kopia lustrzana https://github.com/markondej/fm_transmitter
Updated ReadMe and added minor tweaks
Marcin Kondej
rodzic
f0354b15ee
commit
56407e5fa3
17
README.md
17
README.md
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@ -1,8 +1,7 @@
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# fm_transmitter
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Use Raspberry Pi as FM transmitter. Works on any Raspberry Pi board.
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Use Raspberry Pi as FM transmitter. Works on every Raspberry Pi board.
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This project uses the general clock output to produce frequency modulated radio communication. It is based on idea originaly presented by [Oliver Mattos and Oskar Weigl](http://icrobotics.co.uk/wiki/index.php/Turning_the_Raspberry_Pi_Into_an_FM_Transmitter) on [PiFM project](http://icrobotics.co.uk/wiki/index.php/Turning_the_Raspberry_Pi_Into_an_FM_Transmitter).
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Just get an FM receiver and connect 20 - 40 cm plain wire to GPIO4 (PIN 7 on Raspberry Pi GPIO header) to act as an antena.
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## How to use it
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To use this project You will have to build it. First, clone this repository, then use "make" command as shown below:
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```
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@ -17,11 +16,11 @@ sudo ./fm_transmitter -f 102.0 acoustic_guitar_duet.wav
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Where:
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* -f frequency - Specifies the frequency in MHz, 100.0 by default if not passed
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* acoustic_guitar_duet.wav - Sample WAVE file, You can use your own
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Other options:
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* -d dma_channel - Specifies the used DMA channel (0 by default), pass 255 in order to disable DMA and use CPU
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* -d dma_channel - Specifies DMA channel to be used (0 by default), type 255 to disable DMA transfer, CPU will be used instead
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* -b bandwidth - Specifies the bandwidth in kHz, 100 by default
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* -r - Loops the playback
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After transmission has begun, simply tune an FM receiver to chosen frequency, You should hear the playback.
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### Supported audio formats
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You can transmitt uncompressed WAVE (.wav) files directly or read audio data from stdin, eg.:
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```
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@ -38,14 +37,12 @@ In order to use a USB microphone input use arecord command, eg.:
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arecord -D hw:1,0 -c1 -d 0 -r 22050 -f S16_LE | sudo ./fm_transmitter -f 100.6 -
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```
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In case of performance drop down use ```plughw:1,0``` instead of ```hw:1,0```.
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## Legal note
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Please keep in mind that transmitting on certain frequencies without special permissions may be illegal in your country.
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## New features
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* DMA peripheral support
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* works on any Raspberry Pi model
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* Allows custom frequency and bandwidth settings
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* works on every Raspberry Pi model
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* reads mono and stereo files
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* reads data from stdin
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Included sample audio was created by [graham_makes](https://freesound.org/people/graham_makes/sounds/449409/) and published on [freesound.org](https://freesound.org/)
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2
main.cpp
2
main.cpp
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@ -54,7 +54,7 @@ void sigIntHandler(int sigNum)
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int main(int argc, char** argv)
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{
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double frequency = 100.0;
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double bandwidth = 0.1;
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double bandwidth = 100.0;
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unsigned short dmaChannel = 0;
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bool loop = false;
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string filename;
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6
makefile
6
makefile
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@ -1,11 +1,11 @@
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EXECUTABLE = fm_transmitter
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VERSION = 0.9.1
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FLAGS = -Wall -fexceptions -pthread -O3 -fpermissive -fno-strict-aliasing
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FLAGS = -Wall -O3
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LIBS = -lm
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all: main.o mailbox.o error_reporter.o sample.o preemp.o wave_reader.o transmitter.o
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g++ $(FLAGS) -L/opt/vc/lib -lm -lbcm_host -o $(EXECUTABLE) main.o mailbox.o sample.o preemp.o error_reporter.o wave_reader.o transmitter.o
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g++ -L/opt/vc/lib -lm -lpthread -lbcm_host -o $(EXECUTABLE) main.o mailbox.o sample.o preemp.o error_reporter.o wave_reader.o transmitter.o
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mailbox.o: mailbox.c mailbox.h
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g++ $(FLAGS) -c mailbox.c
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@ -23,7 +23,7 @@ wave_reader.o: wave_reader.cpp wave_reader.h
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g++ $(FLAGS) -c wave_reader.cpp
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transmitter.o: transmitter.cpp transmitter.h
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g++ $(FLAGS) -I/opt/vc/include -c transmitter.cpp
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g++ $(FLAGS) -fno-strict-aliasing -I/opt/vc/include -c transmitter.cpp
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main.o: main.cpp
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g++ $(FLAGS) -DVERSION=\"$(VERSION)\" -DEXECUTABLE=\"$(EXECUTABLE)\" -c main.cpp
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@ -195,8 +195,8 @@ void Transmitter::play(WaveReader &reader, double frequency, double bandwidth, u
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}
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bool eof = samples->size() < bufferSize;
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unsigned clockDivisor = (unsigned)((500 << 12) / frequency + 0.5);
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unsigned divisorRange = (unsigned)((500 << 12) / (frequency + 0.5 * bandwidth) + 0.5) - clockDivisor;
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unsigned clockDivisor = (unsigned)round((500 << 12) / frequency);
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unsigned divisorRange = clockDivisor - (unsigned)round((500 << 12) / (frequency + 0.0005 * bandwidth));
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bool isError = false;
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string errorMessage;
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@ -206,7 +206,7 @@ void Transmitter::play(WaveReader &reader, double frequency, double bandwidth, u
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throw ErrorReporter("DMA channel number out of range (0 - 15)");
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}
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if (!allocateMemory(sizeof(unsigned) * ((bufferSize << 1) + 1) + sizeof(DMAControllBlock) * (bufferSize << 1))) {
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if (!allocateMemory(sizeof(unsigned) * ((2 * bufferSize) + 1) + sizeof(DMAControllBlock) * (2 * bufferSize))) {
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delete samples;
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throw ErrorReporter("Cannot allocate memory");
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}
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@ -246,8 +246,8 @@ void Transmitter::play(WaveReader &reader, double frequency, double bandwidth, u
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#endif
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volatile DMAControllBlock *dmaCb = (DMAControllBlock *)memAllocated;
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volatile unsigned *clkDiv = (unsigned *)memAllocated + ((sizeof(DMAControllBlock) / sizeof(unsigned)) << 1) * bufferSize;
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volatile unsigned *pwmFifoData = (unsigned *)memAllocated + (((sizeof(DMAControllBlock) / sizeof(unsigned)) << 1) + 1) * bufferSize;
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volatile unsigned *clkDiv = (unsigned *)memAllocated + 2 * (sizeof(DMAControllBlock) / sizeof(unsigned)) * bufferSize;
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volatile unsigned *pwmFifoData = (unsigned *)memAllocated + 2 * ((sizeof(DMAControllBlock) / sizeof(unsigned)) + 1) * bufferSize;
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for (i = 0; i < bufferSize; i++) {
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value = (*samples)[i].getMonoValue();
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#ifndef NO_PREEMP
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@ -280,7 +280,7 @@ void Transmitter::play(WaveReader &reader, double frequency, double bandwidth, u
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dma->cbAddress = getAddress(dmaCb);
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dma->ctlStatus = (0xFF << 16) | 0x01;
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usleep(BUFFER_TIME >> 2);
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usleep(BUFFER_TIME / 4);
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try {
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while (!eof && transmitting) {
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@ -295,7 +295,7 @@ void Transmitter::play(WaveReader &reader, double frequency, double bandwidth, u
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#ifndef NO_PREEMP
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value = preEmp.filter(value);
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#endif
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while (i == (((dma->cbAddress - getAddress(dmaCb)) / sizeof(DMAControllBlock)) >> 1)) {
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while (i == ((dma->cbAddress - getAddress(dmaCb)) / (2 *sizeof(DMAControllBlock)))) {
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usleep(1);
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}
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clkDiv[i] = (0x5A << 24) | (clockDivisor - (int)round(value * divisorRange));
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@ -309,11 +309,8 @@ void Transmitter::play(WaveReader &reader, double frequency, double bandwidth, u
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isError = true;
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}
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if (eof || isError) {
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dmaCb[cbIndex].nextCbAddress = 0x00;
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} else {
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dmaCb[(bufferSize - 1) << 1].nextCbAddress = 0x00;
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}
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cbIndex -= 2;
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dmaCb[cbIndex].nextCbAddress = 0x00;
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while (dma->cbAddress != 0x00) {
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usleep(1);
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}
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@ -348,7 +345,7 @@ void Transmitter::play(WaveReader &reader, double frequency, double bandwidth, u
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throw ErrorReporter(oss.str());
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}
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usleep(BUFFER_TIME >> 1);
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usleep(BUFFER_TIME / 2);
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try {
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while (!eof && transmitting) {
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@ -363,7 +360,7 @@ void Transmitter::play(WaveReader &reader, double frequency, double bandwidth, u
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eof = samples->size() < bufferSize;
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buffer = samples;
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}
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usleep(BUFFER_TIME >> 1);
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usleep(BUFFER_TIME / 2);
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}
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}
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catch (ErrorReporter &error) {
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