HCS410 Datasheet, PDF(16/36 Page) Microchip Technology – KEELOQ CODE HOPPING ENCODER AND TRANSPONDER

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HCS410 Datasheet, PDF (16/36 Pages) Microchip Technology – KEELOQ CODE HOPPING ENCODER AND TRANSPONDER

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HCS410

2.4.3 HCS410 RESPONSES

The responses from the HCS410 are in PPM format.

See Figure 2-17 for additional information

2.4.4 IFF RESPONSE

The 16/32-bit response to a 16/32-bit challenge, is

transmitted once, after which the device is ready to

accept another command. The same applies to the

result of a Read command. The opcode written to the

device speciï¬es the challenge length and algorithm

used.

2.4.5 IFF WRITE

The decoder can write to USER[0:3], SER[0:1], and the

conï¬guration word in the EEPROM.

After the HCS410 has written the word into the

EEPROM, it will give two acknowledge pulses (TE wide

and TE apart) on the LC pins.

When writing to the serial number or conï¬guration

word, the user must send the transport code before the

write will begin (Section 3.4) .

Note:

If the conï¬guration word is written, the

device must be reset to allow the new con-

ï¬guration settings to come into effect.

FIGURE 2-18: IFF INDUCTIVE IN RF OUT

LCI0/1

Encoder

Select ACK

Opcode

(Read)

Response

(16 bits)

2.4.6 IFF READ

The decoder can read USER[0:3], SER[0:1], and the

conï¬guration word in the EEPROM. After the data has

been read, the device is ready to receive a command

again.

Each read command is followed by a 16-bit data

response. The response always starts with a leading

preamble of 012 and then the 16-bits of data.

2.4.7 IFF PROGRAMMING

Upon receiving a programming opcode and the trans-

port code, the EEPROM is erased (Section 3.4).

Thereafter, the ï¬rst 16 bits of data can be written. After

indicating that a write command has been successfully

completed the device is ready to receive the next 16

bits. After a complete memory map was received, it will

be transmitted in PPM format on the LC pins as 16-bit

words. This enables wireless programming of the

device.

After the EEPROM is erased, the conï¬guration word is

reloaded. This results in oscillator tuning bits of 0000

being used during programming. When using IFF pro-

gramming, the user should read the conï¬guration word

and store the oscillator bits in the memory map to be

programmed. A program command should be sent and

the next set of ACK pulses transmitted by the HCS410

should be used to determine the TE. A second program

command can then be sent, and the device pro-

grammed using the TE just calibrated.

Ack

PWM

Preamble

Response

Header (32 bits) Fixed Code

(37 bits)

32-bit Response

16-bit

Response Response

DS40158C-page 16

Preliminary

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