ST10R272L - SYNCHRONOUS SERIAL PORT
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command followed by an address, and then the data byte at this address is returned to the
master.
However, if the chip enable line is not deactivated after the EEPROM has transferred the first
data byte, the EEPROM automatically increments to the next address location. If now
subsequent clock pulses are applied to the device, the content of this next location is
transferred to the master, and so on. In this mode, the EEPROM can be continuously read
without having to issue the read command and the start address again.
A similar operation is true for writing to such an EEPROM. These devices allow a certain
number of data bytes to be written after an initial write command followed by a start address
for the writes.
The figure below shows the write operation in continuous mode. The TB0_Full flag is again
used to start subsequent writes to the slave device. The gap between the transfers is
application dependent, since the CPU first has to react on the interrupt request at the end of
one transfer and rewrite the transmit buffer registers before the next transfer will start. This
procedure continues until the mode is switched from continuous mode to normal mode. The
chip enable line will then be deactivated immediately if no transfer is in progress or after the
current transfer is completed.
The following figure shows the read operation in continuous mode. Note that the diagram
shown starts at the point where the master has written the initial information to the slave and
switches the data line SSPDAT from output to input. At the end of a transfer, the byte
Figure 103 Write operation waveforms in continuous mode
SSPCLK
SSPDAT
SSPCE0, 1
TB0
Full
SSP
Interrupt
23,
15,7
22,
14,6
Data driven
to Slave
Data driven
to Slave
0
0
23,
15,7
22,
14,6
23,
15,7
22,
14,6
0
Data driven
to Slave
Disable
Continous
Mode
Write
TBO
Write
TBO
Write
TBO
Service
Interrupt
Service
Interrupt
Service
Interrupt
VR02084A