yet another HC-05 issue(sorry)

We have only just recently ventured into the world of Arduino so please forgive us if we are a little dumb..

we bought the HC-05 module from here https://www.aliexpress.com/item/4-0-Bluetooth-module-ble-serial-BLE-CC2540-CC2541-Bluetooth-module-with-bottom-plate-iBeacon-module/32476367379.html?spm=2114.13010608.0.0.c9sJAo

And have tried everything to get it working.... tried almost every guide that we could find with no joy..

We cannot enter AT command mode and connecting via Bluetooth terminal on our android devices just gives us failed to connect,,

PLEASE could some one help..

We wish to use these to allow are kids to build some Nano based battlebots and control them via their tablets..

regards
Ebam

If you connected the module to a 5V Arduino without level shifters, it may have been destroyed.

Otherwise, for informed help read the post "How to use this forum" and follow the directions.

level shifters?????????????????

so many projects out there very few mentioned "level shifters"

Used this for example http://www.instructables.com/id/Remotely-Control-LED-using-HC-05-Bluetooth-Arduino/

and many others very similar.

PLEASE explain!

Your module has 3.3V data lines. If you connect those data lines directly to a 5V Arduino, the module will be destroyed. Use a level shifter instead.

Yes, there is lots and lots of bad advice on the internet, and Instructables has some of the worst possible advice.

hmmmmmm that includes this forum too as tried several projects (including AT command ones) here that did not mention level shifters and showed wiring up as I had done!... and that also includes project hub

Also why can I not just connect to the 3.3v pin or is that different to what you are refering too???

Plus was using Nano before using uno which only has the 3.3v!!!!!!!!!!!

And also why can my Android devices see it yet cannot connect?????

finally WHAT project would you recommend for testing purposes???

Please take a few moments and educate yourself about level shifters.

yep that made COMPLETE sense why this would happen!!!!!! and why it would have been fried/damaged when connecting to a nano...

Also explained why when using AT commands most projects never mentioned level shifters and mentioned using both 3.3v and 5v pins!!!!

jremington:
Your module has 3.3V data lines. If you connect those data lines directly to a 5V Arduino, the module will be destroyed. Use a level shifter instead.

Yes, there is lots and lots of bad advice on the internet, and Instructables has some of the worst possible advice.

could you please explain why this CARMAGEDDON: The Agile Arduino Car - Arduino Project Hub does not require a level shifter please??????????

Or would someone else explain why?

To clear away any misunderstanding.....

  1. Your device is not an HC-05, it is an HM-10.

  2. If the tablets you intend to use are Android, you should check that they are Bluetooth-4 devices and thereby compatible with the HM-10. Most modern ones are but, if they are not, you should use an HC-05. If they are Apple, they will be kosher but you had better check that it is a practical proposition to use them.

  3. The reason why you never see mention of level shifters is that, while the bluetooth module is a 3.3v device, you don't need to mess about with them, and a simple 1k/2k voltage divider between Arduino Tx and bluetooth Rx is all that is needed. Failure to do this does not mean certain death, but it is good practice.

a simple 1k/2k voltage divider between Arduino Tx and bluetooth Rx is all that is needed

In other words, a level shifter.

so that still fails to explain why SOOOOOOOOOOOOOOOOOOOOOOOOO many projects NEVER show level shifters..

Anyway can some point me in the direction of a good Bluetooth module/level shift wiring chart/diagram please???

many projects NEVER show level shifters

This is because most people who post don't understand what they are doing. "Instructables" is one of the worst of the offenders.

Sometimes a 3.3V circuit will survive being connected to a 5V circuit for a while, so people post about their success and leave you to learn your lesson later.

You might find the following background notes useful

http://homepages.ihug.com.au/~npyner/Arduino/GUIDE_2BT.pdf
http://homepages.ihug.com.au/~npyner/Arduino/BT_2_WAY.ino

It is true that, in Google images, about half of them show a straight connection Arduino Tx>bluetooth Rx. If you've done that, don't panic. I ran one continuously for some years that way, but it is still bad practice.

Thank you both for all you assistance's... I appreciate it very much indeed.. Off to go play and then to find a 3d printable Matilda (robot wars) as partner wants to build one(well she wants me too for her) she wants to use phone and BT hence the questions

Again Thank you

"Matilda", do you mean the British WW2 heavy tank? Just curious.

My roommate and I built an Arduino RC Panzer IV F2 (3D printed) this past semester. I love WW2 tanks.

Power_Broker:
"Matilda", do you mean the British WW2 heavy tank? Just curious.

My roommate and I built an Arduino RC Panzer IV F2 (3D printed) this past semester. I love WW2 tanks.

No sorry the robot wars matilda partner is a huge fan .

As to WW2 Tank heck another nutter like me!!!!!!!!!!

Do you have the links etc for pz2?? Dang would love to give that a wurl!!

THIS IS WHY I GET CONFUSED ABOUT THE SHIFTER

And thats on the Arduino create site.

Have 4 modules and NONE CONNECT to my tablet or phone they all see the modules and they are all have Bluetooth 4!!!!

ebam2014:
THIS IS WHY I GET CONFUSED ABOUT THE SHIFTER

Arduino Bluetooth Basic Tutorial - Arduino Project Hub

And thats on the Arduino create site.

Have 4 modules and NONE CONNECT to my tablet or phone they all see the modules and they are all have Bluetooth 4!!!!

As mentioned by others earlier, 1) your module is an HM-10 NOT an HC-05 and 2) just because some tutorial online doesn't use a level shifter doesn't mean you shouldn't

Panzer Link. There's a pic and a video. The video isn't the greatest, it's my roommate driving the tank around our room, but it shows most of the cool features we put in.

Power_Broker:
As mentioned by others earlier, 1) your module is an HM-10 NOT an HC-05 and 2) just because some tutorial online doesn't use a level shifter doesn't mean you shouldn't

Panzer Link. There's a pic and a video. The video isn't the greatest, it's my roommate driving the tank around our room, but it shows most of the cool features we put in.

ok so why does the HM-10 not work? What are the differencea?

Thank you for the link anychance of the files etc?

ebam2014:
ok so why does the HM-10 not work? What are the differencea?

Please read the documentation on this website very carefully. Don't worry too much about the difference between the HM-10 and the HC-05, just focus on how to use YOUR module. The website will tell you everything you need to know about HM-10 modules including an example sketch. Also, it looks like there is a built-in level shifter for the HM-10 module, so you are good to go by directly connecting it to your Arduino pins! See below:

The basic HM-10 module (and the two TI chips it is based on) works at 3.3V so it cannot be directly connected to a 5V microcontroller (e.g. Arduino). However the HM-10 breakout boards integrate voltage (DC-DC) and logic level converters (LLC) so that their pins can be directly wired to an Arduino.

ebam2014:
Thank you for the link anychance of the files etc?

Check here again. I added lots of stuff. I will eventually add the 3D model and schematics, but not for a while.