MRF24XA_15 Datasheet, PDF (95/258 Pages) Microchip Technology – Low-Power, 2.4 GHz ISM-Band IEEE 802.15.4™ RF

MRF24XA
FIGURE 4-4:
WIRELESS SENDING: EXAMPLE SCENARIO (MESSAGE SEQUENCE CHART)
Originator Node
Recipient Node
TX Host
MCU
SPI, INTn
1
TX Configuration
(AUTOACKEN=1)
2 payload
4
MHR
(SecEn=1)
(AckReq=1)
5
Load buffer
TX
Device
Medium
RX
Device
SPI, INTn
RX Host
MCU
= When ACK required
then device handles it
AckReq = Acknowledge
required for this frame
RX Configuration
(AUTOACKEN=1)
RXEN 1
1
3
Wait for
RXIF
interrupt
Security Key
6
TXST 1
7
Wait for
confirmation
interrupt
ACK time-out
16
Confirmation
done
ACK received
TXIF=1, TXST 0
(Interrupt Serviced)
Get AckReq, SecEn
Encrypt
FCS Append
8 _{CSMA, Send}
9 ^{FCS Check}
(Accepted)
Send ACK
10
RXBUFFULL=1
?
RXIF
13 CSMA, Resend
Read MHR
15
New state
depends
on RXEN
14 Duplicate !
Send ACK
RXEC, Security Key
Decrypt
Decryption
complete
17
RXDECIF
11
12
SecEn=1
Wait for
RXDEC
interrupt
Interrupt
Serviced
Buffer unlocked
Wait for new frame
Read Payload
RXBUFFULL 0
18
Free the buffer
Wait for
new frame
In-place processing (whether transmitting or receiving-
side) is tested using a single node. This is useful in
device testing or software troubleshooting. Figure 4-5
illustrates the procedure of in-place test using a single
node. Note that the Originator and the Recipient node
can be the same hardware.
TXBUF1PP triggers the processing that TXST origi-
nally performs. TXIF interrupt is generated at the end of
in-place processing, without attempting to physically
send the frame. The device clears TXBUF1PP at the
same time.
 2015 Microchip Technology Inc.
Preliminary
DS70005023C-page 95