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/************************************************************************/
/* */
/* File: avr/usi.c */
/* Description: serial line device. */
/* Version: 1.0 */
/* Author: Otto Mattik */
/* */
/* (C)Copyright Otto Mattik 2014-2021. */
/* */
/* This file is a part of 'armen' (a tiny operating system). */
/* 'armen' is distributed under the CeCILL-V2.1 licence. For more */
/* details about this licence, please visit the website cecill.info */
/* */
/************************************************************************/
#ifndef AVR_UART_C
#error "do not use this code directly, it must be included via avr_uart.c"
#endif
#ifdef USE_PWM
#error "pwm and uart, used together, are incompatible"
#endif
/* TO DO: implement serial line via usi interface */
#include <avr/io.h>
#include <avr/interrupt.h>
/*
* this code is based on the AVR307 publication.
* it use the timer 1 (16 bits on ATtiny84, 8 bits on ATtiny85).
* the uart is configured with 8 data bits, no parity and 1 stop bit.
* the used pins are DI (input) and DO (output).
*/
#if defined(__AVR_ATtiny84__)
#define USI_INPUT_PIN PA6 /* receive */
#define USI_OUTPUT_PIN PA5 /* transmit */
#define USI_CONFIG_PINS() (\
PORTA |= (1<<USI_INPUT_PIN),\
DDRA = (DDRA\
| (1<<USI_OUTPUT_PIN))\
& ~(1<<USI_INPUT_PIN)\
)
#define USI_INPUT_START_BIT() (PINA & (1<<USI_INPUT_PIN) ? 0 : 1)
#define USI_CONFIG_TIMER(p) (\
TIMSK1 = 0, TCCR1A = 0,\
TCCR1B = (1<<ICNC1) | (p)\
)
#define USI_CONFIG_DEVICE() ()
#define USI_INPUT_CAPTURE_INT PCINT6_vect
#elif defined(__AVR_ATtiny85__)
#define USI_INPUT_PIN PB0 /* receive */
#define USI_OUTPUT_PIN PB1 /* transmit */
#define USI_CONFIG_PINS() (\
PORTB |= (1<<USI_INPUT_PIN),\
DDRB = (DDRB\
| (1<<USI_OUTPUT_PIN))\
& ~(1<<USI_INPUT_PIN)\
)
#define USI_INPUT_START_BIT() (PINB & (1<<USI_INPUT_PIN) ? 0 : 1)
#define USI_CONFIG_TIMER(p) (TIMSK = 0, TCCR1 = (p))
#define USI_CONFIG_DEVICE() ()
#define USI_INPUT_CAPTURE_INT PCINT0_vect
#else
#error "no or unavailable cpu defined"
#endif
#define USI_OVERFLOW_INTERRUPT USI_OVF_vect
#define TIMER_OVERFLOW_INTERRUPT TIMER1_OVF_vect
#define CONFIG_RS485(p) (CONFIG_RS485_DRIVER(), \
CONFIG_TIMER_PRESCALE(p), \
CONFIG_USI_DEVICE())
#define USI_RX_BUFFER_SIZE 16
#define UART_ECHOO_CHECK 0x40
/*
* reverse bits order lsb<->msb
*
* input:
* byte byte to reverse
* output:
* reversed byte
*/
static uint8_t reverse_byte( uint8_t byte )
{
byte = ((byte >> 1) & 0x55) | ((byte << 1) & 0xaa);
byte = ((byte >> 2) & 0x33) | ((byte << 2) & 0xcc);
byte = ((byte >> 4) & 0x0f) | ((byte << 4) & 0xf0);
return( byte );
}
/*
* initialize device
*
* input:
* device identifier (always 0)
* config uart configuration
* output:
* 0 if success, otherwise -1
*/
static int8_t uart_open( uint8_t device, uint8_t config )
{
return( -1 );
}
/*
* release device
*
* input:
* device identifier
* output:
* 0 if success, otherwise -1
*/
static int8_t uart_close( uint8_t device )
{
return( -1 );
}
/*
* read from device
*
* input:
* device identifier (always 0)
* byte address of byte to read
* output:
* 0 if success, otherwise -1
*/
static int8_t uart_read( uint8_t device, uint8_t* byte )
{
return( -1 );
}
/*
* write to device
*
* input:
* device identifier (always 0)
* byte byte to write
* output:
* 0 if success, otherwise -1
*/
static int8_t uart_write( uint8_t device, uint8_t byte )
{
return( -1 );
}
/*
* device special feature
*
* input:
* device identifier (always 0)
* request device dependent
* args list of arguments
* output:
* 0 if success, otherwise -1
*/
#ifdef UART_IOCTL
static int8_t uart_ioctl( uint8_t device, uint8_t request, va_list args )
{
return( -1 );
}
#endif
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