Play with AAP

    /""\ ???
c{@..@}ↄ
(__)

  Available monkeys nodes on the virtual liana bus : 

  @,2,3,5,9,a,c,d,e,g,i,k,l,s,x,y,A,B,F,G,J,L,N,O,P,R,T,U,V,W,X,Y,Z

Frame :

BRK : >10bits dominant (low) signal (13bits recommended)

U = 0x55 = 0b01010101: SYNC

Address [alphanum or @ or *] Command

CRC (ctrl->node) = base64:'X' = 0x17

reply (formatted & w/o CRC and "\n")

"\n" = <LF> = 0x0A : end of frame

Sending a broadcast request is allowed if only one node is connected! (Collision risk : should be prohibited for operational implementation and strictly reserved for testing purposes.)

The address `@` should be considered the default address for a new module and changed by the controller to assign it an alphanumerical address ~~(so the monkey knows who he is)~~ using the change address [`A!`] command. Polling this `@` allows user to find a new node easily and economically.

 @M!X

AAP Protocol

Note : The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

Physical layer

The physical layer is voluntarily unconstrained. Nevertheless :

The protocol was designed to work on a LIN physical layer which is thus RECOMMENDED : cable architecture is simple, necessary voltage (about 12V) usually available on targeted applications, hardware is cheap, widely available and robust (led by automotive industry).
Other physical layers MAY be used : RS-485, RS-232, TTL levels, … as long as special care is given to the architecture and the relationship between the used baudrate and the physical line.
Communication SHOULD be half-duplex.

Datalink layer

Data MUST be represented as common 8N1 serial data.
The RECOMMENDED baudrate is 19200. Other baudrate MAY be used, taking care of proper timing/detection in node modules and physical layer capabilities.
Every frame MUST start with a BREAK signal, sent by controller. That BREAK signal MUST be at least 11 bits long, minimal RECOMMENDED length is 13 bits, maintaining the line in its 0 or dominant level.
Every BREAK signal MUST be followed by a SYNC character consisting in value 0x55 = ASCII('U'), sent by controller.
The controller MUST then send the address of the targeted node(s).
The address MUST be a printable ASCII character, and SHOULD be an alphanumerical or @ character {0-9, A-Z, a-z, @} to target a specific node or 0x2A = ASCII ('*') wildcard character to target all the nodes at the same time. Other printable characters MAY be used if absolutely necessary.
The controller MAY then send any ASCII readable "message".
The controller MUST then send a "term character" being either a ! character if no reply is expected from the targeted node(s) or a ? character if a reply is expected from the targeted node(s).
After the communication message, the controller MUST send a fixed-length CRC of (address + message + term character) as ASCII readable char(s).
Every reply (except empty) from the target node MUST be followed by the CRC of the full reply. The CRC algorithm MUST be the same as the one used for the controller.
Every frame MUST end with a 0x0A = ASCII ('\n') character, sent by either controller (if the controller doesn't expect the targeted node to answer or addressing all nodes) or by node (otherwise).

Application layer

Orders

M! : Start measurement

Start measurement. This function only ask the node to measure value(s), without sending it. Use `D?` or `d?` to collect data.

R! : Continuous measurement

Ask the node to take measurement(s) continuously (without sending them).

x! : Disable measurements values

Will make the node reply a null for every value.

X! : Reset measurements values.

Will make the node take measurements normally back again.

A! : Change address

Change the current node address.
RFC2119 specifications :
The change address command MUST contain the new address to be assigned after the `A` and before the order closure `!` and is thus of the form Ax! where x is the new address to assign to the node.

S! : Go to sleep

Go to sleep.

Requests

? : Adress ACK

Acknowledge the tested address.
RFC2119 specifications :
This command MUST NOT generate any reply.

I? : Send identifier

Send identifier.
RFC2119 specifications :
This identifier :

SHOULD have an id key describing an ID/Serial Number of the module, unique at the institution/enterprise/user level.
MUST have a m key containing an object (or an array of objects if multiple measurements in the same node) that :
- MUST have a n [name] key describing the measurement name as a string. That name SHOULD be unique in the network and MUST be unique in the node.
- SHOULD have a u [unit] key describing unit as a string, or two keys u and pu describing electrical and physical units respectively.
- If u and pu are provided, a tf [transfer function] MUST also be provided as an algebraic expression giving p [physical value] as a function of v [value].
MAY have have other keys, freely decided by user, that MUST be kept constant between measurements.

D? : Send data [extended]

Send data [extended].
RFC2119 specifications :
MUST return the same object as the "Send Identifier" [I?] reply, with additional key v in m object (or in each object in m if m is an array of objects).
This v key MUST contain the measurement represented as a valid JSON number or null.

d? : Send data [short]

Send value (or array of values) reprensenting the data.
RFC2119 specifications :
Data MUST be presented in the very same order as in "Send Identifier" [I?] reply if multiple.
Each data MUST be a valid JSON number or null.