Rainbow Electronics AT88SA100S - Manual (Page 9)

AT88SA100S [ Preliminary]
9
8558A–SMEM–03/09
3.1.2. Transmit Flag
The transmit flag is used to turn around the signal so that the device can send data back to the system, depending on
its current state. The bytes that the device returns to the system, depending on its current state as follows:
Table 6. Return Codes
State Description Error/Status Description
After wake, but prior to first
command 0x11 Indication that a proper wake token has been received by the device.
After successful command
execution
–
Return bytes per “Output Parameters” in Command section of this
document. In some cases this is a single byte with a value of 0x00
indicating success. The transmit flag can be resent to the device
repeatedly if a re-read of the output is necessary.
Execution error 0x0F Command was properly received but could not be executed by the
AT88SA100S chip. Changes in the AT88SA100S chip state or the
value of the command bits must happen before it is re-attempted.
After CRC or other parsing
error 0xFF Command was NOT properly received by the device and should be
re-issued by the system.
The device always transmits complete blocks to the system, so in the above table the status/error bytes result in 4
bytes going to the system – count, error, CRC x 2.
After receipt of a command block, the device will parse the command for errors, a process which takes t
PARSE
(Refer to 3.1.1 ). After this interval the system can send a transmit token to the device – if there was an error then the
device will respond with an error code. If there is no error then the device internally transitions automatically from t
PARSE
to t
EXEC
and will not respond to any transmit tokens until both delays are complete.
3.1.3. Sleep Flag
The sleep flag is used to transition the device to the low power state, which causes a complete reset of the device’s
internal command engine and input/output buffer. It can be sent to the device at any time when the device will accept a
flag.
To achieve the specified I
SLEEP
Atmel recommends that the input signal be brought below V
IL
when the chip is asleep. To
achieve I
SLEEP
if the sleep state of the input pin is high, the voltage on the input signal should be within 0.5V of V
CC
to
avoid additional leakage on the input circuit of the chip.
3.1.4. Pause State
The pause state is entered via the PauseLong command and can be exited only when the watchdog timer has expired
and the chip transitions to a sleep state. When in the pause state, the chip ignores all transitions on the signal pin but
does not enter a low power consumption mode.
The pause state provides a mechanism for multiple AT88SA100S chips on the same wire to be selected and to
exchange data with the host microprocessor. The PauseLong command includes an optional address field which is
compared to the values in Fuses 84-87. If the two match, then the chip enters the pause state, otherwise it continues to
monitor the bus for subsequent commands. The host would selectively put all but one AT88SA100S in the pause state
before executing the MAC command on the active chip. After the end of the watchdog interval all the chips will have
entered the sleep state and the selection process can be started with a wake token (which will then be honored by all
chips) and selection of a subsequent chip.