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frsky_telemetry: add S.Port single-wire support 

If S.Port is connected via external inverter or an uninverted signal is
used, the UART needs to be put into half-duplex mode.

This can be used to get uninverted S.Port:
https://oscarliang.com/uninverted-sbus-smart-port-frsky-receivers/

It is not needed for the Pixracer FrSky port.
This commit is contained in:
Beat Küng 2018-07-07 09:07:20 +02:00 committed by Lorenz Meier
parent 1feccfcc81
commit f3292c7741
1 changed files with 51 additions and 26 deletions
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77
src/drivers/telemetry/frsky_telemetry/frsky_telemetry.cpp
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@ -51,6 +51,7 @@
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <poll.h>
#include <fcntl.h>
@ -69,12 +70,13 @@
#include "frsky_data.h"
#include "common.h"
using namespace time_literals;
/* thread state */
static volatile bool thread_should_exit = false;
static volatile bool thread_running = false;
static int frsky_task;
typedef enum { SCANNING, SPORT, DTYPE } frsky_state_t;
typedef enum { SCANNING, SPORT, SPORT_SINGLE_WIRE, DTYPE } frsky_state_t;
static frsky_state_t frsky_state = SCANNING;
static unsigned long int sentPackets = 0;
@ -198,6 +200,13 @@ static int set_uart_speed(int uart, struct termios *uart_config, speed_t speed)
return uart;
}
static void set_uart_single_wire(int uart, bool single_wire)
{
if (ioctl(uart, TIOCSSINGLEWIRE, single_wire ? SER_SINGLEWIRE_ENABLED : 0) < 0) {
PX4_WARN("setting TIOCSSINGLEWIRE failed");
}
}
/**
* Print command usage information
*/
@ -262,19 +271,19 @@ static int frsky_telemetry_thread_main(int argc, char *argv[])
/* 2 byte polling frames indicate SmartPort telemetry
* 11 byte packets indicate D type telemetry
*/
int status = poll(fds, sizeof(fds) / sizeof(fds[0]), 3000);
int status = poll(fds, sizeof(fds) / sizeof(fds[0]), 1000);
if (status > 0) {
/* traffic on the port, D type is 11 bytes per frame, SmartPort is only 2
* Wait long enough for 11 bytes at 9600 baud
*/
usleep(12000);
usleep(50_ms);
int nbytes = read(uart, &sbuf[0], sizeof(sbuf));
PX4_DEBUG("frsky input: %d bytes: %x %x, speed: %d", nbytes, sbuf[0], sbuf[1], baudRate);
// look for valid header byte
if (nbytes > 10) {
if (baudRate == DTYPE) {
if (baudRate == DTYPE) {
if (nbytes > 10) {
// see if we got a valid D-type hostframe
struct adc_linkquality host_frame;
@ -282,8 +291,10 @@ static int frsky_telemetry_thread_main(int argc, char *argv[])
frsky_state = baudRate;
break;
}
}
} else {
} else {
if (nbytes > 1) {
// check for alternating S.port start bytes
int index = 0;
@ -305,29 +316,37 @@ static int frsky_telemetry_thread_main(int argc, char *argv[])
}
}
// alternate between S.port and D-type baud rates
if (baudRate == SPORT) {
PX4_DEBUG("setting baud rate to %d", 9600);
set_uart_speed(uart, &uart_config, B9600);
baudRate = DTYPE;
} else {
PX4_DEBUG("setting baud rate to %d", 57600);
set_uart_speed(uart, &uart_config, B57600);
baudRate = SPORT;
}
// wait a second
usleep(1000000);
// flush buffer
read(uart, &sbuf[0], sizeof(sbuf));
}
// alternate between S.port and D-type baud rates
if (baudRate == SPORT) {
PX4_DEBUG("setting baud rate to %d (single wire)", 57600);
set_uart_speed(uart, &uart_config, B57600);
// switch to single-wire (half-duplex) mode, because S.Port uses only a single wire
set_uart_single_wire(uart, true);
baudRate = SPORT_SINGLE_WIRE;
} else if (baudRate == SPORT_SINGLE_WIRE) {
PX4_DEBUG("setting baud rate to %d", 9600);
set_uart_speed(uart, &uart_config, B9600);
set_uart_single_wire(uart, false);
baudRate = DTYPE;
} else {
PX4_DEBUG("setting baud rate to %d", 57600);
set_uart_speed(uart, &uart_config, B57600);
// in case S.Port is connected via external inverter (e.g. via Sipex 3232EE), we need to use duplex mode
set_uart_single_wire(uart, false);
baudRate = SPORT;
}
usleep(100_ms);
// flush buffer
read(uart, &sbuf[0], sizeof(sbuf));
}
if (frsky_state == SPORT) {
if (frsky_state == SPORT || frsky_state == SPORT_SINGLE_WIRE) {
/* Subscribe to topics */
if (!sPort_init()) {
PX4_ERR("could not allocate memory");
@ -725,6 +744,12 @@ int frsky_telemetry_main(int argc, char *argv[])
PX4_INFO("packets sent: %d", sentPackets);
break;
case SPORT_SINGLE_WIRE:
PX4_INFO("running: SPORT (single wire)");
PX4_INFO("port: %s", device_name);
PX4_INFO("packets sent: %d", sentPackets);
break;
case DTYPE:
PX4_INFO("running: DTYPE");
PX4_INFO("port: %s", device_name);