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‎LICENSE‎

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MIT License
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Copyright (c) 2020 Kongduino
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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‎LoRandom.h‎

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/*
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SX1276 Register (address) Register bit field (bit #) Values Note
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RegOpMode (0x01) LongRangeMode[7] ‘1’ LoRa mode enable
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Mode[2:0] ‘101’ Receive Continuous mode
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------------------------------------------------------------------------------------------------------------------
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RegModemConfig1 (0x1D) Bw[7:4] ‘0111’ ‘0111’ for 125kHz modulation Bandwidth
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CodingRate[3:1] ‘001’ 4/5 error coding rate
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ImplicitHeaderModeOn[0] ‘0’ Packets have up-front header
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------------------------------------------------------------------------------------------------------------------
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RegModemConfig2 (0x1E) SpreadingFactor[7:4] ‘0111’ ‘0111’ (SF7) = 6kbit/s
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To generate an N bit random number, perform N read operation of the register RegRssiWideband (address 0x2c)
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and use the LSB of the fetched value. The value from RegRssiWideband is derived from a wideband (4MHz) signal strength
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at the receiver input and the LSB of this value constantly and randomly changes.
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*/
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#define RegOpMode 0x01
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#define RegModemConfig1 0x1D
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#define RegModemConfig2 0x1E
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#define RegRssiWideband 0x2C
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void writeRegister(uint8_t reg, uint8_t value);
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uint8_t readRegister(uint8_t reg);
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// Provide your own functions, which will depend on your library
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uint8_t modemconf1;
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uint8_t modemconf2;
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void setupLoRandom() {
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modemconf1 = readRegister(RegModemConfig1);
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modemconf2 = readRegister(RegModemConfig2);
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writeRegister(RegOpMode, 0b10001101); // MODE_LONG_RANGE_MODE 0b1xxxxxxx || LowFrequencyModeOn 0bxxxx1xxx || MODE_RX_CONTINUOUS 0bxxxxx101
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writeRegister(RegModemConfig1, 0b01110010);
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writeRegister(RegModemConfig2, 0b01110000);
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}
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void resetLoRa() {
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writeRegister(RegOpMode, 0b10000001); // MODE_LONG_RANGE_MODE 0b1xxxxxxx || MODE_STDBY 0bxxxxxxx1
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writeRegister(RegModemConfig1, modemconf1);
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writeRegister(RegModemConfig2, modemconf2);
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}
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uint8_t getLoRandomByte() {
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uint8_t x = 0;
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for (uint8_t j = 0; j < 8; j++) {
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x += (readRegister(RegRssiWideband) & 0b00000001);
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x = x << 1;
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delay(1);
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}
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return x;
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}
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void fillRandom(unsigned char *x, size_t len) {
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setupLoRandom();
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size_t i;
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for (i = 0; i < len; i++) {
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x[i] = getLoRandomByte();
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}
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resetLoRa();
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}
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void fillRandom(unsigned char *x, size_t len, uint8_t except) {
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// used, for instance, when you want a non-zero value.
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// fillRandom(UUID, 16, 0);
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// get a UUID with 16 bytes, all non-zero
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setupLoRandom();
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size_t i;
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for (i = 0; i < len; i++) {
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unsigned char c = getLoRandomByte();
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while (c == except)c = getLoRandomByte();
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x[i] = c;
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}
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resetLoRa();
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}
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void fillRandom(unsigned char *x, size_t len, uint8_t minValue, uint8_t maxValue) {
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// used, for instance, when you want a value within a specified range.
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// fillRandom(x, 16, 0, 15);
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// get a bank of random numbers, between 0 and 15.
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setupLoRandom();
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size_t i;
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for (i = 0; i < len; i++) {
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unsigned char c = getLoRandomByte();
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while (c < minValue || c > maxValue)c = getLoRandomByte();
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x[i] = c;
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}
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resetLoRa();
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}
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void hexDump(unsigned char *buf, uint16_t len) {
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String s = "|", t = "| |";
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Serial.println(F(" |.0 .1 .2 .3 .4 .5 .6 .7 .8 .9 .a .b .c .d .e .f |"));
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Serial.println(F(" +------------------------------------------------+ +----------------+"));
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for (uint16_t i = 0; i < len; i += 16) {
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for (uint8_t j = 0; j < 16; j++) {
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if (i + j >= len) {
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s = s + " "; t = t + " ";
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} else {
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char c = buf[i + j];
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if (c < 16) s = s + "0";
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s = s + String(c, HEX) + " ";
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if (c < 32 || c > 127) t = t + ".";
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else t = t + (String(c));
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}
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}
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uint8_t index = i / 16;
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Serial.print(index, HEX); Serial.write('.');
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Serial.println(s + t + "|");
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s = "|"; t = "| |";
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}
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Serial.println(F(" +------------------------------------------------+ +----------------+"));
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}

‎README.md‎

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# LoRandom
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A library using Semtech's sx1276/7/8/9's `RegRssiWideband` register properly to generate random numbers. See [this issue](https://github.com/sandeepmistry/arduino-LoRa/issues/394) for context.
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This was written for Sandeep Mistry's library, but is easily adaptable to other platforms.
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See:
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![Generating Random Numbers with LoRandom](LoRandom.png)
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vs
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![Generating Random Numbers with LoRaClass::random](SandeepRandom.png)

‎keywords.txt‎

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#######################################
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# Syntax Coloring Map For LoRandom
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#######################################
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#######################################
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# Methods and Functions (KEYWORD2)
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#######################################
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setupLoRandom KEYWORD2
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writeRegister KEYWORD2
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readRegister KEYWORD2
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resetLoRa KEYWORD2
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getLoRandomByte KEYWORD2
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fillRandom KEYWORD2
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hexDump KEYWORD2
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RegOpMode LITERAL1
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RegModemConfig1 LITERAL1
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RegModemConfig2 LITERAL1
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RegRssiWideband LITERAL1

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