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Old Jan 18, 2013, 12:47 PM
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23.8.1. Smart Reset
The EZRadioPRO transceiver contains an enhanced integrated SMART RESET or POR circuit. The POR circuit contains both a classic level threshold reset as well as a slope detector POR. This reset circuit was designed to produce a reliable reset signal under any circumstances. Reset will be initiated if any of the following conditions occur:

- Initial power on, VDD starts from gnd: reset is active till VDD reaches VRR (see table);
- When VDD decreases below VLD for any reason: reset is active till VDD reaches VRR;
- A software reset via “Register 08h. Operating Mode and Function Control 2”: reset is active for time TSWRST
- On the rising edge of a VDD glitch when the supply voltage exceeds the following time functioned limit.

The reset will initialize all registers to their default values. The reset signal is also available for output and use by the microcontroller by using the default setting for GPIO_0. The inverted reset signal is available by default on GPIO_1.
I'd love to hear any details you can give on problems with the "smart reset".

It doesn't sound like that bad of a feature. Sounds like it's only supposed to activate with power supply problems. It's probably better to reset and regain the link than risk having all your registers corrupted and the chip hung.

Sounds like a problem that will go away with a better design. Not worrying as much about size or component cost should make it easy to create a more robust power supply, a couple more/bigger caps sounds like an easy answer. It also has to be that amp that's causing switching noise or brownouts in the power supply, I've never heard of any problems like this on the unamplified modules.
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Old Jan 18, 2013, 02:50 PM
Stuart
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Originally Posted by jakestew View Post
I'd love to hear any details you can give on problems with the "smart reset".
See post #53.

The 'smart reset' is just way too sensitive to normal power supply glitches in my view, and I doubt the figures in the datasheet.

You should have the choice of using it or not.

I never had a problem, ever, with the controlling micro crashing, so why should the Si4432 need such sensitive protection ?
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Old Jan 18, 2013, 04:55 PM
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since you have to re-init anyway i dont see the point. if the registers came up in a useful state it might help but i never see that happen on any of these transceiver chips. . with such excellent bod and wdt features on modern micros it just seems less important. and with the super quick status checking on those silabs chips it should be easy to restart when things go astray.
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Old Jan 19, 2013, 11:39 PM
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I think it's just a weak design by HopeRF. All the SiLabs chips have the same "smart reset" feature, and the 22BP is the only design I've heard of having this problem. My pair of 3DR (HM-TRP module based) don't have the problem.

In any case, it should be easily solved with proper design. I'd rather have the feature and have to use a little bigger, or a few more, caps. than have to always worry that my registers might be all screwed up without knowing about it.

I thought I might put up some of the files I'm looking at, but some links to start with I guess...

Here's the only eagle files I've found for OpenLRS...
http://diydrones.com/profiles/blogs/...ource=activity

Some design files and info for the SiLabs + RFMD amp can be found here...
http://www.digikey.com/product-detai...-EK-ND/3457960

More info on the standard SiLabs reference designs for their EZradioPro and MCU+radio chips can be found on their site. The info is a bit scattered, but if you look at the test cards that plug into their dev board you can find quite a few different designs. Their 100mW designs need to have either two antennas or a RF switch.
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Old Jan 20, 2013, 03:39 AM
Stuart
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Originally Posted by jakestew View Post
I think it's just a weak design by HopeRF. All the SiLabs chips have the same "smart reset" feature, and the 22BP is the only design I've heard of having this problem.
Nothing Hope could do about it, is there ? As you say its inherrent in the design of the Si4332.

Silicon Labs did build in the option to disable it, so they obviously did want to give users the option not to use it, but unfortunately its turned back on again by the Si4432 code every time TX is turned on, which is when the powerline glitches will occur. Possibly a very fast micro can turn it off straight after TXon before it has enough time to activate.

In a fast running setup you would presumably setting an interrupt to detect transmission (of a packet) finished, or checking the status registers, so at a very minimum you need to check the POR status at the same time.

As this is a 'feature' built in to the Si4432 itself, the potential for a problem in any module using it wont go away just because you have not seen it.
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Old Jan 21, 2013, 02:27 PM
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I don't see it as a problem. It looks to me like HopeRF didn't design their module right. In a mission critical application like RC control and telemetry you can't just hope and pray your power supply is good enough and your registers aren't corrupted by power supply problems. The smart reset is telling you that your power supply to the Si4432 is crap. Better to figure that out right away than suffer constant, random register corruption that you have no way to detect.

Complicated code mechanisms to try to work around a "feature" is a big PITA. It should be WAY easier to just fix the problem in the first place. 5 minutes with a soldering iron is way better than 5 hours of coding (that just patches over the problem) IMHO.

If I'm understanding it right then the power supply glitch is happening when their class C amp kicks in. That's just poor design. They should have a big enough cap across the power rail on that amp chip so that it doesn't brown out or send power spikes to the Si4432 and cause a smart reset.

There's no reason to blame the Si4432. Every chip out there has certain power supply requirements. They usually specify a voltage range, power draw, and a maximum amount of power supply ripple. That amp is causing either a big ripple that sets off the smart reset, or it's browning out the whole circuit when it turns on.

If you get a chance throw a scope on the power rails at various points in the module. It sounds like this is a simple dirty power problem and should be easy to fix. Battery power is the cleanest power supply you can get, so any glitches must be introduced by the electrical design that is hooked up to them. You might also try some caps or filtering on the module supply, maybe even an external cap will be enough to fix the problem.

Your input has been very helpful. It's good to figure out now that the class C amp is not going to give good power level control, and that we need to pay good attention to power supply issues.

I think a scratch built design is the way to go. There's only around 20 or so components in the reference designs. Adding an Atmel 328 might add another 10. 30 components shouldn't be terribly difficult to do for the average DIYer.

I'm curious what size components people are comfortable with. I've been using 1200 size lately, but think 600-800 size shouldn't be too hard to deal with.

Here's a size chart for SMT components...
http://www.niccomp.com/help/files/SMTSize0901.pdf

The HopeRF and most modern Chinese stuff uses 402 size stuff, which is grain of sand sized to my eyes. 603 is about the size of a grain of rice, 805 is fatter like two grains of rice stuck together. 1206 is pretty comfortable to work with, but it's sometimes hard to find all the values you need in that size, or they cost more, or you have to buy 1000 of them.

In any case, no module really fits the bill. And if we're going to be building a board anyways I figure we might as well do the whole thing. With the handful of reference designs out there it really shouldn't be too hard to get the circuit design right.
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Old Jan 21, 2013, 04:55 PM
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0402 i use and workout well (only build 1/2 so if it takes longer fair enough) but 0603 would suit most
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Old Jan 22, 2013, 01:45 PM
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You're much braver than I!

Any design has to be simple enough for the end users to make. The toughest part will be the SiLabs chips. This might work well as a kit type project with the board and tough SMT work already done and just the larger SMT, or even a few PTH components, for the user to solder.

I can't help but keep thinking about using the Si1000. It would probably only save about a dollar or two, but it would be one less chip and save board space. The problem is that I've never done any 8051 programming and there aren't as many code examples out there. The 3DR telemetry radio code is there, but doesn't do any of the RC part. The OpenLRS code does pretty much everything, but runs on the Atmel chip.

It will have to come down to how many people want to try 8051 programming vs. how many are willing to contribute with an Atmel based project.

Seems like every project I've done requires learning a new processor or new programming language. I can't help but think that eventually that will turn out to bite me in the ass and I'll get completely stuck on something.
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Old Jan 22, 2013, 01:53 PM
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then maybe time to stop jumping around to different processors. i tried nearly all of them and finally settled on avr for the very reasons you mention.

btw my favorite smd pkg is 0201 and i use a 2 lb soldering iron heated over gas burner. you know... like use to make tin cups. lol!
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Old Jan 22, 2013, 02:27 PM
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why do a part kit? Can people only half solder
Full kit or built, if you can't solder why would you even try with something like this.
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Old Jan 22, 2013, 02:28 PM
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Originally Posted by dave1993 View Post
then maybe time to stop jumping around to different processors. i tried nearly all of them and finally settled on avr for the very reasons you mention.

btw my favorite smd pkg is 0201 and i use a 2 lb soldering iron heated over gas burner. you know... like use to make tin cups. lol!

hmmm that could work!! Use solder paste so yeah would do the job
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Old Jan 22, 2013, 02:38 PM
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why do a part kit? Can people only half solder
Full kit or built, if you can't solder why would you even try with something like this.
I think we'd be operating under the FCC's homebuilt rule, which only requires that you attempt to design according to the rules, but don't have to have actual tests and certification.

The FCC allows only 5 units and they can't be created for resale. That means that people are going to have to build these for themselves.

Just because you can't solder a 0402 doesn't mean you can't solder PTH or larger SMT sizes. Larger sizes can be done with an iron, but smaller sizes are best done with hot air.
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Old Jan 22, 2013, 02:47 PM
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that said you could just leave off leaded part and its a kit! As ESC32 do to get around rules

bte you'd be shocked how easy solder paste works with soldering iron
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Old Jan 23, 2013, 08:09 AM
Stuart
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Originally Posted by jakestew View Post
If you get a chance throw a scope on the power rails at various points in the module. It sounds like this is a simple dirty power problem and should be easy to fix.
Scope ?

Looked it up on Google.

Think I may have one of them on my bench, thought it was just a small TV. Always wondered why I could not get a decent (any really) picture on it, and why it has so many knobs and buttons.
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Old Jan 23, 2013, 08:18 AM
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Well there is the issue, for a product to be popular, and to have lots of good contributors to the code, it needs to use a Micro that a lot of other people use.

It also needs to be relatively easy to assemble. I guess there are a lot of people who think they may just be able to assemble SMT in 0603 and QFN packages, but I doubt many can do it well enough to succeed or produce a reliable and safe finished article. 1206/0805 and SOIC is likely OK, tweezers and a very pointy soldering iron bit is enough.

So you may be faced with the prospect of at least making an RF module (aka RFM22 lookalike). A module is not a finished product mind, it needs other bits to make it do anything, so not may be subject to the same certification regime.

Even so to make and sell such a module in the EU, you would need to use lead free solder (yuk).
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