HCS365 datasheet(13/34 Pages) MICROCHIP

13 / 34 page

Preliminary

DS41109D-page 13

HCS365

3.3

Seed Code Word Data Format

A seed transmission transmits a code word that con-

sists of 60 bits of fixed data that is stored in the

EEPROM. This can be used for secure learning of

encoders or whenever a fixed code transmission is

required. The seed code word contains the function

code. The seed code also contains the status informa-

tion (VLOW, CRC, and QUEUE). The Seed code word

format is shown in Figure 3-3. The function code for

seed code words is always 1111

Seed code words for Encoder 1 and Encoder 2 can be

configured as follows:

• Enabled with the Seed Button Code (SDBT) con-

figuration option or disabled if SDBT = 0000

• If the Limited Seed (SDLM) configuration option is

set, seed transmissions will be disabled when the

synchronization counter is bigger than 127. Seed

transmissions remain disabled even if the 16/20-

bit counter rolls over to 0.

• The delay before the seed transmission is trans-

mitted can be set to 0.0s, 0.8s, 1.6s and 3.2s with

the Seed Time (SDTM) configuration option.

When SDTM is set to a value other than 0.0s, the

HCS365 will transmit a code hopping transmis-

sion until the selected time expires. After the

selected time expires, the seed code words are

transmitted. This is useful for the decoder to learn

the serial number and the seed from a single but-

ton press.

• The button code for transmitting a seed code

word can be selected with the Seed Button

(SDBT) configuration option. SDBT bits 0 to 3 cor-

respond to button inputs S0 to S3. Set the bits

high for the button combination that should trigger

a seed transmission (i.e., If SDBT = 1010

2 then,

S3+S1 will trigger a seed transmission).

• The seed transmissions before the counter incre-

ments past 128 can be modified with the Seed

Mode (SDMD) configuration option. Setting this

bit for Production mode will cause the selected

seed button combination to first transmit a normal

hopping code word for the selected Minimum

Code words (MTX) and then at least MTX seed

code words until all buttons are released. This

mode is disabled after the counter reaches 128

even if the 16/20-bit counter rolls over to 0.

• The limit of 127 for SDLM or SDMD can be

reduced by using an initial counter value >0.

FIGURE 3-3:

SEED CODE WORD FORMAT

Note:

The synchronization counter only incre-

ments on code hopping transmissions.

The counter will not advance on a seed

transmission unless Seed Delay or Pro-

duction mode options are on.

Transmission Direction LSB First

Open Portion (Not Encrypted)

QUE

(2 Bits)

CRC

(2 Bits)

VLOW

(1-Bit)

SEED

With QUEN = 1

Function

(4 Bits)

(9 bits)

SEED Code

(60 bits)

Q1 Q0 C1 C0

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