Help for FEZ Cerb40 II with RF433 Module

but your other thread also talked about this power bank not being reliable.

Sorry, I don’t want to sound harsh, but I’m just going to say this. This really seems like something that I think you are having problems outside the Cerb40, and while I hear your frustration I suspect that you’re blaming the wrong part of the solution.

As I also stated in another thread, power banks for charging mobile phones are not a good solution if your current drawn is not constant. At low currents they tend to switch off and cause unpredictable issues.

I would suggest you look at the Seeed Studio LipoRider Pro and either a 6000mA or 3000mA battery to go with it. This module does not switch off the output based on current. It will provide power as long as the output is switched on.

Another factor is that the LipoRider Pro is a power path design so it can power your device at the same time as charging the battery. Power banks for mobile phones do not (at least the ones I have seen) as they are limited to either 1000mA or 500mA of current on the input.

I know the power banks are cheap but you have learned a valuable lesson about this :slight_smile:

"but your other thread also talked about this power bank not being reliable"
So I change many power banks to check it.
I changes many to check (different board, power,RF …), like I said before, the other boards works well with the RF Module.
I am not blaming to cerrb, I just don’t know how to solve it.
I blaming to my Inability.
Ok, keep debugging…

What happens if you use a 1 or 2 amp power supply instead of the power bank?

Does it then work ok?

Test :
I use Cerb with power bank and connect TX send data to FEZ Cerbuino Bee’s RX,
Works fine.
the code on Cerb is the same in RF module case.
So ,it means the power bank is ok?

How much is the output current from Cerb’s 3.3V pin?
I use this pin to power the RF module.

Thanks Dave, I do not have 2 amp power supply and I will find a LipoRider Pro for testing.

I think you are trying to simplify things when they’re not simple. Power isn’t just as simple as saying “how much output current is from cerb’s 3v3 pin”. If you connect the cerb to a 5v 200ma supply, then the limit will be probably be the input source. If you connect to a 1a or 2a supply, then the limit might then move to be the on-board regulator.

So you said earlier that the current draw (from spec sheet I assume?) is up to 100ma. The expected regulation capacity of the reg on board the cerb40 mk2 is 800ma, so if your current draw is only 100ma then the reg should handle that and the cerb40, if that’s all you have running.

Personally I’d try a phone charger (a modern one will supply regulated 5v usually at around 1a for fast charging) as your power source to see if that behaves acceptably, that should give you plenty of headroom before you approach the limits of the power supply.

The other thing I’d suggest longer term if you don’t have decent current measuring (tools or experience or capability) is getting one of these and potentially the OLED backpack. Simple way to connect a meter and see what current draw is, or with the OLED you can just see the draw on screen over time. That may help you see if the RF module is actually drawing more than it’s meant to. I have had one for a few weeks and it’s easy to use and helpful to this kind of problem.

Thank you Brett.

This product is sold out! (23 waiting)… I will join to waiting. Thanks.

I measured my Cerb40 (no app, just standard out of the packet firmware) and current consumption was ~51mA. Not much variation I could see at start up or anything. So add that to the 100mA of your RF and you should still be under 200mA.

Did you ever point out the RF433 module datasheet to us?

Thank you Brett.
Please find here.分享/RD232-H_Wireless_Modem_500mW_Data_Sheet_E.pdf

Which model do you have? This one is the one that has 600mA maximum current draw at 5v as well… so certainly your 800mA regulator will struggle catering for that load, and since the load looks to be somewhat peaky (34mA - 40mA typical read mode, then out to 600mA transmitting) I would also suggest that you need to consider the power carefully.

If I was you I’d look at making/buying a decent switchmode regulator to power both the cerb40 and the radio and including some extra capacitance on the power input to the radio.

Thank you Brett and andre.m
my module is TTL Interface

for decent switchmode regulator , any recommendation?
and How much capacity of the cap should be used?

thank you for your help , I appreciate.

How about

How about something like one of these