Sensebender Micro

Fabien

I have a batch of 5 sensebender and actually I build 3 and one of them doesn't work properly. Lot of st:fail when I put my finger on the board it works better so I try to make all solder one more time but it's not ok. I try with few radios and same radios work well on the others sensbender.
Any idea or way to exchange with Itead ?

tbowmo

@Fabien

Where exactly do you put your finger on it, in order to get it working?

tbowmo

@gloob

It's the same power rail (FTDI, and the battery connector). What do you supply the board with, thru the FTDI header?

Fabien

@tbowmo difficult to answer this question. It seems to be on Atmega but after trying to resold it's not better. I resol capacitors, resistors ... I don't know what to do now ...

tbowmo

@Fabien

Did you also resolder the atmega itself?

Could you try and measure supply current it uses?

Fabien

current when powering on : 20 mA and during sleeping about 20uA (not very accurate).

tbowmo

@Fabien

Have you tried to add an extra capacitor to the NRF module, on the one that's bad? (Could be your finger adds a bit more capacitance, I know it's a wild guess but just trying to think out loud)

Fabien

Ok but wich value ? I just finish to solder my 4th sensebender and ok too.

hek

Does the failed messages reach their destination (gateway in your case)? As you might know it is the ack that never reaches the sensbender node which could be a result of power issues on the gateway side.

Fabien

no, message are not recieve. I find someting :
When I touch the NRF24 antenna (just a little it sifficient), it works. fine.
Strange, same radio on other sensebender doesn't need this and other radio on this sensebender need to bo "touch".
I try with 10uF additionnal on NRF but no change ...

hek

Do you use a socket or is the NRF module directly soldered onto the sensbender?

(a bad connection in socket could be a problem... and when you press NRF module it has connection again)

Fabien

Yes it's directly sold (and very hard to change with metallised hole). I will give a last try with another radio ...

Fabien

Ok end of story ... sensebender card is dead ! 2 metallized hole were destroy by solder/unsoldering NRF modules.
Hope my last Sensebender will work. And if there is a batch with light version I will reuse T/H sensor

gloob

@Fabien it seems that you have the same problem as me. I ordered a new set of radio modules to test if it is the fault of the radios. I will give feedback here about my progress.

I aleady tried to add capacitors on the radio module but this did not help.
There is also no difference if I power the micro from the FTDI or the battery connector.

tbowmo

@Fabien

Unfortunately I don't think there will be a light edition coming out at the moment. Currently the savings is way too small (I'm estimating a savings of 4-5$ compared to the full sensebender edition).

hek

@Fabien

Here are some quite nice repair guides
http://www.circuitrework.com/guides/guides.shtml

More specifically
http://www.circuitrework.com/guides/5-1.shtml

Fabien

@gloob it's not a radio problem. Same radio works on the others boards.
@hek I will try to repair the board ...

mvader

looking for some help programming this thing.
I had a pl2303 usb programmer, but it had no DTR, so i orders a new usb programmer
this one is a cp2102 with a DTR line.
but still the same problem. it never uploads the code.
i have the right board, processor and port chosen.
i have tried all the programmers in the IDE but none work.
it just says "uploading" and then eventually errors out.
any suggestions?

EDIT: nm i read something about switching tx and rx and i figured what the heck and surprise it worked..
sketch uploaded..

tlund

Hi @tbowmo

Thanks for bringing this great project to the community.

I'm trying to understand the sensebender's power profile, especially the sleep current.

I have previously done some measurements with the atmega328p (pro mini) + NRF. In addition to that I have also looked at the datasheets for the other components on the sensebender.

It seems the theoretical low sleep current consumption is something like this:

* nrf24l01+    900nA
* atmega328p     5uA (with WD)
* si7021        60nA
* atsha204      30nA
* at23df512c   300nA
  =  Total     6.3uA

The SBMicro seems to draw ~50uA in sleep mode with the default configuration.

I managed to put the flash memory into "ultra deep sleep"(*), causing the total consumption to drop to ~27uA. So there is still around 20uA that is not accounted for.

I've also tried putting the atsha204 into sleep, but that did not make any difference (also confirmed by the specs).

Are there some other settings/sleep modes that have not been enabled yet? What about the atmega itself?

Do any of you have the a sensebender prototype with separate components, and can test sleep current by removing components one
by one? (Before I start cutting traces on my own sensebenders in order to zero in on the target component).

Is there something I'm missing?

Datasheets:
ATSHA204
AT25DF512C
Si7021 A20

(*) in setup(): flash.initialize(); flash.ultra_deep_sleep() <- From datasheet

tbowmo

@tlund

Interesting figures.. are you sure that you've got a genuine nrf24 chip on the radio? Could be a fake with higher power consumption.

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