#include "fifo_declare.h"
-DECLARE_FIFO(uint8_t, uart_fifo, 128);
+DECLARE_FIFO(uint8_t, uart_fifo, 64);
+/*
+ * The method of "connecting" the the UART from external code is to use 4 IRQS.
+ * The easy one is UART->YOU, where you will be called with the byte everytime
+ * the AVR firmware sends one. Do whatever you like with it.
+ *
+ * The slightly more tricky one is the INPUT part. Since the AVR is quite a bit
+ * slower than your code most likely, there is a way for the AVR UART to tell
+ * you to "pause" sending it bytes when its own input buffer is full.
+ * So, the UART will send XON to you when its fifo is empty, XON means you can
+ * send as many bytes as you have until XOFF is sent. Note that these are two
+ * IRQs because you /will/ be called with XOFF when sending a byte in INPUT...
+ * So it's a reentrant process.
+ *
+ * When XOFF has been called, do not send any new bytes, they would be dropped.
+ * Instead wait for XON again and continue.
+ * See examples/parts/uart_udp.c for a full implementation
+ *
+ * Pseudo code:
+ *
+ * volatile int off = 0;
+ * void irq_xon()
+ * {
+ * off = 0;
+ * while (!off && bytes_left)
+ * avr_raise_irq(UART_IRQ_INPUT, a_byte);
+ * }
+ * void irq_xoff()
+ * {
+ * off = 1;
+ * }
+ *
+ */
enum {
UART_IRQ_INPUT = 0,
UART_IRQ_OUTPUT,
+ UART_IRQ_OUT_XON, // signaled (continuously) when input fifo is not full
+ UART_IRQ_OUT_XOFF, // signaled when input fifo IS full
UART_IRQ_COUNT
};
// add port number to get the real IRQ
#define AVR_IOCTL_UART_GETIRQ(_name) AVR_IOCTL_DEF('u','a','r',(_name))
+enum {
+ // the uart code monitors for firmware that pool on
+ // reception registers, and can do an atomic usleep()
+ // if it's detected, this helps regulating CPU
+ AVR_UART_FLAG_POOL_SLEEP = (1 << 0),
+ AVR_UART_FLAG_STDIO = (1 << 1), // print lines on the console
+};
+
typedef struct avr_uart_t {
avr_io_t io;
char name;
avr_regbit_t disabled; // bit in the PRR
- uint8_t r_udr;
- uint8_t r_ucsra;
- uint8_t r_ucsrb;
- uint8_t r_ucsrc;
+ avr_io_addr_t r_udr;
+ avr_io_addr_t r_ucsra;
+ avr_io_addr_t r_ucsrb;
+ avr_io_addr_t r_ucsrc;
avr_regbit_t rxen; // receive enabled
avr_regbit_t txen; // transmit enable
+ avr_regbit_t u2x; // double UART speed
+ avr_regbit_t usbs; // stop bits
+ avr_regbit_t ucsz; // data bits
+ avr_regbit_t ucsz2; // data bits, continued
- uint8_t r_ubrrl,r_ubrrh;
+ avr_io_addr_t r_ubrrl,r_ubrrh;
avr_int_vector_t rxc;
avr_int_vector_t txc;
avr_int_vector_t udrc;
uart_fifo_t input;
+
+ uint32_t flags;
+ avr_cycle_count_t usec_per_byte;
} avr_uart_t;
+/* takes a uint32_t* as parameter */
+#define AVR_IOCTL_UART_SET_FLAGS(_name) AVR_IOCTL_DEF('u','a','s',(_name))
+#define AVR_IOCTL_UART_GET_FLAGS(_name) AVR_IOCTL_DEF('u','a','g',(_name))
+
void avr_uart_init(avr_t * avr, avr_uart_t * port);
#endif /* AVR_UART_H_ */