I’ve decoded SSDV data from flights over 500km away, once they get to a high enough altitude to get over the horizon. It still amazes me that I can hear a 10mw transmitter that distance away, let alone decode images transmitted with it. The record for decoding telemetry from one of these modules is 800km!
Entertained how it’s called “video” but it is not. It is sending a sequence of photos.
We have transmitted small video clips from payloads using this system, though it was very tiny and definitely not real time :)