Initial commit: Simple Sensor firmware for Heltec T114 with BME280

- MeshCore-based Simple Sensor firmware
- Heltec T114 without display
- BME280 sensor support (temp/humidity/pressure)
- Radio: 868.856018 MHz, SF7, BW62.5 kHz, CR4/7
- 2-byte path hash
- PlatformIO project

lib/ed25519/sha512.h

@@ -0,0 +1,21 @@
+#ifndef SHA512_H
+#define SHA512_H
+
+#include <stddef.h>
+
+#include "fixedint.h"
+
+/* state */
+typedef struct sha512_context_ {
+    uint64_t  length, state[8];
+    size_t curlen;
+    unsigned char buf[128];
+} sha512_context;
+
+
+int sha512_init(sha512_context * md);
+int sha512_final(sha512_context * md, unsigned char *out);
+int sha512_update(sha512_context * md, const unsigned char *in, size_t inlen);
+int sha512(const unsigned char *message, size_t message_len, unsigned char *out);
+
+#endif