HC-05 VERSION:4.0-20190815 datasheet ??

Has someone a HC-05 VERSION:4.0 datasheet?

AT+INIT --> Init SPP profile mode does't works and return an ERROR:[0] !!!!

Usualy i use HC-05 VERSION:2.0 without problems and probably 4.0 version has different behaviour, but i have not found documentation.


It may mean that the profile is already loaded, which would hardly be surprising. Also, I understand that the more obscure commands are not accessible by merely pushing the button, and you need to apply power to the EN pin. There may be something to this effect on the Martyn Currey website.

i have been powered EN pin (34) to high level for program mode.

HC-05 v4 execute commands like AT+NAME=xxxxx or AT+ROLE=1 and AT+CMODE=0, but not AT+INIT.
Another detail is that EN pin (34) need to a higher voltage level, 3.3 is too LOW.

I need to a datasheet V4.00,all Martyn Currey posts talks about 2.0 version.

Another thing I don't understand is ERROR:[0], if i'm not mistaken is a syntax error.


I'm not sure there is such a thing as an HC-05 v4 and, if there was, I'm pretty sure Currey would know about it. I alluded to his site because he refers to the more obscure commands for HC-05, and I have never heard of the INIT command. He also has information about BT4. This may be merely a matter of nomenclature, and I think you need to be more forthcoming about what you are actually holding in your hand. Counting the black LSI chips on the board might be a good place to start.

thanks for your concern,in this post subject i attached real AT+VERSION response of my HC-05.
VERSION:4.0-20190815 was the response and that is the difference with my other BT devices.

Now is 02:36 AM in Italy and i'm tired.This situation is not critical for me because i have been understood the reason and i can buy only HC-05 V2 versions,but i'd like to understand the V4 version.

Tomorrow i'll try to send a message to Currey.


AT+VERSION response of my HC-05.
VERSION:4.0-20190815 was the response

OK, well, that proves my concerns were unfounded..........

And it's a nice sunny afternoon here in Australia.

I bought such modules in China.
HC-05 VERSION: 4.0-20190815. It's a fake copy.
AT + SENM = 2,3 ERROR: [0]
A memory chip is installed for decoration. This is a relabeled other chip. Having removed it, I did not affect the operation of the module and found that all contact pads were closed.
Discard 60 modules.

Hi everyone.

I’m having the same problem, I have version 4.0-20190815 and two things, first the command BIND doesn’t allow me to pair it with a specific MAC I want to make an interaction between master and slave, and second is that when I set up a slave, I reconnect it and it is blinking slow like if it was on AT mode instead of searching mode(Fast blinking) I would be grateful if someone has the datasheet of different AT commands for this version. Thanks

It seems like your answer lies in reply#6.

I have the same problem with this version. I can change name and password but it's not available change UART. Always is 4800.
Characters when is receiving are fake.
Connecting is very difficult and disconnecting itself few seconds later.

The chinesse provider doesn't help.

Any idea?

Any idea?

Ditch it and get a v2.

hello and i'm the winner of this VERSION:4.0-20190815

i used HC05 with arduino nano and till this time i used STATE PIN with POLAR 1,0 that allow me to RESET arduino PIN by a rising forehead. With this version i can't do this.

Someone help me to correct this ? can i downgrade the firmware or doing something to have this rising forehead on my arduino RESET pin


Your post is incoherent, but the answer is probably "no" to everything. Reading reply #6 is a good place to start, then reply #9. Do not read replay #5.

I friends, i'm not Mister Wolf but i solved problem.
I don't know if all HC-05 with VERSION:4.0-20190815 has the same behavior but that's all!!!

Key(program mode) pin have a low value ,under 3.3 when connected with pin 34 so i used a different voltage regolator (5k resistor in serial with 22k resistor).

BT VERSION:4.0-20190815 needs too much current so if you test it with USB PC port is possible that you can't pair or find devices.Use a battery with common ground with usb to serial key.

before i used it :


now i use


with this command i can find my device using only AT+CMODE=0 and AT+ROLE=1 before AT+RNAME.

for now i'm testing it only with terminal server , when i'll use code and my pcboard i'll update this post.