SPIFIFO - Interface for fast SPI usage!

teensy3/SPIFIFO.h

@@ -0,0 +1,111 @@
+
+#include "avr_emulation.h"
+
+#if F_BUS == 48000000
+
+#define SPI_CLOCK_24MHz   (SPI_CTAR_PBR(0) | SPI_CTAR_BR(0) | SPI_CTAR_DBR) //(48 / 2) * ((1+1)/2)
+#define SPI_CLOCK_16MHz   (SPI_CTAR_PBR(1) | SPI_CTAR_BR(0) | SPI_CTAR_DBR) //(48 / 3) * ((1+1)/2)  33% duty cycle
+#define SPI_CLOCK_12MHz   (SPI_CTAR_PBR(0) | SPI_CTAR_BR(0)) //(48 / 2) * ((1+0)/2)
+#define SPI_CLOCK_8MHz    (SPI_CTAR_PBR(1) | SPI_CTAR_BR(0)) //(48 / 3) * ((1+0)/2)
+#define SPI_CLOCK_6MHz    (SPI_CTAR_PBR(0) | SPI_CTAR_BR(1)) //(48 / 2) * ((1+0)/4)
+#define SPI_CLOCK_4MHz    (SPI_CTAR_PBR(1) | SPI_CTAR_BR(1)) //(48 / 3) * ((1+0)/4)
+
+#elif F_BUS == 24000000
+
+#define SPI_CLOCK_24MHz   (SPI_CTAR_PBR(0) | SPI_CTAR_BR(0) | SPI_CTAR_DBR) //(24 / 2) * ((1+1)/2)  12 MHz
+#define SPI_CLOCK_16MHz   (SPI_CTAR_PBR(0) | SPI_CTAR_BR(0) | SPI_CTAR_DBR) //(24 / 2) * ((1+1)/2)  12 MHz
+#define SPI_CLOCK_12MHz   (SPI_CTAR_PBR(0) | SPI_CTAR_BR(0) | SPI_CTAR_DBR) //(24 / 2) * ((1+1)/2)
+#define SPI_CLOCK_8MHz    (SPI_CTAR_PBR(1) | SPI_CTAR_BR(0) | SPI_CTAR_DBR) //(24 / 3) * ((1+1)/2)  33% duty cycle
+#define SPI_CLOCK_6MHz    (SPI_CTAR_PBR(0) | SPI_CTAR_BR(0)) //(24 / 2) * ((1+0)/2)
+#define SPI_CLOCK_4MHz    (SPI_CTAR_PBR(1) | SPI_CTAR_BR(0)) //(24 / 3) * ((1+0)/2)
+
+#endif
+
+// sck = F_BUS / PBR * ((1+DBR)/BR)
+//  PBR = 2, 3, 5, 7
+//  DBR = 0, 1         -- zero preferred
+//  BR = 2, 4, 6, 8, 16, 32, 64, 128, 256, 512
+
+#ifndef SPI_MODE0
+#define SPI_MODE0 0x00  // CPOL = 0, CPHA = 0
+#define SPI_MODE1 0x04  // CPOL = 0, CPHA = 1
+#define SPI_MODE2 0x08  // CPOL = 1, CPHA = 0
+#define SPI_MODE3 0x0C  // CPOL = 1, CPHA = 1
+#endif
+
+#define SPI_CONTINUE 1
+
+static uint8_t pcs=0;
+
+class SPIFIFOclass
+{
+public:
+	inline bool begin(uint8_t pin, uint32_t speed, uint32_t mode=SPI_MODE0) __attribute__((always_inline)) {
+		uint32_t p, ctar = speed;
+		SIM_SCGC6 |= SIM_SCGC6_SPI0;
+
+		SPI0_MCR = SPI_MCR_MSTR | SPI_MCR_MDIS | SPI_MCR_HALT | SPI_MCR_PCSIS(0x1F);
+		if (mode & 0x08) ctar |= SPI_CTAR_CPOL;
+		if (mode & 0x04) {
+			ctar |= SPI_CTAR_CPHA;
+			ctar |= (ctar & 0x0F) << 8;
+		} else {
+			ctar |= (ctar & 0x0F) << 12;
+		}
+		SPI0_CTAR0 = ctar | SPI_CTAR_FMSZ(7);
+		SPI0_CTAR1 = ctar | SPI_CTAR_FMSZ(15);
+		if (pin == 10) {         // PTC4
+			CORE_PIN10_CONFIG = PORT_PCR_MUX(2);
+			p = 0x01;
+		} else if (pin == 2) {   // PTD0
+			CORE_PIN2_CONFIG = PORT_PCR_MUX(2);
+			p = 0x01;
+		} else if (pin == 9) {   // PTC3
+			CORE_PIN9_CONFIG = PORT_PCR_MUX(2);
+			p = 0x02;
+		} else if (pin == 6) {   // PTD4
+			CORE_PIN6_CONFIG = PORT_PCR_MUX(2);
+			p = 0x02;
+		} else if (pin == 20) {  // PTD5
+			CORE_PIN20_CONFIG = PORT_PCR_MUX(2);
+			p = 0x04;
+		} else if (pin == 23) {  // PTC2
+			CORE_PIN23_CONFIG = PORT_PCR_MUX(2);
+			p = 0x04;
+		} else if (pin == 21) {  // PTD6
+			CORE_PIN21_CONFIG = PORT_PCR_MUX(2);
+			p = 0x08;
+		} else if (pin == 22) {  // PTC1
+			CORE_PIN22_CONFIG = PORT_PCR_MUX(2);
+			p = 0x08;
+		} else if (pin == 15) {  // PTC0
+			CORE_PIN15_CONFIG = PORT_PCR_MUX(2);
+			p = 0x10;
+		} else {
+			return false;
+		}
+		pcs = p;
+		clear();
+		SPCR.enable_pins();
+		return true;
+	}
+	inline void write(uint32_t b, uint32_t cont=0) __attribute__((always_inline)) {
+		while (((SPI0_SR) & (15 << 12)) > (3 << 12)) ; // wait for space in the TX fifo
+		SPI0_PUSHR = (b & 0xFF) | (pcs << 16) | (cont ? SPI_PUSHR_CONT : 0);
+	}
+	inline void write16(uint32_t b, uint32_t cont=0) __attribute__((always_inline)) {
+		while (((SPI0_SR) & (15 << 12)) > (3 << 12)) ; // wait for space in the TX fifo
+		SPI0_PUSHR = (b & 0xFFFF) | (pcs << 16) | (cont ? SPI_PUSHR_CONT : 0) | SPI_PUSHR_CTAS(1);
+	}
+	inline uint32_t read(void) __attribute__((always_inline)) {
+		while ((SPI0_SR & (15 << 4)) == 0) ;  // TODO, could wait forever
+		return SPI0_POPR;
+	}
+	inline void clear(void) __attribute__((always_inline)) {
+		SPI0_MCR = SPI_MCR_MSTR | SPI_MCR_PCSIS(0x1F) | SPI_MCR_CLR_TXF | SPI_MCR_CLR_RXF;
+	}
+};
+extern SPIFIFOclass SPIFIFO;
+
+
+

teensy3/avr_emulation.h

@@ -990,6 +990,7 @@ public:
 		if (pin == 14) pinout |= 4;
 	}
 	friend class SPSRemulation;
+	friend class SPIFIFOclass;
 private:
 	static inline void update_ctar(uint32_t ctar) __attribute__((always_inline)) {
 		if (SPI0_CTAR0 == ctar) return;