HCS410_11 Datasheet, PDF(15/46 Page) Microchip Technology – KEELOQ® Code Hopping Encoder and Transponder 2-bit CRC, 2-bit queue

English

English German Russian Spanish Italian Polish Chinese Japanese Korean French Portuguese	Language :

HCS410_11 Datasheet, PDF (15/46 Pages) Microchip Technology – KEELOQ® Code Hopping Encoder and Transponder 2-bit CRC, 2-bit queue

◁

2.4.3 HCS410 RESPONSES

The responses from the HCS410 are in PPM format.

See Figure 2-17 for additional information. Every

response from the HCS410 is preceded by a â2 bit pre-

ambleâ of 012, and then 16/32 bits of data.

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 specifies the challenge length and algorithm

used. The response always starts with a leading pre-

amble of 012 followed by the 16/32 bits of data.

2.4.5 IFF WRITE

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

configuration 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 configuration

word, the user must send the transport code before the

write will begin (Section 3.4) .

Note:

If the configuration word is written, the

device must be reset to allow the new con-

figuration settings to come into effect.

HCS410

2.4.6 IFF READ

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

configuration 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). There-

after, the first 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 configuration 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 configuration 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.

DS40158F-page 15

▷