AS3517H-ECTP datasheet(31/94 Pages) AMSCO

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AS3517 V17

Data Sheet, Confidential

www.austriamicrosystems.com

Figure 14 Random Read

Random Read and Sequential Read are combined formats. The repeated START condition is used to change the direction after the data

transfer from the master.

The word address transfer is initiated with a START condition issued by the master while the bus is idle. The START condition is followed

by the device-write address and the word address.

In order to change the data direction a repeated START condition is issued on the 1st SCL pulse after the acknowledge bit of the word

address transfer. After the reception of the device-read address, the slave becomes the transmitter. In this state the slave transmits

register data located by the previous received word address vector. The master responds to the data byte with a not-acknowledge, and

issues a STOP condition on the bus.

Figure 15 Sequential Read

Sequential Read is the extended form of Random Read, as more than one register-data bytes are transferred subsequently. In difference

to the Random Read, for a sequential read the transferred register-data bytes are responded by an acknowledge from the master. The

number of data bytes transferred in one sequence is unlimited (consider the behaviour of the word-address counter). To terminate the

transmission the master has to send a not-acknowledge following the last data byte and generate the STOP condition subsequently.

Figure 16 Current Address Read

To keep the access time as small as possible, this format allows a read access without the word address transfer in advance to the data

transfer. The bus is idle and the master issues a START condition followed by the Device-Read address. Analogous to Random Read, a

single byte transfer is terminated with a not-acknowledge after the 1st register byte. Analogous to Sequential Read an unlimited number of

data bytes can be transferred, where the data bytes has to be responded with an acknowledge from the master. For termination of the

transmission the master sends a not-acknowledge following the last data byte and a subsequent STOP condition.

Revision 1v3

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