MDEV-868-PRC datasheet(22/55 Pages) LINX

22 / 55 page

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Writing to Registers

To allow any byte value to be written, values of 128 (0x80) or greater can

be encoded into a two-byte escape sequence of the format 0xFE, [value

- 0x80]. This includes register addresses as well as values to be written to

the registers. The result is that there are four possible packet structures

because of the possible escape sequences. These are shown in Figure 29.

Generally, there are three steps to creating the command.

1. Determine the register address and the value to be written.

2. Encode the address and value as either the number (N) or the encoded

number (0xFE, N-0x80) as appropriate.

3. Add the header (0xFF) and the size.

The module responds with an ACK (0x06). If the ACK is not received, the

command should be resent. The module responds with a NACK (0x15) if a

write is attempted to a read-only or invalid register.

As an example, to write 01 to register 0x83, send

FF 03 FE 03 01

Figure 29: HumPRCTM Series Write to Configuration Register Command

HumPRCTM Series Write to Configuration Register Command

Header

Size

Address

Value

0xFF

0x02

REG

Header

Size

Address

Escape

Value

0xFF

0x03

REG

0xFE

V-0x80

Header

Size

Escape

Address

Value

0xFF

0x03

0xFE

REG-0x80

Header

Size

Escape

Address

Escape

Value

0xFF

0x04

0xFE

REG-0x80

0xFE

V-0x80

Note: The non-volatile memory has a life expectancy with a limited

number of refresh cycles. Please see the electrical specifications.

Command Length Optimization

Some commands may be shortened by applying the following rules:

1. Escape sequences are not required for byte values 0x00 to 0xEF

(besides 0xFE and 0xFF, bytes 0xF0 – 0xFD are reserved for future

use).

2. An escape byte inverts bit 7 of the following data byte.

3. The 0xFE as the first byte of the Read Register Command field is an

escape byte.

4. Two consecutive escape bytes cancel unless the following data byte

is 0xf0-0xff.

Examples:

• FF 02 FE 02 (read nv:TXPWR) is equivalent to FF 01 82.

• FF 03 FE FE 53 (read v:PKOPT) is equivalent to FF 01 53.

• FF 03 1A FE 7F (write FF to nv:UMASK0) cannot be shortened.

• FF 03 1A FE 40 (write C0 to nv:UMASK0) is equivalent to FF 02 1A

C0.

These rules are implemented in the sample code file EncodeProCmd.c,

which can be downloaded from the Linx website.

MDEV-868-PRC 데이터시트(PDF) 22 Page - Linx Technologies

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