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doc:crazyflie:syslink:index [2015-02-25 14:49]
arnaud [Radio RSSI] 		doc:crazyflie:syslink:index [2020-05-12 14:14] (current)
kimberly
Line 1: Line 1:
 +<WRAP center round important 60%>
 +This page has deprecated and moved to the new documentation framework of the main Bitcraze website. Please go to [[https://www.bitcraze.io/documentation/system/]]
 +</WRAP>
  
 +
 +====== Syslink protocol ======
 +
 +Syslink is the protocol used between the STM32 and NRF51 in Crazyflie 2.0. It handles low level communication on the serial port.
 +
 +===== Physical format =====
 +
 +In Crazyflie 2.0 syslink is transmitted on serial port at 1MBaud. It is a packet-based protocol.
 +
 +<code>
 +  +-----------+------+-----+=============+-----+-----+
 +  |   START   | TYPE | LEN | DATA        |   CKSUM   |
 +  +-----------+------+-----+=============+-----+-----+
 +</code>
 +
 +  * **START** is 2 bytes constant, 0xBC 0xCF.
 +  * **TYPE** defines the type of packet
 +  * **LENGTH** and type are uint8_t, defines the data length.
 +  * **CKSUM** is 2 bytes Fletcher 8 bit checksum. See [[https://tools.ietf.org/html/rfc1146|rfc1146]]. calculated with TYPE, LEN and DATA.
 +
 +**Note**: Unless otherwise specified, all numbers are encoded in low-endian form.
 +
 +===== Packet types =====
 +
 +Packet types is defined in the syslink.h file (in the [[https://github.com/bitcraze/crazyflie-firmware/blob/crazyflie2/hal/interface/syslink.h|stm32]] and [[https://github.com/bitcraze/crazyflie2-nrf-firmware/blob/master/interface/syslink.h|nrf51]] firmware).
 +
 +Packets are organized in groups to ease routing in firmwares:
 +^ Group  ^ Name ^ Description ^
 +| 0x00   | [[#radio_packets|RADIO]] | Radio related packets. For data and configuration |
 +| 0x10   | [[#power_management_packets|PM]]   | Power management |
 +| 0x20   | [[#one_wire_packets|OW]]   | One wire memory access |
 +
 +A packet type has its group in the high nibble and the type in the low nibble. In the rest of the page packet type are written with group.
 +
 +===== Radio packets =====
 +
 +==== RADIO_RAW ====
 +
 +  * **Type**: 0x00
 +  * **Data format**: Raw radio packet as sent in the air
 +
 +This packet carries the raw radio packet. The NRF51 acts as a radio bridge. Because the NRF51 does not have much memory and the STM32 is capable of bursting a lot of data a flow control rules has been made: The STM32 is allowed to send a RADIO_RAW packet only when one RADIO_RAW packet has been received.
 +
 +The NRF51 is regularly sending CRTP NULL packet or empty packets to the STM32 to get the communication working both ways.
 +
 +<WRAP round info >
 +//**Note**//
 +So far RADIO_RAW is the only syslink packet that has flow control constrain, all other packets can be sent full duplex at any moment.
 +</WRAP>
 +
 +==== RADIO_CHANNEL ====
 +  * **Type**: 0x01
 +  * **Data format**: One uint8_t indicating the radio channel
 +
 +This packet is used only in ESB mode.
 +
 +Packet sent to the NRF51 to set the radio channel to use. The NRF51 then send back the same packet to confirm that the setting has been done.
 +
 +NRF51 radio channel are spaced by 1MHz from 2400MHz to 2525MHz.
 +
 +==== RADIO_DATARATE ====
 +  * **Type**: 0x02
 +  * **Data format**: One uint8_t indicating the radio datarate.
 +
 +This packet is used only in ESB mode.
 +
 +Packet sent to the NRF51 to set the radio datarate to use. The NRF51 then send back the same packet to confirm that the setting has been done.
 +
 +Possible datarate:
 +^ Value ^ Datarate ^
 +| 0     | 250Kbps  |
 +| 1     | 1Mbps    |
 +| 2     | 2Mbps    |
 +
 +==== RADIO_CONTWAVE ====
 +  * **Type**: 0x03
 +  * **Data format**: One uint8_t at 0 for disable, >0 for enable.
 +
 +Allows to put the nRF51 in continuous wave mode. If enabled the nRF51 will disable Bluetooth advertising and set its radio to emit a continuous sinus wave at the currently set channel frequency.
 +
 +<WRAP center round important>
 +//**Warning**//
 +Continuous wave is a test mode used, among other thing, during manufacturing test. It will affect other wireless communication like Wifi and should be used with care in a test environment
 +</WRAP>
 +
 +==== RADIO_RSSI ====
 +  * **Type**: 0x03
 +  * **Data format**: One uint8_t indicating the last received pachet RSSI
 +
 +This packet is meaningful only in ESB mode.
 +
 +Packet sent 100 times per seconds to the STM32. Contains the power value of the latest received packet. The value is the same as reported by the NRF51: between 40 and 100 which means measurement of -40dBm to -100dBm.
 +
 +===== Power management packets =====
 +
 +==== SYSLINK_PM_ONOFF_SWITCHOFF ====
 +  * **Type**: 0x11
 +  * **Format**: No data
 +
 +When sent by the STM32 to the NRF51, the NRF51 switch OFF the system and goes in deep sleep.
 +
 +==== SYSLINK_PM_BATTERY_STATE ====
 +<WRAP group>
 +<WRAP column>
 +  * **Type**: 0x13
 +  * **Format**:
 +</WRAP>
 +
 +<WRAP column>
 +<ditaa noedgesep>
 + +-------+------+------+
 + | Flags | VBAT | ISET |
 + +-------+------+------+
 +     1      4       4
 +</ditaa>
 +</WRAP>
 +<WRAP column>
 +  * **Flags**: Bit0: Charging. Bit1: USB Powered.
 +  * **VBAT**: IEEE single float. Battery voltage.
 +  * **ISET**: IEEE single float. Charge current in milli-Ampers.
 +</WRAP>
 +
 +</WRAP>
 +
 +
 +
 +
 +The SYSLINK_PM_BATTERY_STATE packet is sent 100 times per seconds to the STM32.
 +===== One Wire packets =====

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