Datenblatt-Suchmaschine für elektronische Bauteile |
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X1243S8 Datenblatt(PDF) 10 Page - Intersil Corporation |
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X1243S8 Datenblatt(HTML) 10 Page - Intersil Corporation |
10 / 17 page 10 FN8249.0 April 28, 2005 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. 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 rst perform a “dummy” write operation. The master issues the start condition and the Slave Address Byte, receives an acknowledge, then issues the Word Address Bytes. After acknowledging receipts of the Word Address Bytes, the master immediately issues another start condition and the Slave Address Byte with the R/W bit set to one. This is followed by an acknowledge from the device and then by the eight bit word. The master terminates the read operation by not responding with an acknowledge and then issuing a stop condition. Refer to Figure 11 for the address, acknowledge, and data transfer sequence. In a similar operation, called “Set Current Address,” the device sets the address if a stop is issued instead of the second start shown in Figure 11. The X1243 then goes into standby mode after the stop and all bus activity will be ignored until a start is detected. This operation loads the new address into the address counter. The next Cur-rent Address Read operation will read from the newly loaded address. This operation could be useful if the master knows the next address it needs to read, but is not ready for the data. Sequential Read Sequential reads can be initiated as either a current address read or random address read. The rst Data Byte is transmitted as with the other modes; however, the master now responds with an acknowledge, indicat-ing it requires additional data. The device continues to output data for each acknowledge received. The master terminates 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 page and column addresses, allowing the entire memory contents to be serially read during one operation. At the end of the address space the counter “rolls over” to the start of the address space and the device continues to output data for each acknowledge received. Refer to Figure 12 for the acknowledge and data transfer sequence. S t a r t S t o p Slave Address Data A C K SDA Bus Signals from the Slave Signals from the Master 1 1 1 1 1 FIGURE 10. CURRENT ADDRESS READ SEQUENCE 1 Slave Address Word Address 1 S t a r t S t o p Slave Address Data A C K S t a r t SDA Bus Signals from the Slave Signals from the Master Word Address 0 1 1 1 1 0 0 0 00 1 1 11 1 A C K A C K A C K FIGURE 11. RANDOM ADDRESS READ X1243 |
Ähnliche Teilenummer - X1243S8 |
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Ähnliche Beschreibung - X1243S8 |
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