/** MIT-like-non-ai-license Copyright (c) 2024 Charles Lohr "CNLohr" Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the two following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. In addition the following restrictions apply: 1. The Software and any modifications made to it may not be used for the purpose of training or improving machine learning algorithms, including but not limited to artificial intelligence, natural language processing, or data mining. This condition applies to any derivatives, modifications, or updates based on the Software code. Any usage of the Software in an AI-training dataset is considered a breach of this License. 2. The Software may not be included in any dataset used for training or improving machine learning algorithms, including but not limited to artificial intelligence, natural language processing, or data mining. 3. Any person or organization found to be in violation of these restrictions will be subject to legal action and may be held liable for any damages resulting from such use. If any term is unenforcable, other terms remain in-force. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ // This file is code, but intended to be included into a .c file that // does #define's for a specific fitness. Below is an example .c file // that this could be included into to generate the bit table. It is // from an ESP8266 example, but other specifics can be specified on a // per-processor basis. /* const double center_frequency = 904.1; const double bw = .125; const uint32_t memory_offset = 0x20000; #define SF_NUMBER 7 #if SF_NUMBER < 7 #warning SF6 still does not work :( #endif #define SPI_DIV 1 // Funny modes: /// 80MHz, SF8, SPI_DIV 5 @903.9/904.1 produces hilarious mirror images around 904.0 #if MAIN_MHZ == 80 const double sample_rate = 1040.0/13.0/SPI_DIV; #if ( SF_NUMBER > 8 ) #error Not enough ram for chirp table #endif #elif MAIN_MHZ == 115 const double sample_rate = 1040.0/9.0/SPI_DIV; #if ( SF_NUMBER > 8 ) #error Not enough ram for chirp table #endif #elif MAIN_MHZ == 52 const double sample_rate = 1040.0/20.0/SPI_DIV; #if ( SF_NUMBER > 9 ) #error Not enough ram for chirp table #endif #elif MAIN_MHZ == 173 const double sample_rate = 1040.0/6.0/SPI_DIV; #if ( SF_NUMBER > 7 ) #error Not enough ram for chirp table #endif #else #error Unknown Clock Rate #endif EXTRA OPTIONS #define USE_16_BITS */ #include #include #include const double chirp_begin = center_frequency-bw/2; const double chirp_end = center_frequency+bw/2; #ifndef MEM_MAX_BYTES #define MEM_MAX_BYTES 2000000 #endif #ifndef SF_SYMBOL_TIME #define SF_SYMBOL_TIME 0.000001 #endif const double chirp_length_seconds = (8<= 1 ) { // When going off the top frequency, start over at the bottom. placeInSamples -= 1; } ////////////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////////////// // These are the key lines here. This is what actually decides the current // frequency and figures out what the given bit in a position should be. // I use 0.1 as an offset because it seems to have some beneficial behaviors // but 0.0 also seems to work really well. You can artifically reduce the // amplituide of the output signal by changing the offset in the comparison // on the last line of this section. double current_f = ( placeInSamples ) * ( fEnd - fStart ) + fStart; phase += 3.1415926 * 2.0 * current_f / sample_rate; int bit = sin( phase ) > 0.1; // HINT: if you want to mix multiple signals, add a DC offset here. ////////////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////////////// sample_word |= !!bit; samplect++; if( samplect == NUMBITS ) { #ifdef USE_16_BITS // sample_word = ((sample_word>>8)&0xff) | ((sample_word<<8)&0xff00); // sample_word = flipBits( sample_word, 16 ); fprintf( fcba, "0x%04x,%c", sample_word, ((words & 0xf) != 0xf)?' ':'\n' ); #else fprintf( fcba, "0x%08x,%c", sample_word, ((words & 0xf) != 0xf)?' ':'\n' ); #endif fwrite( &sample_word, 1, NUMBITS/8, fd ); words++; sample_word = 0; samplect = 0; if( samples < sampletotal ) words_nominal = words; if( samples >= sampletotal + bleedover*32 ) { break; } } sample_word <<= 1; } } } #ifndef ATTRIBUTE_FOR_DATA #define ATTRIBUTE_FOR_DATA #endif int gen_buffer_files() { fcba = fopen( "chirpbuff.h", "w" ); fd = fopen( "chirpbuff.dat", "w" ); fCBI = fopen( "chirpbuffinfo.h", "w" ); #ifdef USE_16_BITS fprintf( fcba, "const uint16_t chirpbuff[] " ATTRIBUTE_FOR_DATA " = {\n" ); #else fprintf( fcba, "const uint32_t chirpbuff[] " ATTRIBUTE_FOR_DATA " = {\n" ); #endif int quarter_chirp_length_bits = (int)(sampletotal/4.0+0.5); int factor = 0; int is_perfect_divisor = 0; int i; // DMA size words, when multiplied out should be SMALLER than the // overall length of our message, so that we can trim off the last few // words sometimes, to average out to the right bitrate. // So, we need to pick a number that when multiplied out, ends up // slightly larger than IDEAL_CHIRP_LENGTH_BITS. But not too much so. // First try to find a perfect divisor, if we can find a perfect divisor, // then no weird fixup stuff needs to be done. int seeking_perfect_divisor = 1; bleedover = 0; retry_without_seek: printf( "Searching for a divisor for %d\n", quarter_chirp_length_bits ); for( i = 511; i > 100; i-- ) { int nr_to_div = (quarter_chirp_length_bits / 32 + 32) / i; int num_bits_default = i * 32 * nr_to_div; int leftover = num_bits_default - quarter_chirp_length_bits; //fprintf( stderr, "%d %d %d [%d] --> %d\n", i, nr_to_div, num_bits_default, quarter_chirp_length_bits, leftover ); if( leftover < 32*nr_to_div && ( seeking_perfect_divisor ? (leftover == 0) : (leftover >= 0)) ) { // Make sure we aren't more than 1 32-bit word too large fprintf( stderr, "Found %s divisor: %d (%d - %d = %d)\n", (leftover == 0)?"PERFECT" : "OK", i, num_bits_default, quarter_chirp_length_bits, num_bits_default - quarter_chirp_length_bits ); factor = i; //XXX TODO: I think this bleedover calc is wrong. Should investigate? bleedover = num_bits_default/32; is_perfect_divisor = leftover == 0; break; } } if( seeking_perfect_divisor && !factor ) { seeking_perfect_divisor = 0; goto retry_without_seek; } if( !factor ) { fprintf( stderr, "Error: No factor of %d found, you may have to do something clever in rf_data_gen.c\n", quarter_chirp_length_bits ); return -9; } // For a given word, it is shifted out MSB (Bit and byte) first GenChirp( chirp_begin, chirp_end ); int sample_word_median = words; int quarter_chirp_length = ((words_nominal+2)/4); int reverse_start = words; words = 0; GenChirp( chirp_end, chirp_begin ); fprintf( fcba, "};\n" ); fclose( fcba ); fclose( fd ); #ifdef USE_16_BITS int bytes_total = 2*(words+sample_word_median); fprintf( stderr, "Wrote out %d uint16_t's.\n", words + sample_word_median ); #else int bytes_total = 4*(words+sample_word_median); fprintf( stderr, "Wrote out %d uint32_t's.\n", words + sample_word_median ); #endif if( bytes_total > MEM_MAX_BYTES ) { fprintf( stderr, "ERROR: Your table is too big (trying to write out %d bytes, please adjust SF/BW/clock rate settings)\n", bytes_total ); } fprintf( fCBI, "#define CHIRPLENGTH_WORDS (%d)\n", words_nominal ); fprintf( fCBI, "#define MEMORY_START_OFFSET_BYTES (0x%08x)\n", memory_offset ); fprintf( fCBI, "#define REVERSE_START_OFFSET_BYTES (0x%08x)\n", memory_offset + reverse_start * NUMBITS/8 ); fprintf( fCBI, "#define QUARTER_CHIRP_LENGTH_WORDS (%d)\n", (int)(quarter_chirp_length) ); fprintf( fCBI, "#define IDEAL_QUARTER_CHIRP_LENGTH_BITS (%d)\n", quarter_chirp_length_bits ); fprintf( fCBI, "#define CHIRPLENGTH_WORDS_WITH_PADDING (%d)\n", sample_word_median ); fprintf( fCBI, "#define STRIPE_BLEEDOVER_WORDS (%d)\n", bleedover ); fprintf( fCBI, "#define TARGET_SAMPLE_COUNT_BITS (%d)\n", (int)sampletotal ); fprintf( fCBI, "#define DMA_SIZE_WORDS (%d)\n", factor ); fprintf( fCBI, "#define NUM_DMAS_PER_QUARTER_CHIRP (%d)\n", quarter_chirp_length/factor+((is_perfect_divisor)?0:1) ); fprintf( fCBI, "#define SF_NUMBER %d\n", SF_NUMBER ); fprintf( fCBI, "#define SPI_DIV %d\n", SPI_DIV ); if( factor & 1 ) fprintf( fCBI, "#define DMA_SIZE_WORDS_DIVISIBLE_BY_TWO 0\n" ); else fprintf( fCBI, "#define DMA_SIZE_WORDS_DIVISIBLE_BY_TWO 1\n" ); if( factor & 3 ) fprintf( fCBI, "#define DMA_SIZE_WORDS_DIVISIBLE_BY_FOUR 0\n" ); else fprintf( fCBI, "#define DMA_SIZE_WORDS_DIVISIBLE_BY_FOUR 1\n" ); #ifdef USE_EXTERNAL_CLOCK fprintf( fCBI, "#define USE_EXTERNAL_CLOCK\n" ); #endif if( is_perfect_divisor ) fprintf( fCBI, "#define FOUND_PERFECT_DIVISOR\n" ); fclose( fCBI ); }