Home Assistant P1 Logger

Home Assistant custom component for taking in (custom) Smart Meter P1 port communications.

If your installation is within cable reach of your smart meter, I recommend you use the official DSMR Slimme Meter integration.

I made this specifically because my meter is in the basement. I had to use a very low bandwidth serial link, so I'm sending over a limited subset of the parsed data.

Hardware

The hardware I use for this project is a DIY circuit board based on the HC-12 SI4463 wireless UART modules.

I used some microcontrollers I had lying around (ATMega128A) to parse the P1 telegrams into a compact binary format with CRC and send it over the highest gain/lowest bandwidth connection possible. This together with the use of a directional antenna was needed to receive the signal reliably trough 3 floors of concrete with in-floor heating.

On the receiving end, a simple USB-TTY cable is used, directly attached to a HC-12.

The HC-12 mode is set to FU4 mode, with baud rate of 1200bps. This limits data to "60 bytes or less", at intervals of "no less than 2 seconds". This mode setting is done manually via AT commands, since it only needs to be done once.

If you would like schematics or code of this hardware, let me know. I even have some circuit boards left, I will ship them at cost if you would like to build your own.

Related repo: https://github.com/dries007/P1logger

Software

This is an addon for Home Assistant in the form of a custom component that can be installed via HACS.

The code is based on the official DSMR integration.

A single packet follows this struct, with Little Endian encoding and struct packing enabled:

Type	Name	Source	Value
uint8[3]	pre	Magic numbers	0x42, 0x42, 0xFF
unit32	timestamp	0-0:1.0.0	Timestamp in seconds since 2000-01-01 00:00:00
unit32	meter_delivered_t1	1-0:1.8.1	Delivered meter reading for tariff 1 in Wh.
unit32	meter_delivered_t2	1-0:1.8.2	Delivered meter reading for tariff 2 in Wh.
unit32	meter_injected_t1	1-0:2.8.1	Injected meter reading for tariff 1 in Wh.
unit32	meter_injected_t2	1-0:2.8.2	Injected meter reading for tariff 2 in Wh.
uint16	sum_power_delivered	1-0:1.7.0	Sum "actual" power for all phases in W.
uint16	sum_power_injected	1-0:2.7.0	Sum "actual" power for all phases in W.
uint16[3]	power_per_phase_delivered	1-0:21.7.0, 1-0:41.7.0, 1-0:61.7.0	Instantaneous "actual" power for every phase in W.
uint16[3]	power_per_phase_injected	1-0:22.7.0, 1-0:42.7.0, 1-0:62.7.0	Instantaneous "actual" power for every phase in W.
uint16[3]	voltage_per_phase	1-0:32.7.0, 1-0:52.7.0, 1-0:72.7.0	Instantaneous voltage for every phase in .1V.
uint16[3]	current_per_phase	1-0:31.7.0, 1-0:51.7.0, 1-0:71.7.0	Instantaneous "actual" power for every phase in .01A.
unit32	gas_volume	0-1:24.2.3	Gas volume in 0.001m3.
uint8	tariff	0-0:96.14.0	Tariff currently in effect. (1/2 for normal/night in BE)
uint16	checksum	CRC16	Calculated over all of the previous bytes.
uint8[2]	post	Magic numbers	0x55, 0xAA

String for Python's struct module: <BBBIIIIIHHHHHHHHHHHHHHIBHBB.

If a value is -1, it indicates the value was not present in the telegram. All normal numbers are positive, as delivered and injected are counted separately.

To communicate errors, the MSB of timestamp is set. Treat payload after timestamp as raw bytes to be discarded. Timestamp codes:

• 0xFFFF_FFFF Blank telegram send. Usually a bad sign.
• 0x8000_0000 No telegram received within expected timeframe. Optional.
• 0x8000_0002 CRC mismatch.

This addon exposes each of the previously mentioned fields as a sensor to Home Assistant except for pre, post, and checksum.