HCS412 datasheet(24/52 Pages) MICROCHIP

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HCS412

DS41099D-page 24

4.3.4

BULK ERASE

A Bulk Erase resets the HCS412’s memory map to all

zeros. The transponder reader selects the appropriate

device through anticollision, as need be, issues the

PROGRAM

command followed by the device’s 28-bit

transport code, then resets the device by removing the

field for 100 ms.

Resetting the device after the PROGRAM command

results in a bulk erase, resetting the EEPROM memory

map to all zeros. This is important to remember as the

reader must now communicate to the device using the

communication options resulting from a zero’d configu-

ration word - baud rates, modulation format, etc.

(Table 5-1).

FIGURE 4-7:

BULK ERASE

4.3.5

PROGRAM

Inductive programming a HCS412 begins with a bulk

erase sequence (Section 4.3.4), followed by issuing

the PROGRAM command and the desired EEPROM

memory map’s 18x16-bit words (Section 5.0). The

HCS412 will send a write Acknowledge after each word

has been successfully written, indicating the device is

ready to receive the next 16-bit word.

After a complete 18 word memory map has been

received and written, the HCS412 PPM modulates 18

bursts of 16-bit words on the LC pins for write verifica-

tion. Each word follows the standard HCS412 response

format with a leading 1LFTE low START pulse and ‘01b’

preamble (Figure 4-10).

Since the bulk erase resets the configuration options to

all zeros, the oscillator tuning value will also be cleared.

The correct tuning value is required when the program-

ming sequence sends the new configuration word. The

value may either be obtained by reading the configura-

tion word prior to bulk erase to extract the value or by

determining TE from the field Acknowledge sequence

and calculating the tuning value appropriately

(Section 4.2.1).

TABLE 4-6:

PROGRAM COMMANDS

FIGURE 4-8:

PROGRAM SEQUENCE - FIRST WORD

Transport

Code

28-bit

100ms

Program

TOTD

Communication from reader to HCS412

Communication from HCS412 to reader

Start

2 LFTE

Start

2 LFTE

ACK

6ms

TPU

TATO

Activate

Field

ACK

Delay to

Command

Delay to

TCODE

Transport

28-bit

Delay

Code

Device Reset

Command

Description

Expected data In

Response

01000

Program HCS412 EEPROM

Transport code (28 bits); Com-

plete memory map: 18 x 16-bit

words (288 bits)

Write Acknowledge pulse after

each 16-bit word, 288 bits trans-

mitted in 18 bursts of 16-bit words

Activate

Field

ACK

Delay to

Command

Delay to

TCODE

Transport

Write ACK

Delay before Write

ACK

28-bit

Delay to

Data

Code

16 bits Data

Repeat 18 times for programming

Transport

Code

28-bit

TWR

Program

TOTD

Write Delay

Communication from reader to HCS412

Communication from HCS412 to reader

Start

2 LFTE

Start

2 LFTE

Start

2 LFTE

ACK

TTTD

TPU

TATO

Command

Data Bits

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