Atmel ATmega328P Xplained Mini MEGA328P-XMINI MEGA328P-XMINI Scheda Tecnica
Codici prodotto
MEGA328P-XMINI
218
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
Atmel-8271H-AVR- ATmega-Datasheet_08/2014
The following sections describe each of these modes. Possible status codes are described along with figures
detailing data transmission in each of the modes. These figures contain the following abbreviations:
detailing data transmission in each of the modes. These figures contain the following abbreviations:
S: START condition
Rs: REPEATED START condition
R: Read bit (high level at SDA)
W: Write bit (low level at SDA)
A: Acknowledge bit (low level at SDA)
A: Not acknowledge bit (high level at SDA)
Data: 8-bit data byte
P: STOP condition
SLA: Slave Address
, circles are used to indicate that the TWINT Flag is set. The numbers in the
circles show the status code held in TWSR, with the prescaler bits masked to zero. At these points, actions must
be taken by the application to continue or complete the TWI transfer. The TWI transfer is suspended until the
TWINT Flag is cleared by software.
be taken by the application to continue or complete the TWI transfer. The TWI transfer is suspended until the
TWINT Flag is cleared by software.
When the TWINT Flag is set, the status code in TWSR is used to determine the appropriate software action. For
each status code, the required software action and details of the following serial transfer are given in
each status code, the required software action and details of the following serial transfer are given in
. Note that the prescaler bits are masked to zero in these tables.
22.7.1 Master Transmitter Mode
In the Master Transmitter mode, a number of data bytes are transmitted to a Slave Receiver (see
In order to enter a Master mode, a START condition must be transmitted. The format of the following address
packet determines whether Master Transmitter or Master Receiver mode is to be entered. If SLA+W is
transmitted, MT mode is entered, if SLA+R is transmitted, MR mode is entered. All the status codes mentioned
in this section assume that the prescaler bits are zero or are masked to zero.
packet determines whether Master Transmitter or Master Receiver mode is to be entered. If SLA+W is
transmitted, MT mode is entered, if SLA+R is transmitted, MR mode is entered. All the status codes mentioned
in this section assume that the prescaler bits are zero or are masked to zero.
Figure 22-11. Data Transfer in Master Transmitter Mode
A START condition is sent by writing the following value to TWCR:
TWEN must be set to enable the 2-wire Serial Interface, TWSTA must be written to one to transmit a START
condition and TWINT must be written to one to clear the TWINT Flag. The TWI will then test the 2-wire Serial
condition and TWINT must be written to one to clear the TWINT Flag. The TWI will then test the 2-wire Serial
TWCR
TWINT
TWEA
TWSTA
TWSTO
TWWC
TWEN
–
TWIE
value
1
X
1
0
X
1
0
X
Device 1
MASTER
TRANSMITTER
Device 2
SLAVE
RECEIVER
Device 3
Device n
SDA
SCL
........
R1
R2
V
CC