Datasheet

Page 24 of 161
nRF8001 Product Specification
Revision 1.2
7.1.5 ACI event exchange
Figure 11. shows the signaling in an ACI event exchange from nRF8001 to the application controller.
Figure 11. Receiving an ACI event from nRF8001
The application controller receives the ACI event by performing the following procedure:
1. nRF8001 sets the RDYN pin to ground.
2. The application controller sets the REQN pin to ground and starts clocking on the SCK pin.
• Byte 1 (debug byte) from nRF8001 is an internal debug byte and the application
controller discards it.
• Byte 2 (length byte) from nRF8001 defines the length of the message.
• Byte 3 (ACI byte1) is the first byte of the ACI data.
• Byte N is the last byte of the ACI data.
3. The application controller sets the REQN pin high to close the event.
Note: The maximum length of an event packet is 31 bytes, including the length byte.
7.1.6 ACI full-duplex transaction
nRF8001 is capable of receiving an ACI command simultaneously as it sends an ACI event to the
application controller.
The application controller shall always read the length byte from nRF8001 and check if the length is
greater than 0. If the length is greater than 0 the data on the MISO line shall be read as described in
section 7.1.5
.
An ACI event received from the nRF8001 processor is never a reply to a command being simultaneously
transmitted. For all commands, the corresponding event will always be received in a subsequent ACI
transaction.
MISO
MOSI
REQN
SCK
RDYN
debug byte length byte ACI byte1
Slave ready
End of
transmission
ACI byteN
....
....
....