Acknowledgements

Some message codes require an acknowledgement from the receiver. In this case, the receiver should send either an acknowledgement (ACK) or negative-acknowledgement (NAK) within 1 second of receiving the message.

Acknowledgments should be sent directly after message is received so that the sender can act accordingly. An acknowledgment should contain the message group , code and current state for the message that it is referencing. For example, if the Provider receives a message containing the ring action ( 0x04010002013C ), it should acknowledge the action by sending back 0xFF0100040401013C where:

• 0xFF: ACK event
• 0x01: ACK code
• 0x0004: Additional data length
• 0x0401: The action message group and code
• 0x013C: The current state of the action message group and code, ring right and 60 seconds timeout

For a NAK, the reason should also be included as the first byte of additional data. Reasons include:

• 0x00: Not supported
• 0x01: Device busy
• 0x02: Not allowed due to current state
• 0x03: Not allowed due to incorrect message authentication code
• 0x04: Redundant device action

From the previous example, if the ring were to be NAK'ed instead due to the Provider being busy with another task, the returned packet should be set to 0xFF02000401040100 where

• 0xFF: ACK event
• 0x02: NAK code
• 0x0004: Additional data length
• 0x01: NAK reason, Device busy
• 0x0401: The action message group and code
• 0x00: The current state of the action message group and code, all components stop ringing

Example:

  #define FP_MSG_ACK                                  0x01 
 #define FP_MSG_NAK                                  0x02 
 #define FP_MSG_GROUP_ACK                            0xFF 
 static 
  
 void 
  
 fp_msg_send_ack 
 ( 
 uint8_t 
  
 msgGroup 
 , 
  
 uint8_t 
  
 msgCode 
 ) 
 { 
  
 FP_MESSAGE_STREAM 
  
 req 
  
 = 
  
 { 
 FP_MSG_GROUP_ACK 
 , 
  
 FP_MSG_ACK 
 , 
  
 0 
 , 
  
 2 
 }; 
  
 req 
 . 
 data 
 [ 
 0 
 ] 
  
 = 
  
 msgGroup 
 ; 
  
 req 
 . 
 data 
 [ 
 1 
 ] 
  
 = 
  
 msgCode 
 ; 
  
 fp_send 
 (( 
 uint8_t 
  
 * 
 ) 
& req 
 ); 
 } 
 static 
  
 void 
  
 fp_msg_send_nak 
 ( 
 uint8_t 
  
 reason 
 , 
  
 uint8_t 
  
 msgGroup 
 , 
  
 uint8_t 
  
 msgCode 
 ) 
 { 
 //reason= 0x00: Not supported, 0x01: Device busy, or 0x02: Not allowed due to current state 
  
 FP_MESSAGE_STREAM 
  
 req 
  
 = 
  
 { 
 FP_MSG_GROUP_ACK 
 , 
  
 FP_MSG_NAK 
 , 
  
 0 
 , 
  
 3 
 }; 
  
 req 
 . 
 data 
 [ 
 0 
 ] 
  
 = 
  
 reason 
 ; 
  
 req 
 . 
 data 
 [ 
 1 
 ] 
  
 = 
  
 msgGroup 
 ; 
  
 req 
 . 
 data 
 [ 
 2 
 ] 
  
 = 
  
 msgCode 
 ; 
  
 fp_send 
 (( 
 uint8_t 
  
 * 
 ) 
& req 
 ); 
 }