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SPPro/README.md
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2026-06-16 05:02:54 +10:00

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# SPPro Access
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.
Serial decoding is ported to portable C from the open-source [neerolyte/selpi](https://github.com/neerolyte/selpi) project.
* 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 is a **portable C parser** for the SP PRO serial protocol (ported from
[neerolyte/selpi](https://github.com/neerolyte/selpi)), packaged as a **PlatformIO /
Arduino library** with an optional thin C++ wrapper. Full protocol notes are in
[docs/PROTOCOL.md](docs/PROTOCOL.md) and the ESP32 wiring in
[docs/HARDWARE.md](docs/HARDWARE.md).
## Layout
```
src/ sppro.h / sppro.c portable C core: CRC, frame build/parse,
md5.h / md5.c register map + scaling, MD5 login, session layer
Sppro.h optional header-only C++/Arduino wrapper (any Stream)
examples/ Esp32SerialMonitor/ ESP32 example (.ino + platformio.ini)
docs/ PROTOCOL.md wire protocol, CRC, login, register map + scaling
HARDWARE.md RS-232 pinout and MAX3232 -> ESP32 wiring
extras/ host/main.c Linux serial-console dashboard (termios)
tests/test_sppro.c host known-answer tests (no hardware)
Makefile host build (test / console)
library.json, library.properties, keywords.txt PlatformIO + Arduino manifests
```
The core (`src/sppro.*`) 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, an MCU,
or anything with a serial port. Only `src/` and `examples/` are part of the published
library; `extras/` is development tooling (Arduino ignores it).
## Use on Arduino / ESP32 (PlatformIO or Arduino IDE)
Add the library (`lib_deps = SPPro` in PlatformIO once published, or *Sketch → Include
Library* in the Arduino IDE), then use the `Sppro` wrapper, which works over **any**
Arduino `Stream` (HardwareSerial, SoftwareSerial, WiFiClient, …):
```cpp
#include <Sppro.h>
Sppro sp(Serial2); // wraps any Stream
void setup() {
Serial2.begin(57600, SERIAL_8N1, 16, 17); // via a MAX3232 level shifter
sp.login(""); // "" = no serial password
sp.readScales();
}
void loop() {
Serial.println(sp.value("BatteryVolts")); // scaled value, or NAN on error
delay(5000);
}
```
A complete ESP32 example is in
[`examples/Esp32SerialMonitor/`](examples/Esp32SerialMonitor); build it standalone with
`cd examples/Esp32SerialMonitor && pio run` (it links the parent library via
`lib_deps = symlink://../..`). See [docs/HARDWARE.md](docs/HARDWARE.md) — the SP PRO port
is RS-232 (±12 V) and **needs a MAX3232 level shifter**; never wire it straight to a GPIO.
## Build & test on a host (no hardware)
```sh
cd extras
make test # build and run the host unit tests
make host # build ./build/sppro-console
```
Then, with a real SP PRO + USB-RS232 adapter:
```sh
./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`.
## Use the pure C core (non-Arduino: ESP-IDF, STM32, Linux, Zephyr …)
```c
#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);
```
`extras/host/main.c` is a full worked example of the two callbacks (termios). 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 (`cd extras && make test`): CRC against selpi's documented
`0xa000` frame, MD5 known-answers, frame round-trips, and the scaling formulas. The
ESP32 example + C++ wrapper are verified to compile/link via PlatformIO. **Not yet
verified against physical hardware** — confirm decoded values against the inverter's own
display.
- On 8-bit AVR, `double` is 32-bit float, so very large `Wh` accumulators lose some
precision (fine for display). Use the 32-bit-int register types directly if you need
exact counts.
- 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.
## See Also
* selpi - a Python set for seletronics
* https://github.com/neerolyte/selpi
* splink-influx
* https://github.com/angus-g/splink-influx