Merge branch 'master' of https://github.com/VictorLamoine/Arduino_STM32 into VictorLamoine-master

STM32F1/libraries/SPI/examples/spi_slave/spi_slave.ino

@@ -0,0 +1,37 @@
+// SPI full-duplex slave example
+// STM32 acts as a SPI slave and reads 8 bit data frames over SPI.
+// Master also gets a reply from the slave, which is a a simple count (0, 1, 2, 3)
+// that is incremented each time a data frame is received.
+// Serial output is here for debug
+
+#include <SPI.h>
+#include <cstdint>
+
+void setupSPI(void)
+{
+  // The clock value is not used
+  // SPI1 is selected by default
+  // MOSI, MISO, SCK and NSS PINs are set by the library
+  SPI.beginTransactionSlave(SPISettings(18000000, MSBFIRST, SPI_MODE0, DATA_SIZE_8BIT));
+}
+
+void setup()
+{
+  Serial.begin(115200);
+  delay(100);
+  setupSPI();
+}
+
+uint8_t count(0);
+void loop()
+{
+  // Blocking call to read SPI message
+  uint8_t msg = SPI.transfer(++count);
+  Serial.print("Received = 0b");
+  Serial.print(msg, BIN);
+  Serial.print(", 0x");
+  Serial.print(msg, HEX);
+  Serial.print(", ");
+  Serial.println(msg);
+}
+