108 lines
2.9 KiB
C++
108 lines
2.9 KiB
C++
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/* The ESP32 has four SPi buses, however as of right now only two of
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* them are available to use, HSPI and VSPI. Simply using the SPI API
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* as illustrated in Arduino examples will use VSPI, leaving HSPI unused.
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*
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* However if we simply intialise two instance of the SPI class for both
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* of these buses both can be used. However when just using these the Arduino
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* way only will actually be outputting at a time.
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*
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* Logic analyser capture is in the same folder as this example as
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* "multiple_bus_output.png"
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*
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* created 30/04/2018 by Alistair Symonds
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*/
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#include <SPI.h>
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// Define ALTERNATE_PINS to use non-standard GPIO pins for SPI bus
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#ifdef ALTERNATE_PINS
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#define VSPI_MISO 2
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#define VSPI_MOSI 4
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#define VSPI_SCLK 0
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#define VSPI_SS 33
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#define HSPI_MISO 26
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#define HSPI_MOSI 27
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#define HSPI_SCLK 25
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#define HSPI_SS 32
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#else
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#define VSPI_MISO MISO
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#define VSPI_MOSI MOSI
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#define VSPI_SCLK SCK
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#define VSPI_SS SS
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#define HSPI_MISO 12
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#define HSPI_MOSI 13
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#define HSPI_SCLK 14
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#define HSPI_SS 15
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#endif
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static const int spiClk = 1000000; // 1 MHz
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//uninitalised pointers to SPI objects
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SPIClass * vspi = NULL;
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SPIClass * hspi = NULL;
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void setup() {
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//initialise two instances of the SPIClass attached to VSPI and HSPI respectively
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vspi = new SPIClass(VSPI);
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hspi = new SPIClass(HSPI);
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//clock miso mosi ss
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#ifndef ALTERNATE_PINS
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//initialise vspi with default pins
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//SCLK = 18, MISO = 19, MOSI = 23, SS = 5
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vspi->begin();
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#else
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//alternatively route through GPIO pins of your choice
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vspi->begin(VSPI_SCLK, VSPI_MISO, VSPI_MOSI, VSPI_SS); //SCLK, MISO, MOSI, SS
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#endif
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#ifndef ALTERNATE_PINS
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//initialise hspi with default pins
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//SCLK = 14, MISO = 12, MOSI = 13, SS = 15
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hspi->begin();
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#else
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//alternatively route through GPIO pins
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hspi->begin(HSPI_SCLK, HSPI_MISO, HSPI_MOSI, HSPI_SS); //SCLK, MISO, MOSI, SS
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#endif
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//set up slave select pins as outputs as the Arduino API
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//doesn't handle automatically pulling SS low
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pinMode(VSPI_SS, OUTPUT); //VSPI SS
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pinMode(HSPI_SS, OUTPUT); //HSPI SS
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}
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// the loop function runs over and over again until power down or reset
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void loop() {
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//use the SPI buses
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vspiCommand();
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hspiCommand();
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delay(100);
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}
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void vspiCommand() {
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byte data = 0b01010101; // junk data to illustrate usage
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//use it as you would the regular arduino SPI API
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vspi->beginTransaction(SPISettings(spiClk, MSBFIRST, SPI_MODE0));
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digitalWrite(VSPI_SS, LOW); //pull SS slow to prep other end for transfer
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vspi->transfer(data);
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digitalWrite(VSPI_SS, HIGH); //pull ss high to signify end of data transfer
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vspi->endTransaction();
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}
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void hspiCommand() {
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byte stuff = 0b11001100;
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hspi->beginTransaction(SPISettings(spiClk, MSBFIRST, SPI_MODE0));
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digitalWrite(HSPI_SS, LOW);
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hspi->transfer(stuff);
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digitalWrite(HSPI_SS, HIGH);
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hspi->endTransaction();
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}
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