After reviewing different Helium miner like RAK, Sensecap, Kerlink, Nebra… now comes the Cotx-X3 miner. This miner has a long story and a bad reputation, due to something not really clean the maker did with the first units.

This is not related to the hardware quality and I’ve been happy to buy some of them for reviewing it. This miner is a full miner, based on a standard design using a Raspberry Pi 4. It has the particularity of having a front screen and an audio jack ! Don’t laughs, the reason is simple, this device has a different usage before becoming an helium miner.

Getting it out of the box and connect.

Inside the COTX package you have all what you need to start with it : miner, antenna, power cable but also network cable and adaptor for the antenna connector. It’s rare and good to be noticed.

You just need to connect the antenna (make sure you select the right connector, the second one is unconnected and won’t work) and connect the USB power in front.

In the version I received, it was not possible to register directly the miner from the Helium application. The miner needs to get a first update from the network. For this reason you need to connect it to the network over Ethernet for the first time and about 10-20 minutes. Once you have done this, the miner is ready to be associated as any other miner using the Helium application. You can use Wifi, even if I do not recommend it: RPI4 Wifi antenna is not good, metallic casing is not good for WiFi waves and WiFi is not stable enough for application like miners in general.

When associating with the application you need activate Bluetooth, here you need to press the button on the front and wait until the on screen timer reached 0. This is different from other miners where usually a single click is enough. The front icon helps you to see the status.

After being installed you will be able to access the web dashboard from the local IP displayed on the front panel. This front panel is really good for getting it and save some time in configuring the port forwarding or access the dashboard.

Since two weeks that hotspot has been installed on its final site, it has a really normal rewarding, the same as the other on the same kind of location. I did not have any issue like abnormal resync or anything bad.

Inside the miner

Outside, you can easily access the SD CARD. This one is a Kingston Canvas Select Plus 32GB. It is not looking like an Endurance SDCARD and the size is in my point of view too small for the current miners. There is an important risk of failure in the 6 month due to the technology of the SDCARD and a risk of recurrent sync activity due to the size. This second point is compensated by an efficient Fast Sync solution based on validator snapshots as most of the hardware providers are currently doing. This is the weakness of that hotspot.

Once open, you can see two boards, as usual: the radio board on the top and the RPI board on the bottom. A third board is on the front panel. You can also see that the second RF connector is just not connected (on the back panel on the photo). It exists because this device has been initially made for a different purpose and it had a second antenna for this.

The miner has a metal casing, this one is really good to dissipate the PI4 heat. It becomes reasonably warm after a couple of hours running. Compared to the RAK design where the heat transfert between the MCU and the casing is really well designed, here we just have a heatsink on top of the MCU without any conducting stuff to the casing. By the way, it seems to work well, I will see the long term efficiency of this.

The RPI4 as been customized to enter in the really compact casing with the radio board. As you can see some of the connectors are not soldered like the second USB, the camera connector and the second HDMI. I don’t know if it is a special edition for them or if they are unsoldering the pieces on every PI they are mounting. In term of engineering, I like what they have been done and the result in term of integration in the tiny enclosure with the front panel.

The front panel board contains the SD-CARD, the different user interaction components like the panel an buttons. The power supply comes from the PI Hat that has the LoRaWan concentrator module:

You can see on the board the power connector and the audio jack. On the top of the board you see the LoRaWan module (no brand) and the secure element. The board is simple. You also have the green big connector. I think it has no big interest and is mainly here to not have a hole on back of the miner casing.

Certain of the COTX the community received have bad quality soldering like you can see above. This was not a problem to use the COTX-X3 miner but it shows that the quality of the assembly can vary from one piece to another.

Dashboard

The COTX-X3 device have different ways to monitor it’s activity. You can access a Web dashboard on www.cotx-sg.io and add you hotspot on it.

This one looks like the sensecap one at first but is really different. This tools allows to monitor multiple miners. Such feature is really useful to manage miners you can’t access locally. This is important when your hotspots are hosted or used behind a 4G connection. On this point COTX currently proposes a really limited solution. It basically displayed what you can get from Helium API. And we all knows that we can’t trust Helium API information about miner health. As an exemple here the miner height reported is 0. You are currently not able to perform any remote action like turbo sync or reboot. I hope that will be evolve in the next month. thanks to this COTX-X3 could be part of the best miner I’ve tested.

Where the COTX is different to most of the solution I have tested is on the local dashboard. The one you can access from the LAN. This one contains advanced graphic with your earning and the most import point the block height with the progress.

This dashboard is really good with all what you need to manage your hotspot. You also have button to restart… and to load a snapshot from validator. So you can quickly sync your hotspot that way.

Radio performance

Cotx-M3 has a really low radio performance, the miner is really subject to radio noise around. On the two of them I’ve deployed, one of them has a correct performance but the second one has been deployed close to a Power Line Communication adapter. The consequence is that the miner never received a witness. As a consequence it is recommended to use a radio filter when deploying a Cotx-M3 miner.