L6474 datasheet(42/51 Pages) STMICROELECTRONICS

42 / 51 page

Programming manual

L6474

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Doc ID 022529 Rev 2

The UVLO flag is active low and is set by an undervoltage lock-out or reset events (power-

up included). The TH_WRN, TH_SD, OCD flags are active low and indicate, respectively,

thermal warning, thermal shutdown and overcurrent detection events.

The NOTPERF_CMD and WRONG_CMD flags are active high and indicate, respectively,

that the command received by SPI can't be performed or does not exist at all.

The UVLO, TH_WRN, TH_SD, OCD, NOTPERF_CMD and WRONG_CMD flags are

latched: when the respective conditions make them active (low or high), they remain in that

state until a GetStatus command is sent to the IC.

The DIR bit indicates the current motor direction:

Any attempt to write to the register causes the command to be ignored and the

NOTPERF_CMD to rise (see paragraph 9.1.13).

9.2

Application commands

The commands summary is given in Table 30.

9.2.1

Command management

The host microcontroller can control motor motion and configure the L6474 through a

complete set of commands.

All commands are composed of a single byte. After the command byte, some bytes of

arguments should be needed (see Figure 15). Argument length can vary from 1 to 3 bytes.

Table 29.

STATUS register DIR bit

DIR

Motor direction

Forward

Reverse

Table 30.

Application commands

Command Mnemonic

Command binary code

Action

[7..5]

[4]

[3]

[2..1]

[0]

NOP

000

Nothing

SetParam(PARAM,VALUE)

000

[PARAM]

Writes VALUE in PARAM register

Enable

101

Enable the power stage

Disable

101

Puts the bridges in High Impedance status

immediately

GetStatus

110

Returns the status register value

RESERVED

111

RESERVED COMMAND

RESERVED

111

RESERVED COMMAND

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