diff options
Diffstat (limited to 'keyboards/ergo42/serial.c')
-rw-r--r-- | keyboards/ergo42/serial.c | 228 |
1 files changed, 0 insertions, 228 deletions
diff --git a/keyboards/ergo42/serial.c b/keyboards/ergo42/serial.c deleted file mode 100644 index 74bcbb6bf6..0000000000 --- a/keyboards/ergo42/serial.c +++ /dev/null @@ -1,228 +0,0 @@ -/* - * 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 <stdbool.h> -#include "serial.h" - -#ifndef USE_I2C - -// Serial pulse period in microseconds. Its probably a bad idea to lower this -// value. -#define SERIAL_DELAY 24 - -uint8_t volatile serial_slave_buffer[SERIAL_SLAVE_BUFFER_LENGTH] = {0}; -uint8_t volatile serial_master_buffer[SERIAL_MASTER_BUFFER_LENGTH] = {0}; - -#define SLAVE_DATA_CORRUPT (1<<0) -volatile uint8_t status = 0; - -inline static -void serial_delay(void) { - _delay_us(SERIAL_DELAY); -} - -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) { - 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) { - SERIAL_PIN_PORT &= ~SERIAL_PIN_MASK; -} - -inline static -void serial_high(void) { - SERIAL_PIN_PORT |= SERIAL_PIN_MASK; -} - -void serial_master_init(void) { - serial_output(); - serial_high(); -} - -void serial_slave_init(void) { - serial_input(); - - // Enable INT0 - EIMSK |= _BV(INT0); - // Trigger on falling edge of INT0 - EICRA &= ~(_BV(ISC00) | _BV(ISC01)); -} - -// Used by the master to synchronize timing with the slave. -static -void sync_recv(void) { - serial_input(); - // 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(); -} - -// Used by the slave to send a synchronization signal to the master. -static -void sync_send(void) { - serial_output(); - - serial_low(); - serial_delay(); - - serial_high(); -} - -// Reads a byte from the serial line -static -uint8_t serial_read_byte(void) { - uint8_t byte = 0; - serial_input(); - for ( uint8_t i = 0; i < 8; ++i) { - byte = (byte << 1) | serial_read_pin(); - serial_delay(); - _delay_us(1); - } - - 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)) { - serial_high(); - } else { - serial_low(); - } - serial_delay(); - } -} - -// interrupt handle to be used by the slave device -ISR(SERIAL_PIN_INTERRUPT) { - sync_send(); - - uint8_t checksum = 0; - for (int i = 0; i < SERIAL_SLAVE_BUFFER_LENGTH; ++i) { - serial_write_byte(serial_slave_buffer[i]); - sync_send(); - checksum += serial_slave_buffer[i]; - } - serial_write_byte(checksum); - sync_send(); - - // wait for the sync to finish sending - serial_delay(); - - // read the middle of pulses - _delay_us(SERIAL_DELAY/2); - - uint8_t checksum_computed = 0; - for (int i = 0; i < SERIAL_MASTER_BUFFER_LENGTH; ++i) { - serial_master_buffer[i] = serial_read_byte(); - sync_send(); - checksum_computed += serial_master_buffer[i]; - } - 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; - } -} - -inline -bool serial_slave_DATA_CORRUPT(void) { - return status & SLAVE_DATA_CORRUPT; -} - -// Copies the serial_slave_buffer to the master and sends the -// serial_master_buffer to the slave. -// -// Returns: -// 0 => no error -// 1 => slave did not respond -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); - - // wait for the slaves response - serial_input(); - serial_high(); - _delay_us(SERIAL_DELAY); - - // check if the slave is present - if (serial_read_pin()) { - // slave failed to pull the line low, assume not present - sei(); - return 1; - } - - // 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(); - checksum_computed += serial_slave_buffer[i]; - } - uint8_t checksum_received = serial_read_byte(); - sync_recv(); - - if (checksum_computed != checksum_received) { - sei(); - return 1; - } - - uint8_t checksum = 0; - // send data to the slave - for (int i = 0; i < SERIAL_MASTER_BUFFER_LENGTH; ++i) { - serial_write_byte(serial_master_buffer[i]); - sync_recv(); - checksum += serial_master_buffer[i]; - } - serial_write_byte(checksum); - sync_recv(); - - // always, release the line when not in use - serial_output(); - serial_high(); - - sei(); - return 0; -} - -#endif |