MT25EW Bookham Technology, MT25EW Datasheet - Page 10

• Manufacturer Part Number: MT25EW
• Description: 2.5 Gb/s Transmitter Module - Dwdm, 50 & 100GHz
• Manufacturer: Bookham Technology

www.bookham.com
www.bookham.com
Receiving Data
To receive data from the module e.g. submount temperature, first the module is addressed for write
(R/W bit clear) and the appropriate command is sent. After the module has returned an ACK, a re-start
condition is asserted, and the module is re-addressed for read (R/W bit set). The master can clock out
the appropriate number of bytes from the module. The master must ACK the module for every byte
received, apart from the last byte which the master must NACK. It is very important that the master
sends NACK for the last byte, failure to do so can result in being unable to assert the stop condition if a
low value has been set on the SDA line by the module.
Receiving one byte
Receiving multiple bytes
Command Set Details
CHN (00h)
Sets or return the current operating state. The command either accepts a one byte
operand (unsigned) to set the output state or returns one byte on a read operation.
Valid operands are:
DEF (01h)
Set or return the default power-on state of the module. The command either accepts
a one byte operand (unsigned) to set the channel or returns one byte on a read operation.
Valid channels are:
TUN (02h)
Set or return the optical wavelength fine tune value. This command accepts a one byte
signed operand in the range -80 to +80 (two’s complement). This will give an adjustment
range of approximately 30 pm either side of the ITU grid wavelength. This value is volatile
and is defaulted to zero on power up.
TWL (03h)
Return the ITU grid wavelength in pm. Result is returned as an unsigned 32-bit value,
the MSB is returned first followed by the three lower bytes. The number returned is only
a guide to the nominal wavelength of the currently selected channel and does not change
if e.g. the TUN command is used to shift the frequency. Command is read-only.
LAS (04h)
Return the laser bias current in mA. Result is returned as an unsigned 16-bit value,
MSB first followed by the LSB. Command is read-only.
START ADDRESS (R/W = 0)
START ADDRESS (R/W = 0)
00h - Module disabled
01h - Module enabled
00h - Module disabled at power-on
01h - Module enabled as power-on
ACK
ACK
Slv
Slv
COMMAND
COMMAND
ACK
ACK
Slv
Slv
START ADDRESS (R/W= 1)
START ADDRESS (R/W= 1)
ACK
ACK
Mst
Slv
Thinking optical solutions
Thinking optical solutions
DATA
DATA
NACK
ACK
Mst
Mst
DATA
STOP
NACK
Mst
STOP