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qmk_firmware/platforms/chibios/drivers/serial.c

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/*
* WARNING: be careful changing this code, it is very timing dependent
*/
#include "quantum.h"
#include "serial.h"
#include "wait.h"
#include <hal.h>
// TODO: resolve/remove build warnings
#if defined(RGBLIGHT_ENABLE) && defined(RGBLED_SPLIT) && defined(PROTOCOL_CHIBIOS) && defined(WS2812_DRIVER_BITBANG)
# warning "RGBLED_SPLIT not supported with bitbang WS2812 driver"
#endif
// default wait implementation cannot be called within interrupt
// this method seems to be more accurate than GPT timers
#if PORT_SUPPORTS_RT == FALSE
# error "chSysPolledDelayX method not supported on this platform"
#else
# undef wait_us
# define wait_us(x) chSysPolledDelayX(US2RTC(CPU_CLOCK, x))
#endif
#ifndef SELECT_SOFT_SERIAL_SPEED
# define SELECT_SOFT_SERIAL_SPEED 1
// TODO: correct speeds...
// 0: about 189kbps (Experimental only)
// 1: about 137kbps (default)
// 2: about 75kbps
// 3: about 39kbps
// 4: about 26kbps
// 5: about 20kbps
#endif
// Serial pulse period in microseconds. At the moment, going lower than 12 causes communication failure
#if SELECT_SOFT_SERIAL_SPEED == 0
# define SERIAL_DELAY 12
#elif SELECT_SOFT_SERIAL_SPEED == 1
# define SERIAL_DELAY 16
#elif SELECT_SOFT_SERIAL_SPEED == 2
# define SERIAL_DELAY 24
#elif SELECT_SOFT_SERIAL_SPEED == 3
# define SERIAL_DELAY 32
#elif SELECT_SOFT_SERIAL_SPEED == 4
# define SERIAL_DELAY 48
#elif SELECT_SOFT_SERIAL_SPEED == 5
# define SERIAL_DELAY 64
#else
# error invalid SELECT_SOFT_SERIAL_SPEED value
#endif
inline static void serial_delay(void) {
wait_us(SERIAL_DELAY);
}
inline static void serial_delay_half(void) {
wait_us(SERIAL_DELAY / 2);
}
inline static void serial_delay_blip(void) {
wait_us(1);
}
inline static void serial_output(void) {
setPinOutput(SOFT_SERIAL_PIN);
}
inline static void serial_input(void) {
setPinInputHigh(SOFT_SERIAL_PIN);
}
inline static bool serial_read_pin(void) {
return !!readPin(SOFT_SERIAL_PIN);
}
inline static void serial_low(void) {
writePinLow(SOFT_SERIAL_PIN);
}
inline static void serial_high(void) {
writePinHigh(SOFT_SERIAL_PIN);
}
void interrupt_handler(void *arg);
// Use thread + palWaitLineTimeout instead of palSetLineCallback
// - Methods like setPinOutput and palEnableLineEvent/palDisableLineEvent
// cause the interrupt to lock up, which would limit to only receiving data...
static THD_WORKING_AREA(waThread1, 128);
static THD_FUNCTION(Thread1, arg) {
(void)arg;
chRegSetThreadName("blinker");
while (true) {
palWaitLineTimeout(SOFT_SERIAL_PIN, TIME_INFINITE);
interrupt_handler(NULL);
}
}
void soft_serial_initiator_init(void) {
serial_output();
serial_high();
}
void soft_serial_target_init(void) {
serial_input();
palEnablePadEvent(PAL_PORT(SOFT_SERIAL_PIN), PAL_PAD(SOFT_SERIAL_PIN), PAL_EVENT_MODE_FALLING_EDGE);
chThdCreateStatic(waThread1, sizeof(waThread1), HIGHPRIO, Thread1, NULL);
}
// Used by the master to synchronize timing with the slave.
static void __attribute__((noinline)) 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 __attribute__((noinline)) sync_send(void) {
serial_output();
serial_low();
serial_delay();
serial_high();
}
// Reads a byte from the serial line
static uint8_t __attribute__((noinline)) 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();
}
return byte;
}
// Sends a byte with MSB ordering
static void __attribute__((noinline)) 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
void interrupt_handler(void *arg) {
chSysLockFromISR();
sync_send();
// read mid pulses
serial_delay_blip();
uint8_t checksum_computed = 0;
int sstd_index = 0;
sstd_index = serial_read_byte();
sync_send();
split_transaction_desc_t *trans = &split_transaction_table[sstd_index];
for (int i = 0; i < trans->initiator2target_buffer_size; ++i) {
split_trans_initiator2target_buffer(trans)[i] = serial_read_byte();
sync_send();
checksum_computed += split_trans_initiator2target_buffer(trans)[i];
}
checksum_computed ^= 7;
serial_read_byte();
sync_send();
// wait for the sync to finish sending
serial_delay();
// Allow any slave processing to occur
if (trans->slave_callback) {
trans->slave_callback(trans->initiator2target_buffer_size, split_trans_initiator2target_buffer(trans), trans->target2initiator_buffer_size, split_trans_target2initiator_buffer(trans));
}
uint8_t checksum = 0;
for (int i = 0; i < trans->target2initiator_buffer_size; ++i) {
serial_write_byte(split_trans_target2initiator_buffer(trans)[i]);
sync_send();
serial_delay_half();
checksum += split_trans_target2initiator_buffer(trans)[i];
}
serial_write_byte(checksum ^ 7);
sync_send();
// wait for the sync to finish sending
serial_delay();
// end transaction
serial_input();
// TODO: remove extra delay between transactions
serial_delay();
chSysUnlockFromISR();
}
/////////
// start transaction by initiator
//
// bool soft_serial_transaction(int sstd_index)
//
// this code is very time dependent, so we need to disable interrupts
bool soft_serial_transaction(int sstd_index) {
if (sstd_index > NUM_TOTAL_TRANSACTIONS) return false;
split_transaction_desc_t *trans = &split_transaction_table[sstd_index];
// TODO: remove extra delay between transactions
serial_delay();
// this code is very time dependent, so we need to disable interrupts
chSysLock();
// signal to the slave that we want to start a transaction
serial_output();
serial_low();
serial_delay_blip();
// wait for the slaves response
serial_input();
serial_high();
serial_delay();
// check if the slave is present
if (serial_read_pin()) {
// slave failed to pull the line low, assume not present
dprintf("serial::NO_RESPONSE\n");
chSysUnlock();
return false;
}
// if the slave is present syncronize with it
uint8_t checksum = 0;
// send data to the slave
serial_write_byte(sstd_index); // first chunk is transaction id
sync_recv();
for (int i = 0; i < trans->initiator2target_buffer_size; ++i) {
serial_write_byte(split_trans_initiator2target_buffer(trans)[i]);
sync_recv();
checksum += split_trans_initiator2target_buffer(trans)[i];
}
serial_write_byte(checksum ^ 7);
sync_recv();
serial_delay();
serial_delay(); // read mid pulses
// receive data from the slave
uint8_t checksum_computed = 0;
for (int i = 0; i < trans->target2initiator_buffer_size; ++i) {
split_trans_target2initiator_buffer(trans)[i] = serial_read_byte();
sync_recv();
checksum_computed += split_trans_target2initiator_buffer(trans)[i];
}
checksum_computed ^= 7;
uint8_t checksum_received = serial_read_byte();
sync_recv();
serial_delay();
if ((checksum_computed) != (checksum_received)) {
dprintf("serial::FAIL[%u,%u,%u]\n", checksum_computed, checksum_received, sstd_index);
serial_output();
serial_high();
chSysUnlock();
return false;
}
// always, release the line when not in use
serial_high();
serial_output();
chSysUnlock();
return true;
}