Echelon FTXL Hardware - Manual (Page 83)

FTXL Hardware Guide 75
The figure also shows the status being read after the token is passed.
Read Status
(Ready)
Write
Length 0
Read Status (Busy)
Read
Status:
Ready
Write Token
Read Status
(Busy)
Figure 31. Passing the Token from the Host to the FTXL Transceiver
Figure 32 on page 76 shows the state of the signals while reading a null token
from the FTXL Transceiver. In this figure, the host reads the status three times.
The first two times the status is busy, which indicates that the transceiver has no
data to be read. On the third attempt, the status is ready (D0 is low). Then, the
host reads the data by deasserting A0 while asserting CS~ and R/W~. The data
to be read is in D0-D7, and represents the length of the packet. In this case, the
length is 0x00, and the host now has the token.