mirror of
https://github.com/betaflight/betaflight.git
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422 lines
13 KiB
C
422 lines
13 KiB
C
/*
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* This file is part of Cleanflight.
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*
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* Cleanflight is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Cleanflight is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Cleanflight. If not, see <http://www.gnu.org/licenses/>.
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*
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* FlySky iBus telemetry implementation by CraigJPerry.
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* Unit tests and some additions by Unitware
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*
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* Many thanks to Dave Borthwick's iBus telemetry dongle converter for
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* PIC 12F1572 (also distributed under GPLv3) which was referenced to
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* clarify the protocol.
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*/
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#include <stdbool.h>
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#include <stdint.h>
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#include <string.h>
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#include "platform.h"
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#if defined(TELEMETRY) && defined(TELEMETRY_IBUS)
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#include "common/axis.h"
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#include "common/utils.h"
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#include "config/parameter_group.h"
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#include "config/parameter_group_ids.h"
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#include "drivers/system.h"
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#include "drivers/sensor.h"
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#include "drivers/accgyro.h"
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#include "drivers/serial.h"
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#include "fc/rc_controls.h"
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#include "io/serial.h"
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#include "sensors/sensors.h"
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#include "sensors/acceleration.h"
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#include "sensors/battery.h"
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#include "sensors/barometer.h"
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#include "scheduler/scheduler.h"
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#include "telemetry/ibus.h"
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#include "telemetry/telemetry.h"
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/*
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* iBus Telemetry is a half-duplex serial protocol. It shares 1 line for
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* both TX and RX. It runs at a fixed baud rate of 115200. Queries are sent
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* every 7ms by the iBus receiver. Multiple sensors can be daisy chained with
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* ibus but this is implemented but not tested because i don't have one of the
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* sensors to test with
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*
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* _______
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* / \ /---------\
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* | STM32 |--UART TX-->[Bi-directional @ 115200 baud]<--| IBUS RX |
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* | uC |--UART RX--x[not connected] \---------/
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* \_______/
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*
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*
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* The protocol is driven by the iBus receiver, currently either an IA6B or
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* IA10. All iBus traffic is little endian. It begins with the iBus rx
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* querying for a sensor on the iBus:
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*
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*
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* /---------\
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* | IBUS RX | > Hello sensor at address 1, are you there?
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* \---------/ [ 0x04, 0x81, 0x7A, 0xFF ]
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*
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* 0x04 - Packet Length
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* 0x81 - bits 7-4 Command (1000 = discover sensor)
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* bits 3-0 Address (0001 = address 1)
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* 0x7A, 0xFF - Checksum, 0xFFFF - (0x04 + 0x81)
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*
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*
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* Due to the daisy-chaining, this hello also serves to inform the sensor
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* of its address (position in the chain). There are 16 possible addresses
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* in iBus, however address 0 is reserved for the rx's internally measured
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* voltage leaving 0x1 to 0xF remaining.
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*
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* Having learned it's address, the sensor simply echos the message back:
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*
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*
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* /--------\
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* Yes, i'm here, hello! < | Sensor |
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* [ 0x04, 0x81, 0x7A, 0xFF ] \--------/
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*
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* 0x04, 0x81, 0x7A, 0xFF - Echo back received packet
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*
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*
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* On receipt of a response, the iBus rx next requests the sensor's type:
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*
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*
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* /---------\
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* | IBUS RX | > Sensor at address 1, what type are you?
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* \---------/ [ 0x04, 0x91, 0x6A, 0xFF ]
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*
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* 0x04 - Packet Length
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* 0x91 - bits 7-4 Command (1001 = request sensor type)
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* bits 3-0 Address (0001 = address 1)
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* 0x6A, 0xFF - Checksum, 0xFFFF - (0x04 + 0x91)
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*
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*
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* To which the sensor responds with its details:
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*
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*
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* /--------\
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* Yes, i'm here, hello! < | Sensor |
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* [ 0x06 0x91 0x00 0x02 0x66 0xFF ] \--------/
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*
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* 0x06 - Packet Length
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* 0x91 - bits 7-4 Command (1001 = request sensor type)
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* bits 3-0 Address (0001 = address 1)
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* 0x00 - Measurement type (0 = internal voltage)
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* 0x02 - Unknown, always 0x02
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* 0x66, 0xFF - Checksum, 0xFFFF - (0x06 + 0x91 + 0x00 + 0x02)
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*
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*
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* The iBus rx continues the discovery process by querying the next
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* address. Discovery stops at the first address which does not respond.
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*
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* The iBus rx then begins a continual loop, requesting measurements from
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* each sensor discovered:
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*
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*
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* /---------\
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* | IBUS RX | > Sensor at address 1, please send your measurement
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* \---------/ [ 0x04, 0xA1, 0x5A, 0xFF ]
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*
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* 0x04 - Packet Length
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* 0xA1 - bits 7-4 Command (1010 = request measurement)
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* bits 3-0 Address (0001 = address 1)
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* 0x5A, 0xFF - Checksum, 0xFFFF - (0x04 + 0xA1)
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*
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*
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* /--------\
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* I'm reading 0 volts < | Sensor |
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* [ 0x06 0xA1 0x00 0x00 0x5E 0xFF ] \--------/
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*
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* 0x06 - Packet Length
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* 0xA1 - bits 7-4 Command (1010 = request measurement)
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* bits 3-0 Address (0001 = address 1)
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* 0x00, 0x00 - The measurement
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* 0x58, 0xFF - Checksum, 0xFFFF - (0x06 + 0xA1 + 0x00 + 0x00)
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*
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*
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* Due to the limited telemetry data types possible with ibus, we
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* simply send everything which can be represented. Currently this
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* is voltage and temperature.
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*
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*/
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#define IBUS_TASK_PERIOD_US (1000)
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#define IBUS_UART_MODE (MODE_RXTX)
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#define IBUS_BAUDRATE (115200)
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#define IBUS_CYCLE_TIME_MS (8)
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#define IBUS_CHECKSUM_SIZE (2)
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#define IBUS_MIN_LEN (2 + IBUS_CHECKSUM_SIZE)
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#define IBUS_MAX_TX_LEN (6)
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#define IBUS_MAX_RX_LEN (4)
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#define IBUS_RX_BUF_LEN (IBUS_MAX_RX_LEN)
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#define IBUS_TEMPERATURE_OFFSET (400)
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typedef uint8_t ibusAddress_t;
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typedef enum {
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IBUS_COMMAND_DISCOVER_SENSOR = 0x80,
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IBUS_COMMAND_SENSOR_TYPE = 0x90,
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IBUS_COMMAND_MEASUREMENT = 0xA0
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} ibusCommand_e;
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typedef enum {
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IBUS_SENSOR_TYPE_TEMPERATURE = 0x01,
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IBUS_SENSOR_TYPE_RPM = 0x02,
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IBUS_SENSOR_TYPE_EXTERNAL_VOLTAGE = 0x03
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} ibusSensorType_e;
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/* Address lookup relative to the sensor base address which is the lowest address seen by the FC
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The actual lowest value is likely to change when sensors are daisy chained */
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static const uint8_t sensorAddressTypeLookup[] = {
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IBUS_SENSOR_TYPE_EXTERNAL_VOLTAGE,
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IBUS_SENSOR_TYPE_TEMPERATURE,
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IBUS_SENSOR_TYPE_RPM
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};
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static serialPort_t *ibusSerialPort = NULL;
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static serialPortConfig_t *ibusSerialPortConfig;
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/* The sent bytes will be echoed back since Tx and Rx are wired together, this counter
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* will keep track of how many rx chars that shall be discarded */
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static uint8_t outboundBytesToIgnoreOnRxCount = 0;
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static bool ibusTelemetryEnabled = false;
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static portSharing_e ibusPortSharing;
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#define INVALID_IBUS_ADDRESS 0
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static ibusAddress_t ibusBaseAddress = INVALID_IBUS_ADDRESS;
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static uint8_t ibusReceiveBuffer[IBUS_RX_BUF_LEN] = { 0x0 };
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static uint16_t calculateChecksum(const uint8_t *ibusPacket, size_t packetLength)
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{
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uint16_t checksum = 0xFFFF;
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for (size_t i = 0; i < packetLength - IBUS_CHECKSUM_SIZE; i++) {
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checksum -= ibusPacket[i];
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}
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return checksum;
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}
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static bool isChecksumOk(const uint8_t *ibusPacket)
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{
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uint16_t calculatedChecksum = calculateChecksum(ibusReceiveBuffer, IBUS_RX_BUF_LEN);
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// Note that there's a byte order swap to little endian here
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return (calculatedChecksum >> 8) == ibusPacket[IBUS_RX_BUF_LEN - 1]
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&& (calculatedChecksum & 0xFF) == ibusPacket[IBUS_RX_BUF_LEN - 2];
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}
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static void transmitIbusPacket(uint8_t *ibusPacket, size_t payloadLength)
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{
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uint16_t checksum = calculateChecksum(ibusPacket, payloadLength + IBUS_CHECKSUM_SIZE);
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for (size_t i = 0; i < payloadLength; i++) {
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serialWrite(ibusSerialPort, ibusPacket[i]);
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}
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serialWrite(ibusSerialPort, checksum & 0xFF);
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serialWrite(ibusSerialPort, checksum >> 8);
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outboundBytesToIgnoreOnRxCount += payloadLength + IBUS_CHECKSUM_SIZE;
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}
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static void sendIbusDiscoverSensorReply(ibusAddress_t address)
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{
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uint8_t sendBuffer[] = { 0x04, IBUS_COMMAND_DISCOVER_SENSOR | address};
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transmitIbusPacket(sendBuffer, sizeof(sendBuffer));
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}
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static void sendIbusSensorType(ibusAddress_t address)
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{
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uint8_t sendBuffer[] = {0x06,
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IBUS_COMMAND_SENSOR_TYPE | address,
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sensorAddressTypeLookup[address - ibusBaseAddress],
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0x02
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};
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transmitIbusPacket(sendBuffer, sizeof(sendBuffer));
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}
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static void sendIbusMeasurement(ibusAddress_t address, uint16_t measurement)
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{
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uint8_t sendBuffer[] = { 0x06, IBUS_COMMAND_MEASUREMENT | address, measurement & 0xFF, measurement >> 8};
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transmitIbusPacket(sendBuffer, sizeof(sendBuffer));
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}
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static bool isCommand(ibusCommand_e expected, const uint8_t *ibusPacket)
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{
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return (ibusPacket[1] & 0xF0) == expected;
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}
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static ibusAddress_t getAddress(const uint8_t *ibusPacket)
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{
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return (ibusPacket[1] & 0x0F);
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}
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static void dispatchMeasurementReply(ibusAddress_t address)
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{
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int value;
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switch (sensorAddressTypeLookup[address - ibusBaseAddress]) {
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case IBUS_SENSOR_TYPE_EXTERNAL_VOLTAGE:
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value = getVbat() * 10;
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if (telemetryConfig()->report_cell_voltage) {
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value /= batteryCellCount;
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}
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sendIbusMeasurement(address, value);
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break;
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case IBUS_SENSOR_TYPE_TEMPERATURE:
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#ifdef BARO
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value = (baro.baroTemperature + 5) / 10; // +5 to make integer division rounding correct
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#else
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value = gyroGetTemperature() * 10;
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#endif
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sendIbusMeasurement(address, value + IBUS_TEMPERATURE_OFFSET);
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break;
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case IBUS_SENSOR_TYPE_RPM:
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sendIbusMeasurement(address, (uint16_t) rcCommand[THROTTLE]);
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break;
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}
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}
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static void autodetectFirstReceivedAddressAsBaseAddress(ibusAddress_t returnAddress)
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{
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if ((INVALID_IBUS_ADDRESS == ibusBaseAddress) &&
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(INVALID_IBUS_ADDRESS != returnAddress)) {
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ibusBaseAddress = returnAddress;
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}
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}
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static bool theAddressIsWithinOurRange(ibusAddress_t returnAddress)
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{
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return (returnAddress >= ibusBaseAddress) &&
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(ibusAddress_t)(returnAddress - ibusBaseAddress) < ARRAYLEN(sensorAddressTypeLookup);
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}
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static void respondToIbusRequest(uint8_t ibusPacket[static IBUS_RX_BUF_LEN])
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{
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ibusAddress_t returnAddress = getAddress(ibusPacket);
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autodetectFirstReceivedAddressAsBaseAddress(returnAddress);
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if (theAddressIsWithinOurRange(returnAddress)) {
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if (isCommand(IBUS_COMMAND_DISCOVER_SENSOR, ibusPacket)) {
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sendIbusDiscoverSensorReply(returnAddress);
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} else if (isCommand(IBUS_COMMAND_SENSOR_TYPE, ibusPacket)) {
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sendIbusSensorType(returnAddress);
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} else if (isCommand(IBUS_COMMAND_MEASUREMENT, ibusPacket)) {
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dispatchMeasurementReply(returnAddress);
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}
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}
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}
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static void pushOntoTail(uint8_t buffer[IBUS_MIN_LEN], size_t bufferLength, uint8_t value)
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{
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memmove(buffer, buffer + 1, bufferLength - 1);
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ibusReceiveBuffer[bufferLength - 1] = value;
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}
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void initIbusTelemetry(void)
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{
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ibusSerialPortConfig = findSerialPortConfig(FUNCTION_TELEMETRY_IBUS);
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ibusPortSharing = determinePortSharing(ibusSerialPortConfig, FUNCTION_TELEMETRY_IBUS);
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ibusBaseAddress = INVALID_IBUS_ADDRESS;
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}
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void handleIbusTelemetry(void)
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{
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if (!ibusTelemetryEnabled) {
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return;
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}
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while (serialRxBytesWaiting(ibusSerialPort) > 0) {
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uint8_t c = serialRead(ibusSerialPort);
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if (outboundBytesToIgnoreOnRxCount) {
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outboundBytesToIgnoreOnRxCount--;
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continue;
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}
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pushOntoTail(ibusReceiveBuffer, IBUS_RX_BUF_LEN, c);
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if (isChecksumOk(ibusReceiveBuffer)) {
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respondToIbusRequest(ibusReceiveBuffer);
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}
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}
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}
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bool checkIbusTelemetryState(void)
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{
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bool newTelemetryEnabledValue = telemetryDetermineEnabledState(ibusPortSharing);
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if (newTelemetryEnabledValue == ibusTelemetryEnabled) {
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return false;
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}
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if (newTelemetryEnabledValue) {
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rescheduleTask(TASK_TELEMETRY, IBUS_TASK_PERIOD_US);
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configureIbusTelemetryPort();
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} else {
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freeIbusTelemetryPort();
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}
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return true;
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}
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void configureIbusTelemetryPort(void)
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{
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portOptions_t portOptions;
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if (!ibusSerialPortConfig) {
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return;
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}
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portOptions = SERIAL_BIDIR;
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ibusSerialPort = openSerialPort(ibusSerialPortConfig->identifier, FUNCTION_TELEMETRY_IBUS, NULL, IBUS_BAUDRATE,
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IBUS_UART_MODE, portOptions);
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if (!ibusSerialPort) {
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return;
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}
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ibusTelemetryEnabled = true;
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outboundBytesToIgnoreOnRxCount = 0;
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}
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void freeIbusTelemetryPort(void)
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{
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closeSerialPort(ibusSerialPort);
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ibusSerialPort = NULL;
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ibusTelemetryEnabled = false;
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}
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#endif
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