[BK7231N / CB3S] Atorch AT2P - "HD Color Screen" DIN-rail relay/energy meter with RS485
Teardown of this energy meter from AliExpress https://www.aliexpress.com/item/1005004917583615.html
The overall build quality is excellent. The screen is bright and clear, and the device offers a full set of features. However, there are a couple of drawbacks:
•The RS485 interface does not use Modbus; instead, it relies on a proprietary protocol developed by Atorch.
•The device is not bi-directional, meaning it cannot measure exported power. This I believe to be a software limitation.
Opening the device is simple, remove the locking mechanism and 2 Philips screws.
Once opened, the construction appears high quality. The daughterboard is connected via a 10-pin standard interface, the power electronics are well-arranged, and there's a small beeper for audible alerts.
The meter contains a CB3S TuyaMCU, which is responsible for WiFi connectivity and integration with the Tuya Cloud/App. This connects via UART to a secondary CH573F MCU, which handles power monitoring, screen, buttons and RS485 communication. Pins 1 and 2 are TX and RX for RS485.
The RS485 module works directly with ESPHome if you connect Pins 1 and 2 to RX/TX respectively (I have tested this) and it works fine as long as a 120 Ohm resistor is placed across A and B.
If Pins 1 and 2 were disconnected from the CH573F and instead connected to the CB3S TuyaMCU, Modbus control via ESPHome could theoretically be enabled.
This IC seems to be there for 3.3V DC power regulator:
One key IC is the AC power metering chip, but unfortunately, all its markings have been removed. I have attempted to mark it as best as possible. If anyone can identify it, please let me know!
I still have the device and it is currently unused. If anyone has questions or wants me to de-solder the TuyaMCU to read the flash, or perform any other modifications, let me know!
The overall build quality is excellent. The screen is bright and clear, and the device offers a full set of features. However, there are a couple of drawbacks:
•The RS485 interface does not use Modbus; instead, it relies on a proprietary protocol developed by Atorch.
•The device is not bi-directional, meaning it cannot measure exported power. This I believe to be a software limitation.
Opening the device is simple, remove the locking mechanism and 2 Philips screws.
Once opened, the construction appears high quality. The daughterboard is connected via a 10-pin standard interface, the power electronics are well-arranged, and there's a small beeper for audible alerts.
The meter contains a CB3S TuyaMCU, which is responsible for WiFi connectivity and integration with the Tuya Cloud/App. This connects via UART to a secondary CH573F MCU, which handles power monitoring, screen, buttons and RS485 communication. Pins 1 and 2 are TX and RX for RS485.
The RS485 module works directly with ESPHome if you connect Pins 1 and 2 to RX/TX respectively (I have tested this) and it works fine as long as a 120 Ohm resistor is placed across A and B.
If Pins 1 and 2 were disconnected from the CH573F and instead connected to the CB3S TuyaMCU, Modbus control via ESPHome could theoretically be enabled.
This IC seems to be there for 3.3V DC power regulator:
One key IC is the AC power metering chip, but unfortunately, all its markings have been removed. I have attempted to mark it as best as possible. If anyone can identify it, please let me know!
I still have the device and it is currently unused. If anyone has questions or wants me to de-solder the TuyaMCU to read the flash, or perform any other modifications, let me know!
Comments
Thank you for this interesting presentation! Would you be able to dump the 2MB Flash of the BK7231 module? https://github.com/openshwprojects/BK7231GUIFlashTool This would be very useful for us, as... [Read more]
I always advocate for a firmware dump and share! Added after 2 [minutes]: Same? https://www.elektroda.com/rtvforum/topic3946239.html Added after 8 [minutes]: odd, that other device doesn't... [Read more]
I think I may need to go through all the topics and check if each has entry on list... because we sometimes forget about it. [Read more]
yes. I have caught quite a few by going back through, but there's undoubtedly more, I wasn't terribly methodical. [Read more]
I can get a list of all topics in IoT section and then write a little script to compare it with what we have on Teardowns List, would that help? [Read more]
Hmm. Maybeee. [Read more]
Not so cool at all. It has a residual current protection option, using an external transformer. The trouble is that although this function is disabled, or even if there is no transformer, this protection... [Read more]
Maybe a faulty copy? Isn't there an option to turn it off? [Read more]
. There isn't. You can only raise the threshold, but the maximum is probably 300mA, but that's not enough. [Read more]
@pkaczmarek2 As requested, I have de-soldered the MCU and performed a firmware backup. I presume this is what you were looking for. Also, Atorch is sometimes branded as HiDANCE, which I believe... [Read more]
It is a very similar device! I believe Atorch is sometimes branded as HiDANCE, which seems to be the same company. However, that particular unit doesn’t include RS485, and some of the PCB layouts are different. ... [Read more]
hefty list of dpIDs for this device DP Listx 1 → Switch state 9 → Countdown 17 → Add Electricity 18 → Current 19 → Power 20 → Voltage 101 → Price 102 → Bill 103 → Add Bill 104... [Read more]
. It was loaded, I also don't rule out that it might have scored some sort of short circuit. Do you know how to turn it off? [Read more]
Hello, good morning. I'm having problems with something very similar. It makes it impossible to use the device, as it only displays "Lakage Protection" and doesn't allow me to do anything else, I've even... [Read more]
No. I removed it and put the old meter back in. [Read more]