HCS360 datasheet(7/40 Pages) MICROCHIP

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DS40152F-page 7

HCS360

3.5

CONFIG

(Configuration Word)

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.

TABLE 3-2:

CONFIGURATION WORD.

3.5.1

MOD: MODULATION FORMAT

MOD selects between Manchester code modulation

and PWM modulation.

If MOD = 1, Manchester modulation is selected:

If MOD = 0, PWM modulation is selected.

3.5.2

BSEL 1, 0

BAUD RATE SELECTION

BSEL 1 and BSEL 0 determine the baud rate according

to Table 3-3 when PWM modulation is selected.

TABLE 3-3:

BAUD RATE SELECTION

BSEL 1 and BSEL 0 determine the baud rate according

to Table 3-4 when Manchester modulation is selected.

TABLE 3-4:

BAUD RATE SELECTION

3.5.3

OVR: OVERFLOW

The overflow bit is used to extend the number of possi-

ble synchronization values. The synchronization coun-

ter is 16 bits in length, yielding 65,536 values before the

cycle repeats. Under typical use of 10 operations a day,

this will provide nearly 18 years of use before a

repeated value will be used. Should the system

designer conclude that is not adequate, then the over-

flow bit can be utilized to extend the number of unique

values. This can be done by programming OVR to 1 at

the time of production. The encoder will automatically

clear OVR the first time that the transmitted synchroni-

zation value wraps from 0xFFFF to 0x0000. Once

cleared, OVR cannot be set again, thereby creating a

permanent record of the counter overflow. This pre-

vents fast cycling of 64K counter. If the decoder system

is programmed to track the overflow bits, then the effec-

tive number of unique synchronization values can be

extended to 128K. If programmed to zero, the system

will be compatible with old encoder devices.

3.5.4

LNGRD: LONG GUARD TIME

LNGRD = 1 selects the encoder to extend the guard

time between code words adding

≈ 50 ms. This can be

used to reduce the average power transmitted over a

100 ms window and thereby transmit a higher peak

power.

Bit Number Symbol

Bit Description

LNGRD

Long Guard Time

BSEL 0

Baud Rate Selection

BSEL 1

Baud Rate Selection

3NU

Not Used

SEED

Seed Transmission enable

DELM

Delay mode enable

TIMO

Time-out enable

IND

Independent mode enable

USRA0

User bit

USRA1

User bit

USRB0

User bit

USRB1

User bit

XSER

Extended serial number

enable

TMPSD

Temporary seed transmis-

sion enable

MOD

Manchester/PWM modula-

tion selection

OVR

Overflow bit

MOD

BSEL 1 BSEL 0

Unit

400

200

100

MOD

BSEL 1 BSEL 0

Unit

800

400

200

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