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CAT5409 Fiches technique(PDF) 7 Page - Catalyst Semiconductor |
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CAT5409 Fiches technique(HTML) 7 Page - Catalyst Semiconductor |
7 / 17 page 7 CAT5409 Document No. 2010, Rev. I WRITE OPERATIONS In the Write mode, the Master device sends the START condition and the slave address information to the Slave device. After the Slave generates an acknowledge, the Master sends the instruction byte that defines the requested operation of CAT5409. The instruction byte consist of a four-bit opcode followed by two register selection bits and two pot selection bits. After receiving another acknowledge from the Slave, the Master device transmits the data to be written into the selected register. The CAT5409 acknowledges once more and the Master generates the STOP condition, at which time if a non- volatile data register is being selected, the device begins an internal programming cycle to non-volatile memory. While this internal cycle is in progress, the device will not respond to any request from the Master device. Acknowledge Polling The disabling of the inputs can be used to take advantage of the typical write cycle time. Once the stop condition is issued to indicate the end of the host's write operation, the CAT5409 initiates the internal write cycle. ACK polling can be initiated immediately. This involves issuing the start condition followed by the slave address. If the CAT5409 is still busy with the write operation, no ACK will be returned. If the CAT5409 has completed the write operation, an ACK will be returned and the host can then proceed with the next instruction operation. WRITE PROTECTION The Write Protection feature allows the user to protect against inadvertent programming of the non-volatile data registers. If the WP pin is tied to LOW, the data registers are protected and become read only. Similarly, the WP pin going low after start but after start will interrupt non-volatile write to data registers, while the WP pin going low after internal write cycle has started, will have no effect on any write operation. The CAT5409 will accept both slave addresses and instructions, but the data registers are protected from programming by the device’s failure to send an acknowledge after data is received. Figure 6. Write Timing Figure 5. Slave Address Bits 0 1 0 1 A3 A2 A1 A0 CAT5409 * A0, A1, A2 and A3 correspond to pin A0, A1, A2 and A3 of the device. ** A0, A1, A2 and A3 must compare to its corresponding hard wired input pins. S A C K A C K DR1 WCR DATA S T O P P BUS ACTIVITY: MASTER SDA LINE S T A R T A C K SLAVE/DPP ADDRESS INSTRUCTION BYTE Fixed Variable op code Data Register Address Pot/WCR Address |
Numéro de pièce similaire - CAT5409 |
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Description similaire - CAT5409 |
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