Fix Random function

examples/LoRandom/LoRandom.ino

@@ -0,0 +1,92 @@
+/*
+  LoRandomSeed
+
+  Example demonstrating how to generate random numbers using LoRa.
+
+  created 7 Sep 2020
+  by Kongduino
+  adapted by Andres Sabas
+  
+  SX1276 Register (address)     Register bit field (bit #)      Values    Note
+  RegOpMode (0x01)              LongRangeMode[7]                ‘1’       LoRa mode enable
+                                Mode[2:0]                       ‘101’     Receive Continuous mode
+  ------------------------------------------------------------------------------------------------------------------
+  RegModemConfig1 (0x1D)        Bw[7:4]                         ‘0111’    ‘0111’ for 125kHz modulation Bandwidth
+                                CodingRate[3:1]                 ‘001’     4/5 error coding rate
+                                ImplicitHeaderModeOn[0]         ‘0’       Packets have up-front header
+  ------------------------------------------------------------------------------------------------------------------
+  RegModemConfig2 (0x1E)        SpreadingFactor[7:4]            ‘0111’    ‘0111’ (SF7) = 6kbit/s
+
+  To generate an N bit random number, perform N read operation of the register RegRssiWideband (address 0x2c)
+  and use the LSB of the fetched value. The value from RegRssiWideband is derived from a wideband (4MHz) signal strength
+  at the receiver input and the LSB of this value constantly and randomly changes.
+*/
+
+#include <SPI.h>
+#include <LoRa.h>
+
+void hexDump(unsigned char *buf, uint16_t len) {
+  String s = "|", t = "| |";
+  Serial.println(F("  |.0 .1 .2 .3 .4 .5 .6 .7 .8 .9 .a .b .c .d .e .f |"));
+  Serial.println(F("  +------------------------------------------------+ +----------------+"));
+  for (uint16_t i = 0; i < len; i += 16) {
+    for (uint8_t j = 0; j < 16; j++) {
+      if (i + j >= len) {
+        s = s + "   "; t = t + " ";
+      } else {
+        char c = buf[i + j];
+        if (c < 16) s = s + "0";
+        s = s + String(c, HEX) + " ";
+        if (c < 32 || c > 127) t = t + ".";
+        else t = t + (char)c;
+      }
+    }
+    uint8_t index = i / 16;
+    Serial.print(index, HEX); Serial.write('.');
+    Serial.println(s + t + "|");
+    s = "|"; t = "| |";
+  }
+  Serial.println(F("  +------------------------------------------------+ +----------------+"));
+}
+
+void setup() {
+  Serial.begin(115200);
+  while(!Serial);
+  Serial.print(F("\n\n\n[SX1276] Initializing ... "));
+  LoRa.setPins(SS, RFM_RST, RFM_DIO0);
+  Serial.println("SS: " + String(SS));
+  Serial.println("RFM_RST: " + String(RFM_RST));
+  Serial.println("RFM_DIO0: " + String(RFM_DIO0));
+  Serial.println("RFM_SWITCH: " + String(RFM_SWITCH));
+  if (!LoRa.begin(868E6)) {
+    Serial.println("Starting LoRa failed!");
+    while (1);
+  }
+  Serial.print("Setting up LoRa ");
+
+  #ifdef SAMR34
+  pinMode(RFM_SWITCH, OUTPUT);
+  digitalWrite(RFM_SWITCH, 1);
+  #endif
+
+  LoRa.setTxPower(20, PA_OUTPUT_PA_BOOST_PIN);
+  LoRa.setPreambleLength(8);
+  LoRa.LoRandomSeed();
+  Serial.println("[o]");
+  delay(1000);
+  Serial.println("End of setup\n\n");
+}
+
+void loop() {
+  unsigned char randomStock[256];
+  // We'll build a stock of random bytes for use in code
+  uint8_t randomIndex = 0;
+  uint16_t i;
+  for (i = 0; i < 256; i++) {
+    uint8_t x = LoRa.random();
+    randomStock[i] = x;
+  }
+  randomIndex = 0;
+  hexDump(randomStock, 256);
+  delay(2000);
+}

src/LoRa.cpp

@@ -607,9 +607,21 @@ void LoRaClass::setOCP(uint8_t mA)
   writeRegister(REG_OCP, 0x20 | (0x1F & ocpTrim));
 }
 
+void LoRaClass::LoRandomSeed() {
+  writeRegister(REG_OP_MODE, 0x72);
+  writeRegister(REG_MODEM_CONFIG_1, 0x72);
+  writeRegister(REG_MODEM_CONFIG_2, 0x70);
+}
+
 byte LoRaClass::random()
 {
-  return readRegister(REG_RSSI_WIDEBAND);
+  uint8_t x = 0;
+  for (uint8_t j = 0; j < 8; j++) {
+    x += (readRegister(REG_RSSI_WIDEBAND) & 0x01);
+    x = x << 1;
+    delay(1);
+  }
+  return x;
 }
 
 void LoRaClass::setPins(int ss, int reset, int dio0)

src/LoRa.h

@@ -81,7 +81,8 @@ class LoRaClass : public Stream {
   // deprecated
   void crc() { enableCrc(); }
   void noCrc() { disableCrc(); }
-
+
+  void LoRandomSeed();
   byte random();
 
   void setPins(int ss = LORA_DEFAULT_SS_PIN, int reset = LORA_DEFAULT_RESET_PIN, int dio0 = LORA_DEFAULT_DIO0_PIN);