Added SPI support file

Makefile

@@ -28,6 +28,7 @@ BINARY = main
 OBJS  = $(BINARY).o
 OBJS += lib/usart.o
 OBJS += lib/iopins.o
+OBJS += lib/spi.o
 
 # Dirs with header files
 INCL_DIRS = . lib/

avr-c-bp.pro

@@ -18,12 +18,15 @@ DISTFILES += \
 HEADERS += \
 	lib/calc.h \
 	lib/iopins.h \
-	lib/usart.h
+	lib/usart.h \
+    lib/nsdelay.h \
+    lib/spi.h
 
 SOURCES += \
 	lib/iopins.c \
 	main.c \
-    lib/usart.c
+    lib/usart.c \
+    lib/spi.c
 
 # === Flags for the Clang code model===
 #

lib/calc.h

@@ -10,7 +10,7 @@
 // --- Increment in range ---
 // when overflown, wraps within range. Lower bound < upper bound.
 // ..., upper bound excluded
-#define inc_wrap(var, min, max)  { if ((var) >= (max - 1)) { (var) = (min); } else { (var)++; } }
+#define inc_wrap(var, min, max)  do { if ((var) >= (max - 1)) { (var) = (min); } else { (var)++; } } while(0)
 // ..., upper bound included
 #define inc_wrapi(var, min, max) inc_wrap((var), (min), (max) + 1)
 
@@ -18,7 +18,7 @@
 // --- Decrement in range ---
 // when underflown, wraps within range. Lower bound < upper bound.
 // ..., upper bound excluded
-#define dec_wrap(var, min, max)  { if ((var) <= (min)) { (var) = (max) - 1; } else { (var)--; } }
+#define dec_wrap(var, min, max)  do { if ((var) <= (min)) { (var) = (max) - 1; } else { (var)--; } } while(0)
 // ..., upper bound included
 #define dec_wrapi(var, min, max) dec_wrap((var), (min), (max) + 1)
 
@@ -26,31 +26,31 @@
 // --- Bit manipulation --
 
 // Set bit
-#define sbi(reg, bit) { (reg) |=  (1 << (uint8_t)(bit)); }
+#define sbi(reg, bit) do { (reg) |=  (1 << (uint8_t)(bit)); } while(0)
 
 // Clear bit
-#define cbi(reg, bit) { (reg) &= ~(1 << (uint8_t)(bit)); }
+#define cbi(reg, bit) do { (reg) &= ~(1 << (uint8_t)(bit)); } while(0)
 
 // Get n-th bit
-#define get_bit(reg, bit) (((reg) >> (uint8_t)(bit)) & 0x1)
+#define get_bit(reg, bit) ((bool)((reg) >> (uint8_t)(bit)))
 
-// Test n-th bit (Can't use bit_is_set, as it's redefined in sfr_def.h)
+// Test n-th bit (Can't use bit_is_set, as it's defined in sfr_def.h)
 #define bit_is_high(reg, bit) get_bit(reg, bit)
 #define bit_is_low(reg, bit)  (!get_bit(reg, bit))
 
 // Write value to n-th bit
-#define set_bit(reg, bit, value) { (reg) = ((reg) & ~(1 << (uint8_t)(bit))) | (((uint8_t)(value) & 0x1) << (uint8_t)(bit)); }
+#define set_bit(reg, bit, value) do { (reg) = ((reg) & ~(1 << (uint8_t)(bit))) | (((uint8_t)(bool)(value)) << (uint8_t)(bit)); } while(0)
 
 // Invert n-th bit
-#define toggle_bit(reg, bit) { (reg) ^= (1 << (uint8_t)(bit)); }
+#define toggle_bit(reg, bit) do { (reg) ^= (1 << (uint8_t)(bit)); } while(0)
 
 
 // --- Bit manipulation with pointer to variable ---
 
 // Set n-th bit in pointee
-#define sbi_p(reg_p, bit) { (*(reg_p)) |=  (1 << (uint8_t)(bit)); }
+#define sbi_p(reg_p, bit) do { (*(reg_p)) |=  (1 << (uint8_t)(bit)); } while(0)
 // Clear n-th bit in pointee
-#define cbi_p(reg_p, bit) { (*(reg_p)) &= ~(1 << (uint8_t)(bit)); }
+#define cbi_p(reg_p, bit) do { (*(reg_p)) &= ~(1 << (uint8_t)(bit)); } while(0)
 
 // Get n-th bit in pointee
 #define get_bit_p(reg_p, bit) ((*(reg_p) >> (uint8_t)(bit)) & 0x1)
@@ -60,18 +60,18 @@
 #define bit_is_low_p(reg_p, bit)  (!get_bit_p(reg_p, bit))
 
 // Write value to a bit in pointee
-#define set_bit_p(reg_p, bit, value) { *(reg_p) = (*(reg_p) & ~(1 << ((uint8_t)(bit) & 0x1))) | (((uint8_t)(value) & 0x1) << (uint8_t)(bit)); }
+#define set_bit_p(reg_p, bit, value) do { *(reg_p) = (*(reg_p) & ~(1 << ((uint8_t)(bool)(bit)))) | (((uint8_t)(bool)(value)) << (uint8_t)(bit)); } while(0)
-#define toggle_bit_p(reg_p, bit)     { *(reg_p) ^= (1 << (uint8_t)(bit)); }
+#define toggle_bit_p(reg_p, bit)     do { *(reg_p) ^= (1 << (uint8_t)(bit)); } while(0)
 
 
 // --- Nibble manipulation ---
 
 // Replace nibble in a byte
-#define set_low_nibble(reg, value)  { (reg) = ((reg) & 0xF0) | ((uint8_t)(value) & 0xF); }
+#define set_low_nibble(reg, value)  do { (reg) = ((reg) & 0xF0) | ((uint8_t)(value) & 0xF); } while(0)
-#define set_high_nibble(reg, value) { (reg) = ((reg) & 0x0F) | (((uint8_t)(value) & 0xF) << 4); }
+#define set_high_nibble(reg, value) do { (reg) = ((reg) & 0x0F) | (((uint8_t)(value) & 0xF) << 4); } while(0)
 
-#define set_low_nibble_p(reg_p, value)  { *(reg_p) = (*(reg_p) & 0xF0) | ((uint8_t)(value) & 0xF); }
+#define set_low_nibble_p(reg_p, value)  do { *(reg_p) = (*(reg_p) & 0xF0) | ((uint8_t)(value) & 0xF); } while(0)
-#define set_high_nibble_p(reg_p, value) { *(reg_p) = (*(reg_p) & 0x0F) | (((uint8_t)(value) & 0xF) << 4); }
+#define set_high_nibble_p(reg_p, value) do { *(reg_p) = (*(reg_p) & 0x0F) | (((uint8_t)(value) & 0xF) << 4); } while(0)
 
 #define low_nibble(x) ((uint8_t)(x) & 0xF)
 #define high_nibble(x) (((uint8_t)(x) & 0xF0) >> 4)

lib/spi.c

@@ -0,0 +1,62 @@
+#include <avr/io.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "iopins.h"
+#include "spi.h"
+
+
+/** Init SPI (for SD card communication) */
+void spi_init_master(enum SPI_order order, enum SPI_cpol cpol, enum SPI_cpha cpha, enum SPI_clk_div clkdiv)
+{
+	as_output(PIN_SS); // SS output - we control slave
+	as_output(PIN_MOSI); // MOSI output - we talk to slave
+	as_output(PIN_SCK); // SCK output - we're generating clock
+	// MISO is configured automatically as input
+
+	SPCR = 0;
+	SPCR |= (1 << MSTR);
+	SPCR |= (order << DORD);
+	SPCR |= (cpol << CPOL);
+	SPCR |= (cpha << CPHA);
+
+	// speed
+	SPCR |= (clkdiv & 0b11);
+	SPSR = (bool)(clkdiv & 0b100); // write SPI2X flag
+
+	// enable SPI
+	SPCR |= (1 << SPE);
+}
+
+
+/** Init SPI (for SD card communication) */
+void spi_init_slave(enum SPI_order order, enum SPI_cpol cpol, enum SPI_cpha cpha)
+{
+	as_output(PIN_MISO); // we're listening to master
+	// MOSI, SS, SCK are configured automatically
+
+	SPCR = 0;
+	SPCR |= (order << DORD);
+	SPCR |= (cpol << CPOL);
+	SPCR |= (cpha << CPHA);
+
+	// enable SPI
+	SPCR |= (1 << SPE);
+}
+
+/** Write a byte to SPI. Returns received byte. */
+uint8_t spi_send(uint8_t byte)
+{
+	SPDR = byte;
+	while (bit_is_low(SPSR, SPIF));
+
+	return SPDR;
+}
+
+/** Receive (as slave). Blocking. */
+uint8_t spi_receive(uint8_t reply)
+{
+	SPDR = reply;
+	while (bit_is_low(SPSR, SPIF));
+	return SPDR;
+}

lib/spi.h

@@ -0,0 +1,69 @@
+#pragma once
+
+#include <avr/io.h>
+#include <stdint.h>
+
+#include "calc.h"
+#include "iopins.h"
+
+#define PIN_MISO 12
+#define PIN_MOSI 11
+#define PIN_SCK 13
+#define PIN_SS 10
+
+/** Bit order */
+enum SPI_order {
+	SPI_LSB_FIRST = 0,
+	SPI_MSB_FIRST = 1
+};
+
+/** Clock polarity */
+enum SPI_cpol {
+	CPOL_0 = 0,
+	CPOL_1 = 1
+};
+
+/** Clock phase */
+enum SPI_cpha {
+	CPHA_0 = 0,
+	CPHA_1 = 1
+};
+
+/** Clock prescaller <SPI2X><SPR1><SPR0> */
+enum SPI_clk_div {
+	SPI_DIV_2   = 0b100, // 2x (master only, can't receive at this speed)
+	SPI_DIV_4   = 0b000,
+	SPI_DIV_8   = 0b101, // 2x
+	SPI_DIV_16  = 0b001,
+	SPI_DIV_32  = 0b110, // 2x
+	SPI_DIV_64  = 0b010,
+	SPI_DIV_128 = 0b011
+};
+
+
+/** Set SS to active state (LOW) */
+#define spi_ss_enable()  pin_down(PIN_SS)
+
+
+/** Set SS to disabled state (HIGH) */
+#define spi_ss_disable() pin_up(PIN_SS)
+
+
+/** Enable SPI ISR */
+#define spi_isr_enable(yes) set_bit(SPCR, SPIE, yes)
+
+
+/** Init SPI (for SD card communication) */
+void spi_init_master(enum SPI_order order, enum SPI_cpol cpol, enum SPI_cpha cpha, enum SPI_clk_div clkdiv);
+
+
+/** Init SPI (for SD card communication) */
+void spi_init_slave(enum SPI_order order, enum SPI_cpol cpol, enum SPI_cpha cpha);
+
+
+/** Write a byte to SPI. Returns received byte. */
+uint8_t spi_send(uint8_t byte);
+
+
+/** Receive (as slave). Blocking. */
+uint8_t spi_receive(uint8_t reply);

lib/usart.c

@@ -66,7 +66,7 @@ void usart_puts_P(const char* str)
 
 
 /** Clear receive buffer */
-void usart_clear_rx(void)
+void usart_flush_rx(void)
 {
 	uint8_t dummy;
 	while (bit_is_high(UCSR0A, RXC0))

lib/usart.h

@@ -32,28 +32,28 @@ enum {
 	BAUD_1M = 0,
 };
 
-/** Init UART with a UBRR value */
+/** Init UART with a UBRR value - can use the BAUD_* constants for 16 MHz */
 void usart_init(uint16_t ubrr);
 
 /** Check if there's a byte in the RX register */
-#define usart_rx_ready() (0 != (UCSR0A & (1 << RXC0)))
+#define usart_rx_ready() bit_is_high(UCSR0A, RXC0)
 
-/** Check if transmission of everything is done */
+/** Check if USART is ready to accept new byte to send */
-#define usart_tx_ready() (0 != (UCSR0A & (1 << UDRE0)))
+#define usart_tx_ready() bit_is_low(UCSR0A, UDRE0)
 
 
 // ---- Enable UART interrupts ------------
 
 /** Enable or disable RX ISR */
-#define usart_rx_isr_enable(yes) set_bit(UCSR0B, RXCIE0, (yes))
+#define usart_isr_rx_enable(yes) set_bit(UCSR0B, RXCIE0, (yes))
 
 
-/** Enable or disable TX ISR (1 byte is sent) */
+/** Enable or disable TX ISR (all data sent) */
-#define usart_tx_isr_enable(yes) set_bit(UCSR0B, TXCIE0, (yes))
+#define usart_isr_tx_enable(yes) set_bit(UCSR0B, TXCIE0, (yes))
 
 
-/** Enable or disable DRE ISR (all is sent) */
+/** Enable or disable DRE ISR (data register empty) */
-#define usart_dre_isr_enable(yes) set_bit(UCSR0B, UDRIE0, (yes))
+#define usart_isr_dre_enable(yes) set_bit(UCSR0B, UDRIE0, (yes))
 
 
 // ---- Basic IO --------------------------
@@ -66,12 +66,8 @@ void usart_tx(uint8_t data);
 uint8_t usart_rx(void);
 
 
-/** Send byte over UART */
-#define usart_putc(data) usart_tx((data))
-
-
 /** Clear receive buffer */
-void usart_clear_rx(void);
+void usart_flush_rx(void);
 
 
 // ---- Strings ---------------------------
@@ -80,5 +76,5 @@ void usart_clear_rx(void);
 void usart_puts(const char* str);
 
 
-/** Send progmem string over UART */
+/** Send progmem string `PSTR("foobar")` over UART  */
 void usart_puts_P(const char* str);

main.c

@@ -27,7 +27,7 @@ ISR(USART_RX_vect)
 void main()
 {
 	usart_init(BAUD_9600);
-	usart_rx_isr_enable(true); // enable RX interrupt handler
+	usart_isr_rx_enable(true); // enable RX interrupt handler
 
 	// configure pins
 	as_output(LED);