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Corrected SPI CPOL/CPHA relationships

* Corrected CPOL/CPHA relationships

* Simplified to remove duplicated code

* Removed comments about when MISO is sampled. ESP seems to sample MISO on same clock edge as when MOSI is set.
Jason Follas 8 lat temu
rodzic
commit
e16204d4f4
1 zmienionych plików z 12 dodań i 5 usunięć
  1. 12 5
      app/driver/spi.c

+ 12 - 5
app/driver/spi.c

@@ -72,18 +72,25 @@ void spi_master_init(uint8 spi_no, unsigned cpol, unsigned cpha, uint32_t clock_
 
 	SET_PERI_REG_MASK(SPI_USER(spi_no), SPI_CS_SETUP|SPI_CS_HOLD|SPI_RD_BYTE_ORDER|SPI_WR_BYTE_ORDER|SPI_DOUTDIN);
 
-	//set clock polarity (Reference: http://bbs.espressif.com/viewtopic.php?f=49&t=1570)
+	// set clock polarity (Reference: http://bbs.espressif.com/viewtopic.php?f=49&t=1570)
+	// phase is dependent on polarity. See Issue #1161
 	if (cpol == 1) {
 		SET_PERI_REG_MASK(SPI_PIN(spi_no), SPI_IDLE_EDGE);
 	} else {
 		CLEAR_PERI_REG_MASK(SPI_PIN(spi_no), SPI_IDLE_EDGE);
 	}
-
+	
 	//set clock phase
-	if (cpha == 1) {
-		SET_PERI_REG_MASK(SPI_USER(spi_no), SPI_CK_OUT_EDGE|SPI_CK_I_EDGE);
+	if (cpha == cpol) {
+		// Mode 3: MOSI is set on falling edge of clock
+		// Mode 0: MOSI is set on falling edge of clock
+		CLEAR_PERI_REG_MASK(SPI_USER(spi_no), SPI_CK_OUT_EDGE);
+		SET_PERI_REG_MASK(SPI_USER(spi_no), SPI_CK_I_EDGE);
 	} else {
-    		CLEAR_PERI_REG_MASK(SPI_USER(spi_no), SPI_CK_OUT_EDGE|SPI_CK_I_EDGE);
+		// Mode 2: MOSI is set on rising edge of clock
+		// Mode 1: MOSI is set on rising edge of clock	
+		SET_PERI_REG_MASK(SPI_USER(spi_no), SPI_CK_OUT_EDGE);		
+		CLEAR_PERI_REG_MASK(SPI_USER(spi_no), SPI_CK_I_EDGE);
 	}
 
 	CLEAR_PERI_REG_MASK(SPI_USER(spi_no), SPI_FLASH_MODE|SPI_USR_MISO|SPI_USR_ADDR|SPI_USR_COMMAND|SPI_USR_DUMMY);