#ifdef USE_SERIAL
-// Serial pulse period in microseconds. Its probably a bad idea to lower this
-// value.
-#define SERIAL_DELAY 30
+#define _delay_sub_us(x) __builtin_avr_delay_cycles(x)
+
+// Serial pulse period in microseconds.
+#define SELECT_SERIAL_SPEED 1
+#if SELECT_SERIAL_SPEED == 0
+ // Very High speed
+ #define SERIAL_DELAY 4 // micro sec
+ #define READ_WRITE_START_ADJUST 30 // cycles
+ #define READ_WRITE_WIDTH_ADJUST 10 // cycles
+#elif SELECT_SERIAL_SPEED == 1
+ // High speed
+ #define SERIAL_DELAY 6 // micro sec
+ #define READ_WRITE_START_ADJUST 23 // cycles
+ #define READ_WRITE_WIDTH_ADJUST 10 // cycles
+#elif SELECT_SERIAL_SPEED == 2
+ // Middle speed
+ #define SERIAL_DELAY 12 // micro sec
+ #define READ_WRITE_START_ADJUST 25 // cycles
+ #define READ_WRITE_WIDTH_ADJUST 10 // cycles
+#elif SELECT_SERIAL_SPEED == 3
+ // Low speed
+ #define SERIAL_DELAY 24 // micro sec
+ #define READ_WRITE_START_ADJUST 25 // cycles
+ #define READ_WRITE_WIDTH_ADJUST 10 // cycles
+#elif SELECT_SERIAL_SPEED == 4
+ // Very Low speed
+ #define SERIAL_DELAY 50 // micro sec
+ #define READ_WRITE_START_ADJUST 25 // cycles
+ #define READ_WRITE_WIDTH_ADJUST 10 // 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 1
+#define SLAVE_INT_RESPONSE_TIME SERIAL_DELAY
uint8_t volatile serial_slave_buffer[SERIAL_SLAVE_BUFFER_LENGTH] = {0};
uint8_t volatile serial_master_buffer[SERIAL_MASTER_BUFFER_LENGTH] = {0};
void serial_delay(void) {
_delay_us(SERIAL_DELAY);
}
-void serial_delay_short(void) {
- _delay_us(SERIAL_DELAY-1);
+
+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) {
SERIAL_PIN_DDR |= SERIAL_PIN_MASK;
// make the serial pin an input with pull-up resistor
inline static
-void serial_input(void) {
+void serial_input_with_pullup(void) {
SERIAL_PIN_DDR &= ~SERIAL_PIN_MASK;
SERIAL_PIN_PORT |= SERIAL_PIN_MASK;
}
}
void serial_slave_init(void) {
- serial_input();
+ serial_input_with_pullup();
#ifndef USE_SERIAL_PD2
// Enable INT0
#endif
}
-// Used by the master to synchronize timing with the slave.
+// Used by the sender to synchronize timing with the reciver.
static
void sync_recv(void) {
- serial_input();
+ for (int i = 0; i < SERIAL_DELAY*5 && serial_read_pin(); i++ ) {
+ }
// This shouldn't hang if the slave disconnects because the
// serial line will float to high if the slave does disconnect.
while (!serial_read_pin());
- //serial_delay();
- _delay_us(SERIAL_DELAY-5);
}
-// Used by the slave to send a synchronization signal to the master.
+// Used by the reciver to send a synchronization signal to the sender.
static
void sync_send(void) {
- serial_output();
-
serial_low();
serial_delay();
-
serial_high();
}
static
uint8_t serial_read_byte(void) {
uint8_t byte = 0;
- serial_input();
+ _delay_sub_us(READ_WRITE_START_ADJUST);
for ( uint8_t i = 0; i < 8; ++i) {
+ serial_delay_half1(); // read the middle of pulses
byte = (byte << 1) | serial_read_pin();
- serial_delay();
- _delay_us(1);
+ _delay_sub_us(READ_WRITE_WIDTH_ADJUST);
+ serial_delay_half2();
}
-
return byte;
}
// Sends a byte with MSB ordering
static
void serial_write_byte(uint8_t data) {
- uint8_t b = 8;
- serial_output();
- while( b-- ) {
- if(data & (1 << b)) {
+ uint8_t b = 1<<7;
+ while( b ) {
+ if(data & b) {
serial_high();
} else {
serial_low();
}
+ b >>= 1;
serial_delay();
}
+ serial_low(); // sync_send() / senc_recv() need raise edge
}
// interrupt handle to be used by the slave device
ISR(SERIAL_PIN_INTERRUPT) {
- sync_send();
+ serial_output();
+ // slave send phase
uint8_t checksum = 0;
for (int i = 0; i < SERIAL_SLAVE_BUFFER_LENGTH; ++i) {
- serial_write_byte(serial_slave_buffer[i]);
sync_send();
+ serial_write_byte(serial_slave_buffer[i]);
checksum += serial_slave_buffer[i];
}
- serial_write_byte(checksum);
sync_send();
+ serial_write_byte(checksum);
- // wait for the sync to finish sending
- serial_delay();
-
- // read the middle of pulses
- _delay_us(SERIAL_DELAY/2);
+ // slave switch to input
+ sync_send(); //0
+ serial_delay_half1(); //1
+ serial_low(); //2
+ serial_input_with_pullup(); //2
+ serial_delay_half1(); //3
+ // slave recive phase
uint8_t checksum_computed = 0;
for (int i = 0; i < SERIAL_MASTER_BUFFER_LENGTH; ++i) {
+ sync_recv();
serial_master_buffer[i] = serial_read_byte();
- sync_send();
checksum_computed += serial_master_buffer[i];
}
+ sync_recv();
uint8_t checksum_received = serial_read_byte();
- sync_send();
-
- serial_input(); // end transaction
if ( checksum_computed != checksum_received ) {
status |= SLAVE_DATA_CORRUPT;
} else {
status &= ~SLAVE_DATA_CORRUPT;
}
+
+ sync_recv(); //weit master output to high
}
inline
// Returns:
// 0 => no error
// 1 => slave did not respond
+// 2 => checksum error
int serial_update_buffers(void) {
// this code is very time dependent, so we need to disable interrupts
cli();
// signal to the slave that we want to start a transaction
serial_output();
serial_low();
- _delay_us(1);
+ _delay_us(SLAVE_INT_WIDTH);
// wait for the slaves response
- serial_input();
- serial_high();
- _delay_us(SERIAL_DELAY);
+ serial_input_with_pullup();
+ _delay_us(SLAVE_INT_RESPONSE_TIME);
// check if the slave is present
if (serial_read_pin()) {
// slave failed to pull the line low, assume not present
+ serial_output();
+ serial_high();
sei();
return 1;
}
+ // master recive phase
// if the slave is present syncronize with it
- sync_recv();
uint8_t checksum_computed = 0;
// receive data from the slave
for (int i = 0; i < SERIAL_SLAVE_BUFFER_LENGTH; ++i) {
- serial_slave_buffer[i] = serial_read_byte();
sync_recv();
+ serial_slave_buffer[i] = serial_read_byte();
checksum_computed += serial_slave_buffer[i];
}
- uint8_t checksum_received = serial_read_byte();
sync_recv();
+ uint8_t checksum_received = serial_read_byte();
if (checksum_computed != checksum_received) {
+ serial_output();
+ serial_high();
sei();
return 2;
}
+ // master switch to output
+ sync_recv(); //0
+ serial_delay(); //1
+ serial_low(); //3
+ serial_output(); // 3
+ serial_delay_half1(); //4
+
+ // master send phase
uint8_t checksum = 0;
- // send data to the slave
+
for (int i = 0; i < SERIAL_MASTER_BUFFER_LENGTH; ++i) {
+ sync_send();
serial_write_byte(serial_master_buffer[i]);
- sync_recv();
checksum += serial_master_buffer[i];
}
+ sync_send();
serial_write_byte(checksum);
- sync_recv();
// always, release the line when not in use
- serial_output();
- serial_high();
+ sync_send();
sei();
return 0;
projects / qmk_firmware.git / commitdiff