4010-DAAKF-434 Datasheet, PDF (3/14 Pages) Silicon Laboratories – Si4010 KEY FOB DEMO KIT WITH AES CAPABILITY

Si4010-Keyfob-AES-DEMO
3. Key Fob Demo with AES Capability
The 4010-DAPB RKE key fob transmitter and the Si4313 FSK receiver are the transmit and receive devices used
in this key fob demo. This transmit/receive pair can be used to evaluate the capabilities of the Si4010 transmitter
and the Si4313 receiver.
3.1. Operation of the Demo
The Si4313 demo receiver board uses the following RF parameters:
 9.6 kbps
 FSK modulation
 433.92 MHz or 868.3 MHz center frequency (menu selectable)
 ±70 kHz deviation
If any push button is pressed on the key fob, it sends a message to the receiver. The demo uses Silicon Labs'
general EZMacPRO protocol.
Table 1. General EZMacPRO Extended Packet Configuration Used by Demo Key Fobs
Preamble Synch Word
Min.13 bytes
2 bytes
MAC Header
5 bytes
MAC Payload
0...64 bytes
CRC
2 bytes
0xAA...0xAA
0x2DD4
CTRL CID SID DID PL NHDR NWK payload
CRC
3.2. Association
To enable the receiver to react to the button presses on the key fob(s), they have to be paired (i.e., the key fob has
to be associated to the receiver by pressing the left and right buttons simultaneously on the key fob).
Table 2. The MAC Payload Field of the “Associate Request from TX only Device” Packet
NHDR
MAC Payload
NWK Payload
1 byte
1 bytes
1 byte
1 byte
4 byte
4 byte
0x47
0x05
0x01
AES
Address
Rolling Counter
3.2.1. Meanings of the Different Fields
 AES—Defines whether the transmitter is using AES-128 encryption or not. It is set to 0x01; then, the Rolling
counter field of the packets is extended to 16 bytes length (12 dummy bytes are appended) and is encoded by
AES-128. Other fields of the packet are not affected by the encryption.
 Address—4 bytes of key fob address. The four byte random number factory burned in the Si4010 is used as
the address.
 Rolling Counter—The transmitter increments a 4 byte counter after every packet transmission. This counter is
stored in the MTP memory of the Si4010.
If the receiver accepts the association, it registers the Address, Master Key, and Rolling Counter value of the
requesting key fob.
The Master accepts the association if it is in pairing mode and there is a free slot for a key fob (i.e., if there are
fewer than four key fobs associated to the receiver).
After power up, the Receiver board is in pairing mode automatically. After pairing, it goes to normal packet
reception mode. The Pairing mode can be invoked by pressing the push button, PB3, on the Receiver Board. This
button needs to be pressed before the second and any subsequent pairing. If the PB is pressed for more than one
second, the receiver disassociates all key fobs.
Rev 1.1
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