 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
X24257B-2.5 Datasheet(PDF) 7 Page - Xicor Inc. |
|
||||||||||||||||||||||||||||||
X24257B-2.5 Datasheet(HTML) 7 Page - Xicor Inc. |
|
|
7 / 19 page  X24257 – Preliminary Information Characteristics subject to change without notice. 7 of 19 REV 1.1.1 10/15/00 www.xicor.com READ OPERATIONS Read operations are initiated in the same manner as write operations with the exception that the R/W bit of the Slave Address Byte is set to one. There are three basic read operations: Current Address Reads, Ran- dom Reads, and Sequential Reads. Current Address Read Internally, the device contains an address counter that maintains the address of the last word read or written incremented by one. After a read operation from the last address in the array, the counter will “roll over” to the first address in the array. After a write operation to the last address in a given page, the counter will “roll over” to the first address on the same page. Upon receipt of the Slave Address Byte with the R/W bit set to one, the device issues an acknowledge and then transmits the eight bits of the Data Byte. The master ter- minates the read operation when it does not respond with an acknowledge during the ninth clock and then issues a stop condition. Refer to Figure 8 for the address, acknowledge, and data transfer sequence. It should be noted that the ninth clock cycle of the read operation is not a “don’t care.” To terminate a read operation, the master must either issue a stop condi- tion during the ninth cycle or hold SDA HIGH during the ninth clock cycle and then issue a stop condition. Figure 8. Current Address Read Sequence Random Read Random read operation allows the master to access any memory location in the array. Prior to issuing the Slave Address Byte with the R/W bit set to one, the master must first perform a “Dummy” write operation. The master issues the start condition and the Slave Address Byte with the R/W bit low, receives an acknowledge, then issues the Word Address Byte 1, receives another acknowledge, then issues the Word Address Byte 0. After the device acknowledges receipt of the Word Address Byte 0, the master issues another start condition and the Slave Address Byte with the R/W bit set to one. This is followed by an acknowledge and then eight bits of data from the device. The master ter- minates the read operation by not responding with an acknowledge and then issuing a stop condition. Refer to Figure 9 for the address, acknowledge, and data transfer sequence. The device will perform a similar operation called “Set Current Address” if a stop is issued instead of the sec- ond start shown in Figure 9. The device will go into standby mode after the stop and all bus activity will be ignored until a start is detected. The effect of this oper- ation is that the new address is loaded into the address counter, but no data is output by the device. The next Current Address Read operation will read from the newly loaded address. Sequential Read Sequential reads can be initiated as either a current address read or random read. The first Data Byte is transmitted as with the other modes; however, the master now responds with an acknowledge, indicating it requires additional data. The device continues to out- put data for each acknowledge received. The master ter- minates the read operation by not responding with an acknowledge and then issuing a stop condition. The data output is sequential, with the data from address n followed by the data from address n + 1. The address counter for read operations increments through all byte addresses, allowing the entire memory contents to be read during one operation. At the end of the address space the counter “rolls over” to address 0000h and the device continues to output data for each acknowledge received. Refer to Figure 10 for the acknowledge and data transfer sequence. the Slave S T A R T Slave Address S T O P A C K Data Signals from the Master SDA Bus Signals from 1 SP 01 0 1 0 S1S0 |
Similar Part No. - X24257B-2.5 |
|
Similar Description - X24257B-2.5 |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.NET |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | 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
