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- /*
- * WARNING: be careful changing this code, it is very timing dependent
- */
-
- #ifndef F_CPU
- #define F_CPU 16000000
- #endif
-
- #include <avr/io.h>
- #include <avr/interrupt.h>
- #include <util/delay.h>
- #include <stddef.h>
- #include <stdbool.h>
- #include "serial.h"
- //#include <pro_micro.h>
-
- #ifdef USE_SERIAL
- //#ifndef USE_SERIAL_PD2
-
- #ifndef SERIAL_USE_MULTI_TRANSACTION
- /* --- USE Simple API (OLD API, compatible with let's split serial.c) */
- #if SERIAL_SLAVE_BUFFER_LENGTH > 0
- uint8_t volatile serial_slave_buffer[SERIAL_SLAVE_BUFFER_LENGTH] = {0};
- #endif
- #if SERIAL_MASTER_BUFFER_LENGTH > 0
- uint8_t volatile serial_master_buffer[SERIAL_MASTER_BUFFER_LENGTH] = {0};
- #endif
- uint8_t volatile status0 = 0;
-
- SSTD_t transactions[] = {
- { (uint8_t *)&status0,
- #if SERIAL_MASTER_BUFFER_LENGTH > 0
- sizeof(serial_master_buffer), (uint8_t *)serial_master_buffer,
- #else
- 0, (uint8_t *)NULL,
- #endif
- #if SERIAL_SLAVE_BUFFER_LENGTH > 0
- sizeof(serial_slave_buffer), (uint8_t *)serial_slave_buffer
- #else
- 0, (uint8_t *)NULL,
- #endif
- }
- };
-
- void serial_master_init(void)
- { soft_serial_initiator_init(transactions); }
-
- void serial_slave_init(void)
- { soft_serial_target_init(transactions); }
-
- // 0 => no error
- // 1 => slave did not respond
- // 2 => checksum error
- int serial_update_buffers()
- { return soft_serial_transaction(); }
-
- #endif // Simple API (OLD API, compatible with let's split serial.c)
-
- #define ALWAYS_INLINE __attribute__((always_inline))
- #define NO_INLINE __attribute__((noinline))
- #define _delay_sub_us(x) __builtin_avr_delay_cycles(x)
-
- // Serial pulse period in microseconds.
- #define TID_SEND_ADJUST 14
-
- #define SELECT_SERIAL_SPEED 1
- #if SELECT_SERIAL_SPEED == 0
- // Very High speed
- #define SERIAL_DELAY 4 // micro sec
- #define READ_WRITE_START_ADJUST 33 // cycles
- #define READ_WRITE_WIDTH_ADJUST 3 // cycles
- #elif SELECT_SERIAL_SPEED == 1
- // High speed
- #define SERIAL_DELAY 6 // micro sec
- #define READ_WRITE_START_ADJUST 30 // cycles
- #define READ_WRITE_WIDTH_ADJUST 3 // cycles
- #elif SELECT_SERIAL_SPEED == 2
- // Middle speed
- #define SERIAL_DELAY 12 // micro sec
- #define READ_WRITE_START_ADJUST 30 // cycles
- #define READ_WRITE_WIDTH_ADJUST 3 // cycles
- #elif SELECT_SERIAL_SPEED == 3
- // Low speed
- #define SERIAL_DELAY 24 // micro sec
- #define READ_WRITE_START_ADJUST 30 // cycles
- #define READ_WRITE_WIDTH_ADJUST 3 // cycles
- #elif SELECT_SERIAL_SPEED == 4
- // Very Low speed
- #define SERIAL_DELAY 50 // micro sec
- #define READ_WRITE_START_ADJUST 30 // cycles
- #define READ_WRITE_WIDTH_ADJUST 3 // cycles
- #else
- #error Illegal Serial Speed
- #endif
-
-
- #define SERIAL_DELAY_HALF1 (SERIAL_DELAY/2)
- #define SERIAL_DELAY_HALF2 (SERIAL_DELAY - SERIAL_DELAY/2)
-
- #define SLAVE_INT_WIDTH_US 1
- #ifndef SERIAL_USE_MULTI_TRANSACTION
- #define SLAVE_INT_RESPONSE_TIME SERIAL_DELAY
- #else
- #define SLAVE_INT_ACK_WIDTH_UNIT 2
- #define SLAVE_INT_ACK_WIDTH 4
- #endif
-
- static SSTD_t *Transaction_table = NULL;
-
- inline static
- void serial_delay(void) {
- _delay_us(SERIAL_DELAY);
- }
-
- inline static
- void serial_delay_half1(void) {
- _delay_us(SERIAL_DELAY_HALF1);
- }
-
- inline static
- void serial_delay_half2(void) {
- _delay_us(SERIAL_DELAY_HALF2);
- }
-
- inline static void serial_output(void) ALWAYS_INLINE;
- inline static
- void serial_output(void) {
- SERIAL_PIN_DDR |= SERIAL_PIN_MASK;
- }
-
- // make the serial pin an input with pull-up resistor
- inline static void serial_input_with_pullup(void) ALWAYS_INLINE;
- inline static
- void serial_input_with_pullup(void) {
- SERIAL_PIN_DDR &= ~SERIAL_PIN_MASK;
- SERIAL_PIN_PORT |= SERIAL_PIN_MASK;
- }
-
- inline static
- uint8_t serial_read_pin(void) {
- return !!(SERIAL_PIN_INPUT & SERIAL_PIN_MASK);
- }
-
- inline static void serial_low(void) ALWAYS_INLINE;
- inline static
- void serial_low(void) {
- SERIAL_PIN_PORT &= ~SERIAL_PIN_MASK;
- }
-
- inline static void serial_high(void) ALWAYS_INLINE;
- inline static
- void serial_high(void) {
- SERIAL_PIN_PORT |= SERIAL_PIN_MASK;
- }
-
- void soft_serial_initiator_init(SSTD_t *sstd_table)
- {
- Transaction_table = sstd_table;
- serial_output();
- serial_high();
- }
-
- void soft_serial_target_init(SSTD_t *sstd_table)
- {
- Transaction_table = sstd_table;
- serial_input_with_pullup();
-
- #if SERIAL_PIN_MASK == _BV(PD0)
- // Enable INT0
- EIMSK |= _BV(INT0);
- // Trigger on falling edge of INT0
- EICRA &= ~(_BV(ISC00) | _BV(ISC01));
- #elif SERIAL_PIN_MASK == _BV(PD2)
- // Enable INT2
- EIMSK |= _BV(INT2);
- // Trigger on falling edge of INT2
- EICRA &= ~(_BV(ISC20) | _BV(ISC21));
- #else
- #error unknown SERIAL_PIN_MASK value
- #endif
- }
-
- // Used by the sender to synchronize timing with the reciver.
- static void sync_recv(void) NO_INLINE;
- static
- void sync_recv(void) {
- for (uint8_t i = 0; i < SERIAL_DELAY*5 && serial_read_pin(); i++ ) {
- }
- // This shouldn't hang if the target disconnects because the
- // serial line will float to high if the target does disconnect.
- while (!serial_read_pin());
- }
-
- // Used by the reciver to send a synchronization signal to the sender.
- static void sync_send(void)NO_INLINE;
- static
- void sync_send(void) {
- serial_low();
- serial_delay();
- serial_high();
- }
-
- // Reads a byte from the serial line
- static uint8_t serial_read_chunk(uint8_t *pterrcount, uint8_t bit) NO_INLINE;
- static uint8_t serial_read_chunk(uint8_t *pterrcount, uint8_t bit) {
- uint8_t byte, i, p, pb;
-
- _delay_sub_us(READ_WRITE_START_ADJUST);
- for( i = 0, byte = 0, p = 0; i < bit; i++ ) {
- serial_delay_half1(); // read the middle of pulses
- if( serial_read_pin() ) {
- byte = (byte << 1) | 1; p ^= 1;
- } else {
- byte = (byte << 1) | 0; p ^= 0;
- }
- _delay_sub_us(READ_WRITE_WIDTH_ADJUST);
- serial_delay_half2();
- }
- /* recive parity bit */
- serial_delay_half1(); // read the middle of pulses
- pb = serial_read_pin();
- _delay_sub_us(READ_WRITE_WIDTH_ADJUST);
- serial_delay_half2();
-
- *pterrcount += (p != pb)? 1 : 0;
-
- return byte;
- }
-
- // Sends a byte with MSB ordering
- void serial_write_chunk(uint8_t data, uint8_t bit) NO_INLINE;
- void serial_write_chunk(uint8_t data, uint8_t bit) {
- uint8_t b, p;
- for( p = 0, b = 1<<(bit-1); b ; b >>= 1) {
- if(data & b) {
- serial_high(); p ^= 1;
- } else {
- serial_low(); p ^= 0;
- }
- serial_delay();
- }
- /* send parity bit */
- if(p & 1) { serial_high(); }
- else { serial_low(); }
- serial_delay();
-
- serial_low(); // sync_send() / senc_recv() need raise edge
- }
-
- static void serial_send_packet(uint8_t *buffer, uint8_t size) NO_INLINE;
- static
- void serial_send_packet(uint8_t *buffer, uint8_t size) {
- for (uint8_t i = 0; i < size; ++i) {
- uint8_t data;
- data = buffer[i];
- sync_send();
- serial_write_chunk(data,8);
- }
- }
-
- static uint8_t serial_recive_packet(uint8_t *buffer, uint8_t size) NO_INLINE;
- static
- uint8_t serial_recive_packet(uint8_t *buffer, uint8_t size) {
- uint8_t pecount = 0;
- for (uint8_t i = 0; i < size; ++i) {
- uint8_t data;
- sync_recv();
- data = serial_read_chunk(&pecount, 8);
- buffer[i] = data;
- }
- return pecount == 0;
- }
-
- inline static
- void change_sender2reciver(void) {
- sync_send(); //0
- serial_delay_half1(); //1
- serial_low(); //2
- serial_input_with_pullup(); //2
- serial_delay_half1(); //3
- }
-
- inline static
- void change_reciver2sender(void) {
- sync_recv(); //0
- serial_delay(); //1
- serial_low(); //3
- serial_output(); //3
- serial_delay_half1(); //4
- }
-
- // interrupt handle to be used by the target device
- ISR(SERIAL_PIN_INTERRUPT) {
-
- #ifndef SERIAL_USE_MULTI_TRANSACTION
- serial_low();
- serial_output();
- SSTD_t *trans = Transaction_table;
- #else
- // recive transaction table index
- uint8_t tid;
- uint8_t pecount = 0;
- sync_recv();
- tid = serial_read_chunk(&pecount,4);
- if(pecount> 0)
- return;
- serial_delay_half1();
-
- serial_high(); // response step1 low->high
- serial_output();
- _delay_sub_us(SLAVE_INT_ACK_WIDTH_UNIT*SLAVE_INT_ACK_WIDTH);
- SSTD_t *trans = &Transaction_table[tid];
- serial_low(); // response step2 ack high->low
- #endif
-
- // target send phase
- if( trans->target2initiator_buffer_size > 0 )
- serial_send_packet((uint8_t *)trans->target2initiator_buffer,
- trans->target2initiator_buffer_size);
- // target switch to input
- change_sender2reciver();
-
- // target recive phase
- if( trans->initiator2target_buffer_size > 0 ) {
- if (serial_recive_packet((uint8_t *)trans->initiator2target_buffer,
- trans->initiator2target_buffer_size) ) {
- *trans->status = TRANSACTION_ACCEPTED;
- } else {
- *trans->status = TRANSACTION_DATA_ERROR;
- }
- } else {
- *trans->status = TRANSACTION_ACCEPTED;
- }
-
- sync_recv(); //weit initiator output to high
- }
-
- /////////
- // start transaction by initiator
- //
- // int soft_serial_transaction(int sstd_index)
- //
- // Returns:
- // TRANSACTION_END
- // TRANSACTION_NO_RESPONSE
- // TRANSACTION_DATA_ERROR
- // this code is very time dependent, so we need to disable interrupts
- #ifndef SERIAL_USE_MULTI_TRANSACTION
- int soft_serial_transaction(void) {
- SSTD_t *trans = Transaction_table;
- #else
- int soft_serial_transaction(int sstd_index) {
- SSTD_t *trans = &Transaction_table[sstd_index];
- #endif
- cli();
-
- // signal to the target that we want to start a transaction
- serial_output();
- serial_low();
- _delay_us(SLAVE_INT_WIDTH_US);
-
- #ifndef SERIAL_USE_MULTI_TRANSACTION
- // wait for the target response
- serial_input_with_pullup();
- _delay_us(SLAVE_INT_RESPONSE_TIME);
-
- // check if the target is present
- if (serial_read_pin()) {
- // target failed to pull the line low, assume not present
- serial_output();
- serial_high();
- *trans->status = TRANSACTION_NO_RESPONSE;
- sei();
- return TRANSACTION_NO_RESPONSE;
- }
-
- #else
- // send transaction table index
- sync_send();
- _delay_sub_us(TID_SEND_ADJUST);
- serial_write_chunk(sstd_index, 4);
- serial_delay_half1();
-
- // wait for the target response (step1 low->high)
- serial_input_with_pullup();
- while( !serial_read_pin() ) {
- _delay_sub_us(2);
- }
-
- // check if the target is present (step2 high->low)
- for( int i = 0; serial_read_pin(); i++ ) {
- if (i > SLAVE_INT_ACK_WIDTH + 1) {
- // slave failed to pull the line low, assume not present
- serial_output();
- serial_high();
- *trans->status = TRANSACTION_NO_RESPONSE;
- sei();
- return TRANSACTION_NO_RESPONSE;
- }
- _delay_sub_us(SLAVE_INT_ACK_WIDTH_UNIT);
- }
- #endif
-
- // initiator recive phase
- // if the target is present syncronize with it
- if( trans->target2initiator_buffer_size > 0 ) {
- if (!serial_recive_packet((uint8_t *)trans->target2initiator_buffer,
- trans->target2initiator_buffer_size) ) {
- serial_output();
- serial_high();
- *trans->status = TRANSACTION_DATA_ERROR;
- sei();
- return TRANSACTION_DATA_ERROR;
- }
- }
-
- // initiator switch to output
- change_reciver2sender();
-
- // initiator send phase
- if( trans->initiator2target_buffer_size > 0 ) {
- serial_send_packet((uint8_t *)trans->initiator2target_buffer,
- trans->initiator2target_buffer_size);
- }
-
- // always, release the line when not in use
- sync_send();
-
- *trans->status = TRANSACTION_END;
- sei();
- return TRANSACTION_END;
- }
-
- #ifdef SERIAL_USE_MULTI_TRANSACTION
- int soft_serial_get_and_clean_status(int sstd_index) {
- SSTD_t *trans = &Transaction_table[sstd_index];
- cli();
- int retval = *trans->status;
- *trans->status = 0;;
- sei();
- return retval;
- }
- #endif
-
- #endif
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