intial test version

2026-06-04 21:35:07 +10:00
commit 4ea1e12ee9
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+/**
+ * BluettiCRC - CRC-16/MODBUS helpers for the Bluetti BLE protocol
+ *
+ * Ported from the Bluetti_ESP32_Bridge project (crc16.h / utils.cpp).
+ * Polynomial 0xA001 (reversed 0x8005), initial value 0xFFFF.
+ *
+ * Copyright (c) 2026 Scott Penrose
+ * License: MIT
+ */
+
+#ifndef BLUETTI_CRC_H
+#define BLUETTI_CRC_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+// Update a running CRC-16/MODBUS with one byte.
+static inline uint16_t bluettiCrc16Update(uint16_t crc, uint8_t a) {
+    crc ^= a;
+    for (int i = 0; i < 8; ++i) {
+        if (crc & 1)
+            crc = (crc >> 1) ^ 0xA001;
+        else
+            crc = (crc >> 1);
+    }
+    return crc;
+}
+
+// CRC-16/MODBUS over a buffer (init 0xFFFF).
+static inline uint16_t bluettiModbusCrc(const uint8_t* buf, size_t len) {
+    uint16_t crc = 0xFFFF;
+    for (size_t i = 0; i < len; i++) {
+        crc = bluettiCrc16Update(crc, buf[i]);
+    }
+    return crc;
+}
+
+// Swap the two bytes of a 16-bit value (used to place write values big-endian).
+static inline uint16_t bluettiSwapBytes(uint16_t v) {
+    return (uint16_t)((v << 8) | (v >> 8));
+}
+
+#endif // BLUETTI_CRC_H