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Implement these functions in your application
The following functions are only for builds that support software flow control and that are compiled with EMBER_APPLICATION_SUPPORTS_SOFTWARE_FLOW_CONTROL
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void
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emberXOnHandler
(void)
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Tell the application that we received an XON.
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void
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emberXOffHandler
(void)
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Tell the application that we received an XOFF.
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* ASHv3 Header (4 bytes)
* 0 1 2 3
+-+-+-+-+-+-+-+-+|+-+-+-+-+-+-+-+-+|+-+-+-+-+-+-+-+-+|+-+-+-+-+-+-+-+-+
+ ASH_FLAG | HEADER ESCAPE | CONTROL BYTE | PAYLOAD LENGTH +
+-+-+-+-+-+-+-+-+|+-+-+-+-+-+-+-+-+|+-+-+-+-+-+-+-+-+|+-+-+-+-+-+-+-+-+
+
+ ASH_FLAG is defined below
+
+ Header Escape bytes contains escape data for the control byte and the payload
+ length byte, and is encoded as:
+
+-+-+-+-+-+-+-+-+
+A B +
+-+-+-+-+-+-+-+-+
+
+ where A and B are booleans representing:
+ A = is the control byte escaped? (1 << 7)
+ B = is the payload length byte escaped? (1 << 6)
+
+ The control byte has the syntax:
+
+-+-+-+-+-+-+-+-+
+ T + OFC + AFC +
+-+-+-+-+-+-+-+-+
+
+ where:
+
+ T = type (see AshMessageType below)
+ OFC = outgoing frame counter
+ AFC = ack/nack frame counter
+
+ Payload length is in the range: [0, MAX_ASH_PAYLOAD_SIZE] (defined below)
+
+ The CRC is 3 bytes and contains 2 bytes of data. It is stored in such a way
+ that each of its bytes never needs escaping.
+
+ The escape bytes are:
+
+ ASH_FLAG 0b01111110
+ ASH_ESC 0b01111101
+ ASH_XON 0b00010001
+ ASH_XOFF 0b00010011
+ ASH_COBRA_FORCE_BOOT 0b11111000
+ ^ They all have this bit set
+
+ The CRC is expanded in the following way:
+
+-+-+-+-+-+-+-+-+|+-+-+-+-+-+-+-+-+
+ High CRC + Low CRC +
+-+-+-+-+-+-+-+-+|+-+-+-+-+-+-+-+-+
+ F E D C B A 9 8 7 6 5 4 3 2 1 0
+ ^ ^-------------+
+-----------------------------+ |
+-+-+-+-+-+-+-+-+|+-+-+-+-+-+-+-+-+|+-+-+-+-+-+-+-+-+
+ New High CRC | New Low CRC | Bits +
+-+-+-+-+-+-+-+-+|+-+-+-+-+-+-+-+-+|+-+-+-+-+-+-+-+-+
+ 7 6 5 4 3 2 1 0
+
+ -----------------------------------------------------------------------------
+ PROTOCOL
+
* Design
*
* The upward interface sends and receives a stream of bytes. The upper layer
* writes and reads data in blocks, but the block boundaries are not preserved
* over the wire. The UART framing is independent of the upward interface; the
* data is treated as a stream.
*
* The protocol is organized around using a single DMA operation to send a
* frame. The maximum size is of a DMA buffer is 100 bytes. Getting good
* throughput requires allowing two frames in flight; having more does not help.
* The UART is responsible for ACKing and retrying frames over the wire. Each
* frame contains a sequence number, the sequence number of the most recently
* received frame, and a flag indicating whether or not corrupt data was
* received after that frame.
*
* An OFC value of 0 is never used because 0 is the AFC's default/uninitialized
* value.
*
* Resets
*
* To reset the UART link a device sends a RESET frame and the peer responds
* with a RESET_ACK frame. RESET and RESET_ACK frames have a single data byte that
* gives the type of reset. For a RESET packet, the OFC is set to 1 and the AFC
* is set to 0. For a RESET_ACK packet with no payload, the OFC is 1 and the AFC
* is 1. For an RESET_ACK with non-empty payload, the OFC is 2 and the AFC is 1.
*
* ACKs, NACKs and retransmission
*
* The driver retains transmitted frames until a matching ACK is received.
* Frames are retransmitted if a NACK is received or, in case an ACK is lost,
* if a resend timer expires.
*
* ACK, NACK, and RESET_ACK frames can carry data. The ACK/NACK counter has the
* frame counter from the last correctly received frame. A NACK frame is sent if
* corrupt data or a corrupt frame is received. An ACK frame is sent whenever a
* data-containing frame is received correctly. If an ACK/NACK has no payload,
* its OFC is ignored and no ACK is sent in response. Note that we record an
* RESET_ACK's OFC whether or not its payload is populated. An ACK/NACK/RESET_ACK with
* empty payload must not have an incremented OFC.
*
* After sending a RESET frame all incoming ACK and NACK frames are ignored
* until an RESET_ACK is received. Additional incoming RESET frames are answered
* with a matching RESET_ACK.
*
* Waking
*
* When using the UART to wake up the other device, the byte 0xFF (ASH_WAKEUP)
* can be sent in betweem frames. This only applies between frames, so 0xFF does
* not need to be escaped within a frame. Any number of wake bytes can be sent
* between the ASH_FLAG at the end of one frame and an ASH_FLAG at the beginning
* of the next frame.
*
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void emberXOffHandler
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(
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void
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)
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void emberXOnHandler
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(
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void
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)
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uint8_t AshTxState::ackNackFrameCounter
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uint16_t AshRxState::computedCrc
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uint8_t AshRxState::controlByte
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uint8_t AshTxDmaBuffer::data[
MAX_ASH_PACKET_SIZE
]
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uint8_t AshRxState::escapedPayloadIndex
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bool AshRxState::escapeNextByte
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uint8_t* AshTxDmaBuffer::finger
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AshRxFrameState
AshRxState::frameState
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uint8_t AshRxState::headerEscapeByte
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uint8_t AshRxState::highCrcByte
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uint8_t AshRxState::inBetweenCrcByte
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bool AshTxDmaBuffer::isCorrupt
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uint8_t AshTxState::outgoingFrameCounter
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uint8_t AshRxState::payload[
MAX_ASH_PAYLOAD_SIZE
]
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uint8_t AshRxState::payloadIndex
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uint8_t AshRxState::payloadLength
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bool AshTxDmaBuffer::resend
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uint8_t AshTxDmaBuffer::resendCount
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bool AshTxState::serialLayerReplied
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AshTxDmaBufferState
AshTxDmaBuffer::state
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