Modes¶

Unrelated¶

• Send CAN messages as Broadcast messages; fire and forget
• Good enough for sensor values
• Robust code, not much that can fail
• Not good enough for e.g. Flashing firmware on remote device or even scanning nodes.

Related¶

• Each package need an acknowledge
• Retransmitts are send if acknowledge is missing
• Heavy traffic if nodes are blocking each other.
• Complex code, but ok
• Order may not be guearanteed / optional

Related¶

Retransmits¶

• In starting phase there is an auto-tune which requires traffic
• There are at least some CRC errors

Send package¶

• ringTransmitted.canPush()?
• store essage there
• Send it via RFM69

Receive package¶

• If type is "Acknowledge"
  • find corresponding message
  • mark slot as acked/nacked

• If regular message/resend
  • If resend: is the package older than the last?, drop it
  • is it not last+1? send NACK via RFM69
  • fill it in the receive buffer
  • directly send acknowledge via RFM69

Loop¶

• iterate Slots
• If WAITing: is message is older than ??ms, perform an resend
• If ACKed, pop it from the ring. Not the first non-ACKed? Error
• If NACKed, resend it, if there is no WAITing before

Open points¶

• Acknowledge gets lost; retransmit started
  • last-id for every net. Drop message if it matches

• RFM-Class receives messages in ISR as fast as possible. Sending acknowledge is done in the loop.
  • Order should be preserved.
  • Makes things super slow

State machine¶

Sender event loop¶

• Each node sends a heartbeat every 5 seconds with the current message counter.
• A node has a list of (expected) package counter of other devices
• When a node received a message via can, it sends it as broadcast and sets the open-ack-mask to the node-mask
• If there was no ACK after 10ms, send retransmit to each Ack-missing node.
• If there was no ACK after 10 Seconds, remove remaing nodes from Node-List.
• If there is no Heartbeat from a Node for 1 Minute, remove node from

Receiver Event loop¶

• When receiving a message via radio with correct order, an acknowledge is send immediately. Process and drop the message.
• When receiving a message via radio with to low order, send an acknowledge again and drop the message.
• When receiving a message via radio with too high order, act like in (1), but warn becuase of lost message.