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-rw-r--r--src/switch.cpp104
1 files changed, 104 insertions, 0 deletions
diff --git a/src/switch.cpp b/src/switch.cpp
new file mode 100644
index 0000000..2381640
--- /dev/null
+++ b/src/switch.cpp
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+#include "mbed.h"
+#include "Adafruit_SSD1306.h"
+
+//Switch input definition
+#define SW_PIN p22
+
+//Sampling period for the switch oscillator (us)
+#define SW_PERIOD 20000
+
+//Display interface pin definitions
+#define D_MOSI_PIN p5
+#define D_CLK_PIN p7
+#define D_DC_PIN p8
+#define D_RST_PIN p9
+#define D_CS_PIN p10
+
+//an SPI sub-class that sets up format and clock speed
+class SPIPreInit:public SPI {
+ public:
+ SPIPreInit(PinName mosi, PinName miso, PinName clk):SPI(mosi, miso, clk) {
+ format(8, 3);
+ frequency(2000000);
+ };
+};
+
+//Interrupt Service Routine prototypes (functions defined below)
+void sedge();
+void tout();
+
+//Output for the alive LED
+DigitalOut alive(LED1);
+
+//External interrupt input from the switch oscillator
+InterruptIn swin(SW_PIN);
+
+//Switch sampling timer
+Ticker swtimer;
+
+//Registers for the switch counter, switch counter latch register and update flag
+volatile uint16_t scounter = 0;
+volatile uint16_t scount = 0;
+volatile uint16_t update = 0;
+
+//Initialise SPI instance for communication with the display
+SPIPreInit gSpi(D_MOSI_PIN, NC, D_CLK_PIN); //MOSI,MISO,CLK
+
+//Initialise display driver instance
+Adafruit_SSD1306_Spi gOled1(gSpi, D_DC_PIN, D_RST_PIN, D_CS_PIN, 64, 128); //SPI,DC,RST,CS,Height,Width
+
+int main()
+{
+ //Initialisation
+ gOled1.setRotation(2); //Set display rotation
+
+ //Attach switch oscillator counter ISR to the switch input instance for a rising edge
+ swin.rise(&sedge);
+
+ //Attach switch sampling timer ISR to the timer instance with the required period
+ swtimer.attach_us(&tout, SW_PERIOD);
+
+ //Write some sample text
+ gOled1.printf("%ux%u OLED Display\r\n", gOled1.width(),
+ gOled1.height());
+
+ //Main loop
+ while (1) {
+ //Has the update flag been set?
+ if (update) {
+ //Clear the update flag
+ update = 0;
+
+ //Set text cursor
+ gOled1.setTextCursor(0, 0);
+
+ //Write the latest switch osciallor count
+ gOled1.printf("\n%05u ", scount);
+
+ //Copy the display buffer to the display
+ gOled1.display();
+
+ //Toggle the alive LED
+ alive = !alive;
+ }
+
+ }
+}
+
+//Interrupt Service Routine for rising edge on the switch oscillator input
+void sedge()
+{
+ //Increment the edge counter
+ scounter++;
+}
+
+//Interrupt Service Routine for the switch sampling timer
+void tout()
+{
+ //Read the edge counter into the output register
+ scount = scounter;
+ //Reset the edge counter
+ scounter = 0;
+ //Trigger a display update in the main loop
+ update = 1;
+}