 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
AT90USB646 Datasheet(PDF) 225 Page - ATMEL Corporation |
|
|
|||||||||||||||||||||||||||||
AT90USB646 Datasheet(HTML) 225 Page - ATMEL Corporation |
|
|
225 / 456 page  225 7593L–AVR–09/12 AT90USB64/128 21.8 Transmission modes The TWI can operate in one of four major modes. These are named Master Transmitter (MT), Master Receiver (MR), Slave Transmitter (ST) and Slave Receiver (SR). Several of these modes can be used in the same application. As an example, the TWI can use MT mode to write data into a TWI EEPROM, MR mode to read the data back from the EEPROM. If other masters are present in the system, some of these might transmit data to the TWI, and then SR mode would be used. It is the application software that decides which modes are legal. 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: 3 in r16,TWSR andi r16, 0xF8 cpi r16, START brne ERROR if ((TWSR & 0xF8) != START) ERROR(); Check value of TWI Status Register. Mask prescaler bits. If status different from START go to ERROR ldi r16, SLA_W out TWDR, r16 ldi r16, (1<<TWINT) | (1<<TWEN) out TWCR, r16 TWDR = SLA_W; TWCR = (1<<TWINT) | (1<<TWEN); Load SLA_W into TWDR Register. Clear TWINT bit in TWCR to start transmission of address 4 wait2: in r16,TWCR sbrs r16,TWINT rjmp wait2 while (!(TWCR & (1<<TWINT))) ; Wait for TWINT Flag set. This indicates that the SLA+W has been transmitted, and ACK/NACK has been received. 5 in r16,TWSR andi r16, 0xF8 cpi r16, MT_SLA_ACK brne ERROR if ((TWSR & 0xF8) != MT_SLA_ACK) ERROR(); Check value of TWI Status Register. Mask prescaler bits. If status different from MT_SLA_ACK go to ERROR ldi r16, DATA out TWDR, r16 ldi r16, (1<<TWINT) | (1<<TWEN) out TWCR, r16 TWDR = DATA; TWCR = (1<<TWINT) | (1<<TWEN); Load DATA into TWDR Register. Clear TWINT bit in TWCR to start transmission of data 6 wait3: in r16,TWCR sbrs r16,TWINT rjmp wait3 while (!(TWCR & (1<<TWINT))) ; Wait for TWINT Flag set. This indicates that the DATA has been transmitted, and ACK/NACK has been received. 7 in r16,TWSR andi r16, 0xF8 cpi r16, MT_DATA_ACK brne ERROR if ((TWSR & 0xF8) != MT_DATA_ACK) ERROR(); Check value of TWI Status Register. Mask prescaler bits. If status different from MT_DATA_ACK go to ERROR ldi r16, (1<<TWINT)|(1<<TWEN)| (1<<TWSTO) out TWCR, r16 TWCR = (1<<TWINT)|(1<<TWEN)| (1<<TWSTO); Transmit STOP condition (Continued) Assembly code example C example Comments |
|
Link URL |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link to Datasheet | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
