AT7908E
Operational Mode 1
This operational mode is selected with mode pin = 1.
This interface operational mode is used to write the AT7908E registers and to readout
from the AT7908E with two different 8-bit data and address buses. The ALE input pin is
not used and the internal registers are mapped between 00Hex and 4C Hex. The Addr
bus will be used as the 8 bits address for the internal registers. To write data on the
internal registers, the MCU must control the CS, WR and RD signals of the AT7908E
and must drive the addr and data buses. The signal WR must be low for, at least, 3
clock cycles. The data is latched at the rising edge of the clock when CS = 1, WR = 0
and RD = 1. The fig. 7 shows the write cycle in the operational mode 1.
Figure 7. Mode 1 Write Cycle
MODE
DATA
Data
LOW ADDRESS
Addr
CS
Clock
WR
Data write
Fig. 8 shows a read cycle. To readout the data from the AT7908E internal registers, the
MCU must drive CS=1, RD=0, WR=1.
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4268D–AERO–11/09
ATMEL [ ATMEL ]
