MDEV-868-PRC datasheet(21/55 Pages) LINX

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The Command Data Interface

The HumPRCTM Series transceiver has a serial Command Data Interface

(CDI) that is used to configure and control the transceiver through

software commands. This interface consists of a standard UART with a

serial command set. The CMD_DATA_IN and CMD_DATA_OUT lines are

the interface to the module’s UART. The UART is configured for 1 start

bit, 1 stop bit, 8 data bits, no parity and a serial data rate set by register

UARTBAUD (default 9,600bps).

Configuration settings are stored in two types of memory inside the

module. Volatile memory is quick to access, but it is lost when power is

removed from the module. Non-volatile memory has a limited number of

write cycles, but is retained when power is removed. When a configuration

parameter has both a non-volatile and volatile register, the volatile register

controls the operation unless otherwise stated. The non-volatile register

holds the default value that is loaded into the volatile register on power-up.

Configuration settings are read from non-volatile memory on power up

and saved in volatile memory. The volatile and non-volatile registers have

different address locations, but the same read and write commands. The

two locations can be changed independently.

The general serial command format for the module is:

[FF] [Length] [Command]

The Length byte is the number of bytes in the Command field. The

Command field contains the register address that is to be accessed and,

in the case of a write command, the value to be written. Neither Length nor

Command can contain a 0xFF byte.

Byte values of 128 (0x80) or greater can be sent as a two-byte escape

sequence of the format:

0xFE, [value - 0x80]

For example, the value 0x83 becomes 0xFE, 0x03. The Length count

includes the added escape bytes.

A response is returned for all valid commands. The first response byte is

CMD_ACK (0x06) or CMD_NACK (0x15). Additional bytes may follow, as

determined by the specific command.

Reading from Registers

A register read command is constructed by placing an escape character

(0xFE) before the register number. The module responds by sending an

ACK (0x06) followed by the register number and register value. The register

value is sent unmodified, so if the register value is 0x83, 0x83 is returned.

If the register number is invalid, the module responds with a NACK (0x15).

The command and response are shown in Figure 28.

Figure 28: HumPRCTM Series Read from Configuration Register Command and Response

HumPRCTM Series Read From Configuration Register

Command

Header

Size

Escape Address

0xFF

0x02

0xFE

REG

Response

ACK

Address

Value

0x06

REG

Command for an Address greater than 128 (0x80)

Header

Size

Escape

Addr1

Addr2

0xFF

0x03

0xFE

REG-80

Response

ACK

Address

Value

0x06

REG

MDEV-868-PRC Datasheet(PDF) 21 Page - Linx Technologies

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