HDNS-2200 View Datasheet(PDF) - Agilent Technologies, Inc
Part Name
Description
MFG CO.
'HDNS-2200' PDF : 36 Pages View PDF
The falling edge of SCLK for the
first address bit of either the read
or write command must be at
least 120 ns after the last SCLK
rising edge of the last data bit of
the previous read operation.
SCLK
Data
PD
> 1 µs
Figure 33. Timing between SCLK and
PD rising edge.
Error Detection and Recovery
1. The ADNS-2030 and the
microcontroller might get out
of synchronization due to ESD
events, power supply droops or
microcontroller firmware
flaws. In such a case the
microcontroller should raise
PD for 100 µs. The ADNS-2030
will reset the serial port but
will not reset the registers, and
be prepared for the beginning
of a new transmission.
2. The ADNS-2030 has a transac-
tion timer for the serial port. If
the 16th SCLK rising edge is
spaced more than approxi-
mately 0.9 seconds from the
first SCLK edge of the current
transaction, the serial port
will reset.
3. Invalid addresses:
Writing to an invalid address
will have no effect. Reading
from an invalid address will
return all zeros.
4. Collision detection on SDIO:
The only time that the
ADNS-2030 drives the SDIO
line is during a READ opera-
tion. To avoid data collisions,
the microcontroller should
relinquish SDIO before the
falling edge of SCLK after the
last address bit. The
ADNS-2030 begins to drive
SDIO after the next rising edge
of SCLK. The ADNS-2030
relinquishes SDIO within
120 ns of the falling SCLK edge
after the last data bit. The
microcontroller can begin
driving SDIO any time after
that. In order to maintain low
power consumption in normal
operation or when the PD pin
is pulled high, the micro-
controller should not leave
SDIO floating until the next
transmission (although that
will not cause any communica-
tion difficulties).
5. In case of synchronization
failure, both the ADNS-2030
and the microcontroller may
drive SDIO. The ADNS-2030
can withstand 30 mA of short
circuit current and will
withstand infinite duration
short circuit conditions.
6. Termination of a transmission
by the microcontroller may
sometimes be required (for
example, due to a USB
suspend interrupt during a
read operation). To accomplish
this the microcontroller should
raise PD. The ADNS-2030 will
not write to any register and
will reset the serial port
(but nothing else) and be
prepared for the beginning of
future transmissions after PD
goes low.
7. The microcontroller can verify
success of write operations by
issuing a read command to the
same address and comparing
written data to read data.
8. The microcontroller can verify
the synchronization of the
serial port by periodically
reading the product ID register.
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