HCS361-IP Microchip Technology, HCS361-IP Datasheet - Page 6

• Manufacturer Part Number: HCS361-IP
• Description: KEELOQ CODE HOPPING ENCODER
• Manufacturer: Microchip Technology

HCS361
3.2
This is the 16-bit synchronization value that is used to
create the hopping code for transmission. This value
will be changed after every transmission. A second syn-
chronization value can be used to stay synchronized
with a second receiver.
3.3
This is the three word (48 bits) seed code that will be
transmitted when seed transmission is selected. This
allows the system designer to implement the secure
learn feature or use this fixed code word as part of a dif-
ferent key generation/tracking process or purely as a
fixed code transmission.
3.4
SER_0 and SER_1 are the lower and upper words of
the device serial number, respectively. There are 32 bits
allocated for the serial number and a selectable config-
uration bit determines whether 32 or 28 bits will be
transmitted. The serial number is meant to be unique
for every transmitter.
3.5
The configuration word is a 16-bit word stored in
EEPROM array that is used by the device to store
information used during the encryption process, as well
as the status of option configurations. Further
explanations of each of the bits are described in the
following sections.
DS40146C-page 6
SYNC_A, SYNC_B
(Synchronization Counter)
SEED_0, SEED_1, and SEED_2
(Seed Word)
SER_0, SER_1 (Encoder Serial
Number)
CONFIG (Configuration Word)
Preliminary
TABLE 3-2
3.5.1
BACW = 1 selects the encoder to transmit every sec-
ond code word. This can be used to reduce the average
power transmitted over a 100ms window and thereby
transmit a higher peak power.
3.5.2
FAST selects the baud rate. If FAST = 1, the baud rate
is nominally 1667 bits per second and with FAST = 0,
833 bits per second.
3.5.3
In PWM mode, this bit selects the bit format. If TXWAK
= 1, the PWM pulse is 1/6;2/6 and for TXWAK = 0, 1/
3;2/3 (Figure 4-1, VPWM = 0).
In VPWM mode, this bit enables the wake-up signal.
With TXWAK = 1, transmission of the wake-up and
dead time sequence is enabled (Figure 4-2, VPWM =
1). Wakeup is transmitted before the first code word of
each transmission only. For TXWAK = 0, the transmis-
sion will skip wake-up and start transmitting the pream-
ble portion of the code word (Figure 4-2, VPWM = 1).
3.5.4
Select modulation mode of Sync Pulse. If SPM = 1, the
sync pulse is modulated (Figure 4-1 and Figure 4-2).
Bit Number Symbol
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
BACW: BLANK ALTERNATE CODE WORD
FAST: SELECT FAST TRANSMISSION
TXWAK: BIT FORMAT SELECT OR
WAKEUP
SPM: SYNC PULSE MODULATION
TXWAK PWM mode: 1/6, 2/6 or 1/3,
TMPSD
USRA0
USRA1
USRB0
USRB1
VPWM
BACW
SEED
DELM
XSER
FAST
TIMO
SPM
OVR
IND
CONFIGURATION WORD
Blank Alternate Code Word
1996 Microchip Technology Inc.
Seed Transmission enable
Independent mode enable
Temporary seed transmis-
Extended serial number
Sync Pulse Modulation
VPWM mode: Wakeup
Baud Rate Selection
Delay mode enable
Time out enable
Bit Description
VPWM select
Overflow bit
sion enable
2/3 select
User bit
User bit
User bit
User bit
enable
enable