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Topic: Do I need a "baseboard" for an HC-05 Bluetooth module? (Read 184 times) previous topic - next topic

beetree

Sorry if it's easy to find, but I've spent a long time  looking.
I can buy an HC05 with legs, or legless .
I assume the legless ones solder straight on to the baseboard.
Apart from an LED, why would I want the baseboard?
I understand there's a requirement for 3.3V where many folk just use 5v, but I can arrange a couple of resistors.

Thanks

B

ieee488

I haven't seen the HC05 modules without the connector pins.
Though to be fair I haven't been looking to buy any.
Can you link to the ones you are seeing?



beetree

There are loads of ebay sellers selling one or the other.
This listing has both:

192562341621

as does
272441022023

There's little between the prices in these (maybe the same seller) listings, but some far eastern sellers have the legless boards, or "6 pin " boards for much less.


(Then there are JY-MCU modules 223017819054 which look similar but "Bluetooth adapter is not included". Huh?
And what the "Bee"s are I have no idea. :smiley-confuse: )

Nick_Pyner

#3
Aug 13, 2018, 02:10 am Last Edit: Aug 13, 2018, 02:10 am by Nick_Pyner
I can buy an HC05 with legs, or legless .
I bet you haven't got a good reason for buying them legless, so don't.

The only good reason for getting a legless that I can think of is when you are making a custom PCB with all 3.3v devices.  If that is what you are doing, I'm sure you wouldn't be asking.

The main reason for selling legless modules is that they go on blank backboards that suckers bought because they thought they were on a good deal. Yes, it does happen.

The main reason for selling blank backboards is that there will always be a sucker to buy them.

beetree

OK, well baseboardless, is the question then- ! What's on the "baseboard"?
You're saying   just a 3.3v regulator ?

If you look at the listings I cited, there are 2 slightly different baseboards. There's a button on one but not the other, but they both have a SOT23 3 pin so that's the Vreg I guess.

But eg a Uno already has 3.3V right? So why do people mess with 2 resistors to make it? (Use a  pretty blue led?)

CrossRoads

Uno only has 150mA of 3.3V current. If you need more, the baseboard can provide that with it's own 3.3V regulator from a 5V source.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Nick_Pyner

OK, well baseboardless, is the question then- ! What's on the "baseboard"?
You're saying   just a 3.3v regulator ?

If you look at the listings I cited, there are 2 slightly different baseboards. There's a button on one but not the other, but they both have a SOT23 3 pin so that's the Vreg I guess.

But eg a Uno already has 3.3V right? So why do people mess with 2 resistors to make it? (Use a  pretty blue led?)

What's on the baseboard is the regulator, a status LED, and a lot less fartarsing around with a soldering iron against non-standard PCB pads. The button is for configuration - convenient but not essential. I understand you can still use the KEY pin even if you have the button. It's not a good idea to use the Uno's 3.3v pin for this. I don't think Crossroads is right and Uno is only good for 50mA. I think Bluetooth needs about 40mA.

beetree

Nick there are non-backboard boards with pins, though at least some are the Jy-Mcu(?) things.

So assuming one uses a 3V3 supply , there's still the RX level which would be wrong?

I see at least one guy selling a board to deal with that ( 2 R's). Wouldn't be too hard to put two SMDs on a backboard, perhaps some do. Some of them appear to have different part counts.

Looks like the Uno 3.3V is regulated by a LP2985, max  150mA

Nick_Pyner

#8
Aug 13, 2018, 04:54 pm Last Edit: Aug 13, 2018, 05:03 pm by Nick_Pyner
Nick there are non-backboard boards with pins, though at least some are the Jy-Mcu(?) things.
This is incoherent.
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So assuming one uses a 3V3 supply , there's still the RX level which would be wrong?
Read the back of the board to assess whether using 3.3v is a good idea. There are HC-06s on 3.3v boards and HC-05s on  dual voltage boards. And yes, you should still feed Rx with 3.3v.
Quote
Wouldn't be too hard to put two SMDs on a backboard, perhaps some do. Some of them appear to have different part counts.
If you want to go down that path, you are a better man than I. Mere mortals are more inclined to put the board and resistors on a shield, which is what the commercials do as well. You can get HC-05 with downwards pins thereby more suitable for this.
Quote
Looks like the Uno 3.3V is regulated by a LP2985, max  150mA
I'm afraid that means nothing to me, but this   https://store.arduino.cc/usa/arduino-unos -rev3   does. Maybe there have been changes, but it's meaningless anyway. Nobody, but nobody, runs HC-0x off the Uno 3.3v pin, principally because it is a really dumb idea.

beetree

What's "incoherent", other than life, and all that? :D

Yes a lot of boards say power up to 6v but signal 3.3v.


SO, does anyone who uses them, know the score?

Is "everyone" ignoring the 3.3V signal bit?
That's what the guy who makes the board with 2 resistors says. ( ebay 223065968822) It costs nearly as much as an HC-05, and I'll need a number, to be given away.


A couple of 1206 by hand is ok, if there's somewhere to put them. I used to do smaller when I didn't need glasses...  But it can't be the proper answer.


Can't make your link work, but yes, found quote of 50mA of 3V3, regulator capable of more. Same as the HC05 max - so not as dumb as using the wrong signal level.

Nick_Pyner

Yes a lot of boards say power up to 6v but signal 3.3v.
And they say down to 3.6v, with a clear implication that, if you feed it 3.3v, you deserve all the grief you get. And you won't be the first.
Quote
SO, does anyone who uses them, know the score?

Is "everyone" ignoring the 3.3V signal bit?
That's what the guy who makes the board with 2 resistors says.
He's wrong. Using a divider is common practice but Google Images shows about 50% of pictures have no divider.  I didn't use one for years because I didn't realise I should, and yes it was written on the back. I have never heard of anybody killing a board because of this, but only an idiot would say don't bother with the divider.
Quote
Can't make your link work, but yes, found quote of 50mA of 3V3, regulator capable of more. Same as the HC05 max - so not as dumb as using the wrong signal level.
I'm not sure why you are flogging this horse, maybe it is just an intellectual exercise, but I can't help feel that you have not actually held a bare HC-05 in your hand.

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