L6364 datasheet(20/60 Pages) STMICROELECTRONICS

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In SIOListen mode a received UART frame is only reported if the parity and stop bits are correct. The

microcontroller must switch from SIO mode to IO-Link mode after reception of a valid UART frame before

responding with LINK:END, otherwise the L6364 returns to SIO mode conflicting with the further master

transmission.

8.2.3

Transmit mode

Transmit mode is entered when the microcontroller writes FR0 while the L6364 is in the Receive wait state.

The UART reads this value from the FR0 register, emptying the buffer, and starts transmitting. The L6364 enters

the Transmit wait state.

The L6364 provides a single octet data buffer and requests further data whenever this buffer is empty, including

during the transmission of the previous octet. It is only necessary to ensure that this buffer is refilled before the

UART needs to send the next octet.

The maximum allowed time between the starts of two subsequent frames on IO-Link is 11 TBIT frame + 3 TBIT

pause = 14 TBIT, which at 230.4kBaud gives a period of 60 μs for the 16 bit SPI access. At 4 MHz SPI this

corresponds to an SPI delay of 4 μs.

In Transmit mode the L6364 has the following states:

•

Transmit wait: The L6364 requests a new octet by sending a data interrupt (STATUS:DAT='1').

The L6364 is waiting for a response from the microcontroller, which either writes FR0 with a new octet to

continue transmission, or LINK:END to terminate transmission.

•

Transmitting (buffer empty): The UART sends the current octet.

A further response is requested from the microcontroller, by sending a data interrupt (STATUS:DAT='1'). If

the microcontroller provides a further octet, this is placed in the buffer and the state changes to Transmitting

(buffer full), if the microcontroller writes LINK:END, then the state changes to Transmitting (terminating).

If the microcontroller does not provide an octet before the UART transmission completes, then the state

changes to Transmit wait.

•

Transmitting (buffer full): The UART sends the current octet. On completion, it sources the next octet from

the buffer, and the state changes to Transmitting (buffer empty).

•

Transmitting (terminating): The UART sends the current octet. On completion, the PHY returns to idle.

8.2.4

Timing errors in transmit

The microcontroller can cause a timing error in Transmit mode if the delay in response is too long. These errors

are not monitored by the L6364. A minimum inter-frame time delay of 1xTBIT is, however, guaranteed by the

L6364.

8.2.5

Error condition in transmit

Error conditions are reported to the microcontroller as either short-circuit (STATUS:SSC='1', reported following a

delay of tRETRY), or overtemperature (STATUS:SOT='1').

The conditions are handled autonomously by the L6364 and no intervention by the microcontroller is necessary.

The normal data flow is preserved and the L6364 requests further octets from the microcontroller as if the error

were not present.

These octets are silently dropped and no attempt is made to transmit them. Under error conditions, then

transmission may be terminated by the microcontroller using LINK:END='1'.

L6364

Single octet UART mode

DS13363 - Rev 4

page 20/60

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