Rainbow Electronics 71M6542G - Manual (Page 71)

v1.1 © 2008–2011 Teridian Semiconductor Corporation 71
Table 60: EECTRL Bits for 2-pin Interface
Status
Bit
Name
Read/
Write
Reset
State
Polarity Description
7 ERROR R 0 Positive 1 when an illegal command is received.
6 BUSY R 0 Positive 1 when serial data bus is busy.
5 RX_ACK R 1 Positive 1 indicates that the EEPROM sent an ACK bit.
4 TX_ACK R 1 Positive
1 indicates that an ACK bit has been sent to the
EEPROM.
3:0 CMD[3:0] W 0000 Positive
CMD[3:0] Operation
0000 No-op command.
0010 Receive a byte from the EEPROM
and send ACK.
0011 Transmit a byte to the EEPROM.
0101 Issue a STOP sequence.
0110 Receive the last byte from the
EEPROM and do not send ACK.
1001 Issue a START sequence.
Others No operation, set the ERROR bit.
The EEPROM interface can also be operated by controlling the DIO2 and DIO3 pins directly. The
direction of the DIO line can be changed from input to output and an output value can be written
with a single write operation, thus avoiding collisions (see
Table 15 Port Registers (SEGDIO0-15)).
Therefore, no resistor is required in series SDATA to protect against collisions.
2.5.9.2 Three-wire (µ-Wire) EEPROM Interface with Single Data Pin
A 500 kHz three-wire interface, using SDATA, SDCK, and a DIO pin for CS is available. The interface is
selected by setting DIO_EEX[1:0] = 10. The EECTRL bits when the three-wire interface is selected are
shown in
Table 61 . When EECTRL is written, up to 8 bits from EEDATA are either written to the EEPROM
or read from the EEPROM, depending on the values of the EECTRL bits.
2.5.9.3 Three-wire (µ-Wire/SPI) EEPROM Interface with Separate Di/DO Pins
If DIO_EEX[1:0]=11, the three-wire interface is the same as above, except DI and DO are separate pins.
In this case, SEGDIO3 becomes DO and SEGDIO8 becomes DI. The timing diagrams are the same as
for DIO_EEX[1:0]=10 except that all output data appears on DO and all input data is expected on DI. In
this mode, DI is ignored while data is being received on DO. This mode is compatible with SPI modes 0,0
and 1,1 where data is shifted out on the falling edge of the clock and is strobed in on the rising edge of
the clock.
Table 61: EECTRL Bits for the 3-wire Interface
Control
Bit
Name
Read/
Write
Description
7 WFR W
Wait for Ready. If this bit is set, the trailing edge of BUSY is delayed until
a rising edge is seen on the data line. This bit can be used during the
last byte of a Write command to cause the INT5 interrupt to occur when
the EEPROM has finished its internal write sequence. This bit is ignored
if Hi-Z=0.
6 BUSY R
Asserted while the serial data bus is busy. When the BUSY bit falls, an
INT5 interrupt occurs.
5 HiZ W
Indicates that the SD signal is to be floated to high impedance immediately
after the last SDCK rising edge.