HM-10 (and HM-11) BLE – the good, the clones, and the down-right fake!

The HM-10 and HM-11 modules, originated by Jinan Huamao Technology look quite useful for tinkering about with Bluetooth, and their documentation is better than average and there is supplementary information on the web (e.g. Martyn Currey’s blog). The scourge of clones for this kind of module is not news to me but it turned out to be harder than I expected to get a satisfactory product from ebay or Aliexpress.

I would ideally like a genuine product, and while there are sellers proclaiming “genuine” in their listings, this often comes with an excessive price. Other than that, price seems to be a poor guide to quality. I consider a “clone” to be something which is functionally correct but not original and maybe with lower quality hardware. A module with the wrong firmware listed as “HM-10” is a fake, and if the core bluetooth chip (for these modules it is the Texas Instruments CC2541) is not correct it is a down-right fake. The last case is useless as it won’t be possible to load the HM-10 (or HM-11) firmware, which is available for download. Re-flashing is not particularly difficult, but generally involves some “hacky” soldering. Partially to alleviate the hassle of re-flashing but also to give me access to more of the CC2541’s pins (the HM-10 has lots of GPIO, ADCs, DS18B20, DHT11, and a poor-mans PWM), I designed some breakout boards and got a batch made. The Eagle CAD files are on GitHub, along with some links to software/instructions on reflashing.

It’s not that I wasn’t aware of the potential for fakery; I tried to assess listings by checking for ambiguous or garbled wording (almost universal!), clearly inaccurate descriptions, and checked the photos to see “CC2541” on the chip. I thought the most likely outcome was getting a module with an out-dated version of the hardware. I was wrong!

HM-10 Fail #1

On May 6th 2023, I bought two “HM-10” modules on breakouts from ebay seller Alimodule. The total price was £8.02, by no means the cheapest on sale. The breakout has a 5V regulator and [probably] some level shifting to allow it to be used on a 5V Arduino. I really wanted 3.3V supply and logic to work with an ESP8266, but I reckoned these would be OK to experiment with, and that I could butcher the breakout to achieve this. The downside of these boards is that they only expose the UART + status and key pins. The upside is that they are widely available.

After some stumbling about trying to follow the Huamao manual (and failing) it became clear that the firmware was wrong. THe device appears as “BT05” (which I later found out to imply some Bolutek firmware, although I never found documentation for it) and the result of AT+HELP shows the commands are wrong for HM-10.

I tried multiple times to flash new firmware, using both ESP8266 CCLoader and Raspberry Pi CC2541 programmer (see the GitHub link above) and got nowhere. The firmware appeared to upload correctly but the module appeared to be bricked. After SOME TIME, I realised that the chip id which is reported by the RPi programmer showed the chip was a CC2540, a TOTAL FAKE, even though the chip is clearly marked CC2541. Although these two chips are compatible at the source code level (I believe), they are not compatible at the level of compiled firmware. I tried REALLY HARD to find some firmware to run on the CC2540 but failed, so while the product which arrived would have worked as a simple serial-over-ble device, I now have junk!

I got a full refund, but no compensation for the lost time in working out I had a deliberate fake.

Avoid Alimodule!

HM-10 Fail #2

This time and for all the attempts below, I got “stamp” SMD modules to suit my shiney new breakout PCBs.

Ebay seller h-quality_electronic had a somewhat garbled description but a clear title – “HM-10 4.0 Bluetooth UART Transceiver Module Serial Port CC2541” – and a picture which looked OK; although it was missing one of the two SMD crystals (a common sign of a cost-reduced knock-off), the chip was right. I ordered 2 pieces for £6.80 delivered.

Unfortunately, it was the same story as before. The firmware claimed to be BT05 (and this was marked on the board) but many of the commands shown by executing AT+HELP simply returned “ERROR”. The chip id was read to disclose that this was another total fake with a CC2540 marked as CC2541. Seriously, someone went to the trouble of faking the markings on chips on a module only retailing for a few pounds!

This one ended with ebay customer support issuing me with a refund. Avoid this seller.

HM-10 Fail #3

Ebay seller cayin35 had a credible listing; it only mentioned CC2541, gave specific firmware versions, and the picture looked right. With only a few inconsistencies in the description I went for it: 2 items delivered for £6.82.

Sadly, the same story: crappy BT05 firmware with commands that don’t work and a chip which turned out to be a CC2540 when interrogated by a programmer. More TOTAL FAKERY.

A full refund again and another seller to avoid!

Now I am getting a bit pissed off. It really shouldn’t be this hard to get an item as it is described. This isn’t a matter of minor detail; these devices are NOT CC2541 and NOT HM-10.

HM-10 Success (partial)

Four boards from Aliexpress seller “Advanced Tech” cost me £12.91 including tax and postage. The description seemed mostly accurate for a HM-10, with the exception of chip ambiguity at the bottom of the description: “HM-10 CC2541 CC2540 4.0 Bluetooth UART Transceiver Module Transparent Serial Port”. I believe very early HM-10s did use the CC2540, which might explain how this comes about, but still. The picture did show a CC2541 and two SMD crystals (which is generally a sign of not cutting corners), so I gave it a shot.

These arrived today, August 10th 2023. It really has taken since May to cycle through order – wait – receive – test …

The hardware appears OK and the items received do look like the listing picture. The firmware advertises itself as HMSoft via a BLE scanner but once I started to interact with the device using AT commands it quickly became clear this is crap: AT+HELP? lists commands which dont all work (e.g. AT+VERSION returned nothing). AT+VERS? (which is the command used in a real HM-10) DID return a version string: “HMSoftV004”. Obviously nonsense. Firmware is a FAIL!

The Bluetooth chip is, however, a CC2541 (or at least it reports a chip id which matches, when queried by a programmer). And yes, miracle… I managed to flash it with a v540 firmware using the Raspberry Pi CC2541-programmer software. This isn’t the latest firmware but it is what I had in “.bin” form, and it supports updating over the serial interface using AT+SBLUP.

I’d have preferred not to have the hassle of a re-flash, but I’ll consider trying this seller in future as the evidence so far is that trying a new seller is more likely to waste my time and give me more junk than not.

HM-11 Fail

My first attempt to get some HM-11 was from ebay seller satisfyelectronics. Two items for £4.05 including tax and postage should maybe have alerted me to fakery but the title lacked the usual ambiguity about chip: “Bluetooth 4.0 module BLE CC2541 low power NEW HM-11 S“.

When the modules arrived it was immediately clear these were not HM-11 devices. The chip is not a Texas Instruments chip (CC254x)! By comparison with the Huamao datasheet and my HM-11 breakout boards it is obvious thath the module solder pads are all wrong. I should have spotted that in the photo. I can’t even test these and don’t know what they really are.

What egregious mis-description! I got a full refund.

Avoid satisfyelectronics!

HM-11 Success!

Aliexpress seller “fYD Open Source Hardware“. I bought 4 for £12.98 including tax and postage. The listing did give me some cause for concern as the title included “CC2540” (wrong!) and “CC2541”. The picture did show a CC2541 and two SMD crystals (which is generally a sign of not cutting corners), so I gave it a shot.

These were either genuine or good fakes. Hooray! The firmware was not the latest, being v6xx, but that is new enough to allow for firmware updating via the serial port using “AT+SBLUP” and the Huamao upload tool. The listing actually stated firmware v508.

I suppose there is no guarantee that they still have the same batch, and some of their other listings had garbled descriptions, but I would try them again.

Final Words

It is pretty clear that pictures and descriptions are not a good guide. If you find yourself in the same situation, make sure you check the chip id. If it is wrong demand a refund and avoid that seller.

Breakout Board for E18 Modules – DIY Zigbee at a Fraction of the Cost of an XBee

Having recently wanted to get my hands dirty with DIY Zigbee – see my other post on low cost DIY Zigbee – I couldn’t find any suitable breakout boards so, after having found the CC2530-based Ebyte E18-MS1 modules (which are rather economical and available from the manufacturer on Aliexpress… and seemingly without the curse of a glut of clones and fakes), I decided to make my own.

I wanted something quite simple but also flexible, with maximal scope for experimenting and learning. The main use case is to plug into breadboard but there was enough PCB space for some “convenience” components: two switches and three LEDs and associated resistors.

This is what it looked like once assembled (you can just see a BH1750 I2C light sensor on the rear):

Some notes on motivation, layout pragmatics, and options:

  • The long header is meant to be populated with right-angle pins. This will put the antenna nicely up and leaves plenty of space for other components on the breadboard (I find the breakouts with very wide dual-in-line pin-outs to be rather irritating, and Arduino style sockets and flying leads are not great when more than a few connections are to be made).
  • The 5 pin header is for firmware flashing. I opted for this, rather than the full 10 pin “debug” header which CCDebugger uses, for econonmy of space. These 5 pins are quite sufficient for using CCDebugger with TI SmartRF Flash Programmer (I made a little adapter) or if using something like Flash CC2531, which works fine for CC2530’s, (or my patched version for use with Pi v1 GPIOs).
  • The 4 pin header may be convenient for either UART or I2C connections. I’m expecting to be using PTVO and for the CC2530 it fixes UART pins to be P0.2 and P0.3. This header is meant to be mounted on the same side as the E18 module (opposite to switches).
    • The switches should be configured using the solder jumpers.
    • SJ1 handles the “Reset” button: A connects to E18 Reset; B connects to P0.0.
    • SJ2 handles the “Key” button: A connects to P0.1; B connects to P1.7 (which is used by the E18 factory firmware).
    • The on-board LEDs (and the enabling jumpers) visually correlate with the pins they are connected to: P0.4, P0.5, and P2.0.

Eagle design files are available on github but I am also currently (July 2023) selling surplus PCBs on ebay.

Creating Panelised PCBs in Eagle for Seeed Studio

After some misadventure and blind alleys I have an efficient and reliable approach to panelising PCBs in Eagle with v-scoring (v-cuts) to aid in board separation. I am using Eagle 9.6.2 (free version) and send PCBs to Seeed Studio.

The starting point is the Sparkfun-Panelizer ULP. Thanks for open-sourcing this, Sparkfun; I couldn’t have “got there” otherwise. Unfortunately, this completely bombed for me due to its failure to cope with space characters in file paths. This is easily fixed once diagnosed. Towards the end of the ULP, change the line which says sprintf(s, “SCRIPT %s;\n”, scriptFile); to say sprintf(s, “SCRIPT ‘%s’;\n”, scriptFile);. See that I added single quotation marks; what a difference two characters can make in progamming!

A second issue with the Sparkfun ULP is that component names get changed because the Eagle PASTE operation prevents name collision by assigning the next available number. The upshot is that each panelised board gets a different set of component names printed. Arghh! This does make sense if you think about these as being unique identifiers, as Eagle sees the whole composite as “one board”. I got around this using a tool already within Eagle.

The final issue is that the Sparkfun ULP was made for their scenario and there are lots of things which are irrelevant and the default settings need changing each time. I also didn’t want to adopt their workflow concerning design rules and CAM processor config. So I streamlined the script for me (I could do more; there is some cruft remaining). Here it is: Panelizer2

The Procedure

1. Prepare a New Layer with Component Names

From the board in Eagle: Tools > Panelize.

This does not actually panelize anything, but generates a script by iterating through all the components. The result of executing the script is that the component names are written into layers 125 (aka “_tNames” for top components) and 126 (aka “_bNames”) for bottom components). Since these are just written as text, they no longer need to follow the unique naming rule; they are not names!

At this point, show only the new layers and delete anything you dont want (I have found some component names which I deleted from the board re-appear in the new layers). Also: be aware that items in the new layers are created every time the Panelize tool is run.

2. Run the Panelizer ULP

If the Sparkfun ULP works for you, go ahead. There is a tutorial on Or maybe you have spaces in your file paths and can use it with the fix noted above. Alternatively, if you are using Seeed Studio, try using my hacked version.

Run a DRC now!

3. Run a Modified CAM Process

The upshot of step 1 is that we have component names in four layers (two for the top and two for the bottom) and the ones which your usual CAM process rules will put into the silk-screen layer are the wrong ones. The change required is quite simple. Start by taking a copy of the “.cam” file and open it in a plain text editor (Notepad will do, but I prefer “Notepad++”).

You are looking for the occurrence of 25 or 26 within a “layers” structure. For example, a typical setup for a top silk-screen would include the placement and names and define this using:

“layers”: [

Simply change the 25 to 125 (i.e. _tNames) and 26 to 126.

Then just run your modified CAM file in the CAM Processor.

Notes Concerning Seeed Studio

I’ve found them fast (accounting for shipping from China), cheap, and (so far) of good quality. I use the basic PCB service, which has a 100mm x 100mm standard board and panelisation of identical boards attracts no additional fee. There are some rules concerning panelisation which the revised ULP adopts.

Blind Alley

In addition to the gremlins with the Sparkfun ULP, I did attempt to use “gerbmerge”; I had used this quite a few years ago. This time I used gerbmerge3, which is an adapted version for Python 3 (the older version was Python2 which has not been maintained for several years). Unfortunately, after setting up the config files, while the program ran, it barfed on one of my gerber files due to a directive which it did not recognise: “%MOMM*%”. I failed to find out what the significance of this is and whether I could safely hack the code to ignore it… only to find there was some other similar issue… and a rat hole of misery.