Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet

728

SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]

11063K–ATARM–05-Nov-13

The write mode is defined as a data transmission from the master.

After a START or a REPEATED START, the decoding of the address starts. If the slave address is decoded, SVACC is
set and SVREAD indicates the direction of the transfer (SVREAD is low in this case).

Until a STOP or REPEATED START condition is detected, TWI stores the received data in the TWI_RHR.

If a STOP condition or a REPEATED START + an address different from SADR is detected, SVACC is reset.

 describes the Write operation.

Notes: 1. When SVACC is low, the state of SVREAD becomes irrelevant.

2. RXRDY is set when data has been transmitted from the shift register to the TWI_RHR and reset when this data is 

read.

The general call is performed in order to change the address of the slave.

If a GENERAL CALL is detected, GACC is set.

After the detection of General Call, it is up to the programmer to decode the commands which come afterwards.

In case of a WRITE command, the programmer has to decode the programming sequence and program a new SADR if
the programming sequence matches.

 describes the General Call access.

Note:

This method allows the user to create an own programming sequence by choosing the programming bytes and 
the number of them. The programming sequence has to be provided to the master.

RXRDY

Read RHR

SVREAD has to be taken into account only while SVACC is active

TWD

SVACC

SVREAD

EOSVACC

SADR does not match,

TWI answers with a NACK

SADR

S

ADR

W

NA

W

A

DATA

A

A

DATA

NA

S/Sr

DATA

NA

P/S/Sr

SADR matches,

TWI answers with an ACK

0000000 + W

GENERAL CALL

P

S

A

GENERAL CALL

Reset or write DADD

A

New SADR

DATA1

A

DATA2

A

A

New SADR

Programming sequence

TXD

GCACC

SVACC

RESET command = 00000110X

WRITE command = 00000100X

Reset after read