Datasheet

In Master Receiver mode, the slave calculates a PEC value and transmits it to the master after all data bytes have

been transmitted. Upon reception of this PEC byte, the master compares it to the PEC value it has computed itself. If

the values match, the data was received correctly

. If the PEC values differ, data was corrupted, and

TWIHS_SR.PECERR is set. In Master Receiver mode, the PEC byte is always followed by a NACK transmitted by

the master, since it is the last byte in the transfer.

In combined transfers, the PECRQ bit should only be set in the last of the combined transfers.

Consider the following transfer:

S, ADR+W, COMMAND_BYTE, ACK, SR, ADR+R, DATA_BYTE, ACK, PEC_BYTE, NACK, P

See Read/Write Flowcharts for detailed flowcharts.

43.6.3.9.2 Timeouts

The TLOWS and TLOWM fields in TWIHS_SMBTR configure the SMBus timeout values. If a timeout occurs, the

master transmits a STOP condition and leaves the bus. The TOUT bit is also set in TWIHS_SR.

43.6.3.10 SMBus Quick Command (Master Mode Only)

The TWIHS can perform a quick command by following these steps:

1. Configure the Master mode (DADR, CKDIV, etc).

2. Write TWIHS_MMR.MREAD at the value of the one-bit command to be sent.

3. Start the transfer by setting TWIHS_CR.QUICK.

Figure 43-13. SMBus Quick Command

TXCOMP

TXRDY

Write QUICK command in TWIHS_CR

TWD

AS DADR R/W P

43.6.3.11 Read/Write Flowcharts

The flowcharts give examples for read and write operations. A polling or interrupt method can be used to check the

status bits. The interrupt method requires that TWIHS_IER be configured first.

SAM E70/S70/V70/V71 Family

wo-wire Interface (TWIHS)

echnology Inc.

Datasheet

DS60001527D-page 1054