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-rw-r--r--tracker-stm32/src/main.ino79
1 files changed, 72 insertions, 7 deletions
diff --git a/tracker-stm32/src/main.ino b/tracker-stm32/src/main.ino
index da82e01..ed1d570 100644
--- a/tracker-stm32/src/main.ino
+++ b/tracker-stm32/src/main.ino
@@ -4,9 +4,15 @@
#include <SparkFun_u-blox_GNSS_Arduino_Library.h>
#include <SD.h>
-File myFile;
+constexpr char *CALLSIGN = "HB9EGM";
+constexpr int SSID = 12;
+constexpr char SYMBOL_TABLE_IDENTIFIER = '/';
+constexpr char SYMBOL_CODE_BICYCLE = 'b';
+#if 0
+File myFile;
constexpr int SD_CS = 17;
+#endif
// SX1278 has the following connections:
// NSS pin: PD14 (Arduino 10)
@@ -18,8 +24,39 @@ SFE_UBLOX_GNSS gnss;
long lastGnssPoll = 0;
long lastPositionReport = 0;
-constexpr size_t POSITION_REPORT_LEN = 32;
-char positionReport[POSITION_REPORT_LEN+1];
+
+constexpr size_t MAX_REPORT_LEN = 32;
+size_t report_len = 0;
+uint8_t report[MAX_REPORT_LEN];
+
+const char* digits = " 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-./?@";
+
+#define callsign_int_t uint32_t
+callsign_int_t encodeCallsign(const char *callsign) {
+ // Encode CCCC according to aprs434.github.io/code/codec.cpp
+ const int b = 37;
+
+ callsign_int_t result;
+ callsign_int_t weight;
+ int i, j, k, ch;
+
+ result = 0, weight = 1;
+ for (i = j = strlen(callsign); i > 0; i--) { // iterate over input string
+ ch = toupper(callsign[i-1]);
+ for (k = 0; k < strlen(digits); k++) { // lookup char index
+ if (digits[k] == ch) {
+ break;
+ }
+ }
+ if (k == strlen(digits)) // ignore if ch not found in digits
+ continue;
+ result = result + ((k) * weight);
+ weight = weight * b;
+ }
+
+ return result; // result can be pow(42,51)!
+}
+
static char letterize(int x) {
return (char) x + 65;
@@ -54,13 +91,14 @@ void setup() {
Serial.begin(9600);
pinMode(LED_BUILTIN, OUTPUT);
+#if 0
pinMode(SD_CS, OUTPUT);
if (!SD.begin(SD_CS)) {
Serial.println("SD init failed!");
return;
}
-
+#endif
Wire.begin();
@@ -175,12 +213,39 @@ void loop()
digitalWrite(LED_BUILTIN, HIGH);
- ssize_t len = snprintf(positionReport, POSITION_REPORT_LEN, "HB9EGM %s", locator);
+ // Encode LoRa message according to aprs434.github.io
+ const uint32_t callsign_EEEE = encodeCallsign(CALLSIGN);
+
+ report_len = 0;
+ // Callsign encoded as CCCC
+ report[report_len++] = (callsign_EEEE >> 24) & 0xFF;
+ report[report_len++] = (callsign_EEEE >> 16) & 0xFF;
+ report[report_len++] = (callsign_EEEE >> 8) & 0xFF;
+ report[report_len++] = callsign_EEEE & 0xFF;
+
+ // D SSID Path Code and Data Type Code
+
+ const int date_type_code = 0; // compressed geolocation
+ const int path_code = 2; // metropolitan mobile
+ report[report_len++] = SSID * 16 + path_code * 4 + date_type_code;
+
+ // / Symbol Table Identifier
+ report[report_len++] = SYMBOL_TABLE_IDENTIFIER;
+#warn "TODO longitude and latitude"
+ // XXXX Base91 Longitude
+ // YYYY Base91 Latitude
+ // $ Symbol Code
+ report[report_len++] = SYMBOL_CODE_BICYCLE;
+ // cs Course and Speed
Serial.print(F("TX: "));
- Serial.print(positionReport);
+ // This is the old custom report I used before adopting aprs434.github.io,
+ // it is just callsign SPACE locator sent as ASCII
+ Serial.print(CALLSIGN);
+ Serial.print(" ");
+ Serial.println(locator);
- int state = radio.transmit(positionReport, len);
+ int state = radio.transmit(report, report_len);
if (state == RADIOLIB_ERR_NONE) {
Serial.print(F(" RFM OK Datarate: "));