Build a system that can connect to an SPPro Serial Port to get sensible data out of it to display it on a serial console and be used in other projects.

PyAware seems to already decode Serial Data. Look at porting that to portable C for decoding.

Hardware necessary to connect to SPPro
- https://www.selectronic.com.au/documents/TechNotes/TN0050_02%20SP%20PRO%20Serial%20Port%20Pin-out.pdf
- How to connect this to an ESP32
Parse Serial Data
- A simple C parser, portable to allow parsing

This repo now contains a portable C parser for the SP PRO serial protocol, ported from neerolyte/selpi (PyAware itself is not open source). Full protocol notes are in docs/PROTOCOL.md and the ESP32 wiring in docs/HARDWARE.md.

Layout

src/      sppro.h / sppro.c   portable core: CRC, frame build/parse,
          md5.h  / md5.c       register map + scaling, MD5 login, session layer
host/     main.c              Linux serial-console dashboard (termios)
esp32/    sppro_esp32.ino     ESP32 (Arduino) example, reuses the core unchanged
tests/    test_sppro.c        host known-answer tests (no hardware)
docs/     PROTOCOL.md         wire protocol, CRC, login, register map + scaling
          HARDWARE.md         RS-232 pinout and MAX3232 -> ESP32 wiring

The core (src/) is C99, no dynamic allocation and no I/O — it builds/parses byte buffers and converts raw words to units. I/O is supplied by the caller through a small sppro_transport_t read/write callback, so the same code runs on a host or an MCU.

Build & test

make test     # build and run the host unit tests (no hardware needed)
make host     # build ./build/sppro-console

Run against a real SP PRO

Wire it up per docs/HARDWARE.md (RS-232, needs a MAX3232 level shifter, 57600 8N1), then:

./build/sppro-console /dev/ttyUSB0 [serial_password] [interval_seconds]

It logs in, reads the device scale factors, and prints a refreshing dashboard of battery voltage, state of charge, load/solar/generator power, and energy totals. The serial-port password is set on the inverter (front panel → Settings → Communications); pass "" if none is configured, or set SPPRO_PASSWORD.

Using the core in another project

#include "sppro.h"

sppro_transport_t t = { my_read, my_write, my_ctx };   /* your serial callbacks */
sppro_session_login(&t, "");                            /* MD5 challenge/response */

sppro_scales_t scales;
sppro_session_read_scales(&t, &scales);

double soc, vbat;
sppro_session_read(&t, sppro_reg_by_name("BattSocPercent"), &scales, &soc);
sppro_session_read(&t, sppro_reg_by_name("BatteryVolts"),   &scales, &vbat);

For environments with their own protocol loop, the pure helpers (sppro_build_query, sppro_parse_query_response, sppro_decode, sppro_crc16, sppro_login_response) can be used without the session/transport layer.

Status & caveats

Verified by host unit tests: CRC against selpi's documented 0xa000 frame, MD5 known-answers, frame round-trips, and the scaling formulas. Not yet verified against physical hardware — confirm decoded values against the inverter's own display.
Read-only monitoring is the focus. Write framing (sppro_build_write / sppro_session_write) exists because login needs it, but no inverter-setting writes are wired into the demos.
The register table is a useful subset; add rows from selpi memory/variable.py as needed (decoding is table-driven).

Not-yet-mapped registers (future work)

SPPRO_REGISTERS covers all the live measurements plus the most useful energy totals. The following entries exist in selpi memory/variable.py but are not in the table yet. All are decodable by the existing converters — adding them is pure data (new rows), no new code.

Scale factor (already used internally via sppro_scales_t, just not exposed as a row):

Name	Addr	Type	Conv
CommonScaleForInternalVoltages	41005	u16	raw

Battery "out" energy accumulators (all u32, dc_wh):

Name	Addr
BattOutkWhAcc	41143
QuickView_BattOutkWhAcc	41178
BattOutkWhPreviousAcc	41356
BattOutkWh7DayAcc / …AccAvg	41358 / 41360
BattOutkWh30DayAcc / …AccAvg	41362 / 41364
BattOutkWh365DayAcc / …AccAvg	41366 / 41368
BattOutkWhYearAcc / …AccAvg	41370 / 41372
BattOutkWhResetableAcc / …AccAvg	41374 / 41376

Other DC energy:

Name	Addr	Type	Conv
DCkWhOut	41257	u32	dc_wh
Shunt1WhTotalAcc	41305	s32	dc_wh
Shunt1WhTodayAcc	41146	s16	dc_wh

AC energy (input / export / load / solar):

Name	Addr	Type	Conv
ACInputWhTotalAcc	41459	u32	ac_wh
ACInputWhTodayAcc	41151	u16	ac_wh
ACExportWhTotalAcc	41499	u32	ac_wh
ACExportWhTodayAcc	41154	u16	ac_wh
ACLoadWhAcc	41150	u16	ac_wh
ACSolarWhTotalAcc	41519	u32	ac_wh
ACSolarWhTodayAcc	41157	s16	ac_wh

Two quirks when transcribing these:

ACSolarWhTotalAcc (41519) is the same address as the already-included TotalKacokWhTotalAcc (41519) — selpi just has two names for it.
ACGeneratorPower appears twice in selpi's MAP; the second definition wins (s16, ac_w_signed) — that is the one already in the table. The first (u32, ac_w) is dead.

README.md

SPPro Access