STMICROELECTRONICS VT5376V032

VT5376
Ultra-low power laser motion sensor for laser mouse applications
Preliminary Data
Features
■
Ultra-low power performance and high
speed/high accuracy motion detection
(1 m/s, 20 g)
■
Optional on-chip power management scheme
(RUN/IDLE1/IDLE2/SLEEP)
■
On-chip boost-converter controller enables a
complete autonomous single AA/AAA-type
battery supply application
■
■
Figure 1.
AVDD DVDD VREG VBat
■
CPI programmable up to 3200 CPI
■
On-chip ADC for battery level reporting
■
Laser drive circuitry, fault detection scheme
and safety features
■
Versatile usage: the sensor is designed to
operate with a companion microcontroller, and
can be used for any laser/LED mouse system
although it is optimized for wireless
applications (27 MHz/2.4 GHz/BT).
■
RoHS (lead-free) package
VREF
VGATE Start
VGATE On
VTOP
VT5376
RBIN
RC_OSC
I2C interface, with fast polling rate capability for
high end applications
(report rate up to 1 per ms)
Internal oscillator
VTOP
(>=2.2V)
Single battery
Very low quiescent and operating current mode
for battery life saving
■
Application block diagram
Laser Out
ResetOut
SDA
SCL
Power Down
Motion
Laser NEN
Vtop
Vtop
MCU
RF module
/ USB
Buttons
Scroll Wheel
Tilt Wheel
Applications
■
Ultra-low power wireless laser mouse,
27 MHz, 2.4 GHz and Bluetooth
■
Also suitable for laser USB mouse applications
Description
This device is intended to fit into any 2-chip
applications (companion MCU) and offers the
best compromise between application cost,
power and performance.
September 2008
Rev 2
This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to
change without notice.
1/30
www.st.com
30
Contents
VT5376
Contents
1
2
3
4
Motion performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1
Technical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2
Battery life management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.1
Manual power management via POWERDOWN pin . . . . . . . . . . . . . . . . 4
1.2.2
Automatic power management via internal timer . . . . . . . . . . . . . . . . . . . 5
Power supply options and power consumption . . . . . . . . . . . . . . . . . . . 7
2.1
Low cost application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2
External supply application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1
Supply voltages (using internal DC/DC controller) . . . . . . . . . . . . . . . . . . . 8
3.2
Supply voltages (direct drive, bypassing DC/DC controller) . . . . . . . . . . . . 8
3.3
Logic IO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1
Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2
Data format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.3
Message interpretation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.4
Type of messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5
I2C control register map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6
Laser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7
2/30
6.1
Direct laser drive and calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.2
Laser or led system managed by host (external micro) . . . . . . . . . . . . . . 18
6.3
Laser fault detection and safety feature . . . . . . . . . . . . . . . . . . . . . . . . . . 18
General features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.1
Device clocking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.2
Battery level monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.3
Resolution setting (counts/inch) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.4
Image (frame) capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
VT5376
8
Contents
7.5
Image streaming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7.6
Optical centre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.7
Sensor orientation on PCB (with lens) . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
8.1
9
Pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
9.1
10
Overall 2.4 GHz mouse power consumption example . . . . . . . . . . . . . . . 24
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
10.1
TQFP package guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
11
Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
12
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3/30
Motion performance
1
VT5376
Motion performance
The sensor can operate with a VCSEL or LED (visible and IR), and when bundled with the
appropriate optics subsystem is able to track motion on a wide range of surfaces up to
speeds of 1 m/s (40 ips), and to detect acceleration of up to 20 g. The sensor achieves this
top speed with very low drift and high accuracy.
Note:
Although this device features an UltraLowPower motion detection machine, the power
saving has not been achieved by compromising tracking accuracy.
1.1
Technical specifications
Table 1.
Technical specifications
Parameter
Description
Resolution
Programmable up to 3200 CPI
Pixel size
30.4µm
Array size
20*20 pixels
Frame rate
up to 4000 fps
Tracking performances
Laser or LED: 1m/s
Very low drift.
Supply voltage
1 V to 1.6 V (1)
Operating temperature
0°C to 60°C
Package type
7 mm x 7 mm x 1.4 mm 32 lead LOQFP
(Low profile Optical Quad Flat Pack)
1. Using internal boost converter controller. Otherwise, voltage supply ranges from 1.7V to 1.9V.
1.2
Battery life management
The battery life management (in no motion state) can be done manually where the external
MCU is the master and controls the sensor state via its POWERDOWN pin (default mode).
Alternatively, the sensor can manage its own power states. In no motion, it cycles through
IDLE and SLEEP modes automatically without any intervention from the MCU.
Therefore by using the sensor’s automatic power management, the MCU can be fully
switched OFF in the case of no motion allowing for extra power savings, and resulting in a
very simple driver firmware design.
1.2.1
Manual power management via POWERDOWN pin
In this mode the chip is woken-up by de-asserting the POWERDOWN pin. When doing so
both the analog and DCDC engines are woken up in a programmed sequence. The
POWERDOWN pin can be re-asserted straight away as the sensor undergoes just a single
frame sequence.
4/30
VT5376
Motion performance
1.2.2
Automatic power management via internal timer
In this mode, after having written the initialization I2C command, the POWERDOWN pin
must be left high at all times.
In running mode the motion engine operation is basically the same as the manual power
management mode, however, in the case of no motion (after a set time) the chip now has
the ability to put itself to sleep for a determined period of time. This mode features the usual
modes: RUNNING, IDLE1, IDLE2 and SLEEP, with on-chip preprogrammed time constants
(firmware).
If no motion is detected the VT5376 will in turn cycle to IDLE1/IDLE2 then SLEEP. In each of
these modes, the behavior is a single frame operation; the RC timer is programmed to wake
up for the next period then the sensor goes to sleep. The MOTION pin will go high if motion
is detected. The sensor will remain in RUN mode until the host has polled ALL motion data.
In this automatic power management mode the external MCU can set itself to STDBY and
just wait for the MOTION pin to come up, hence saving power in the no motion condition.
This enables the application MCU firmware to be simplified as much as possible.
Figure 2.
Automatic power management
System is up and running (3 sub m odes):
- low fram e rate (1K fps) for m otion slower than 4ips
- m edium fram e rate (2Kfps) for m otion betw een 4 and 8ips
- fast fram e rate (4K fps) for m otion faster than 8ips
RUN MODE
N o m otion for 50m s
M otion detected
System w akes for
1 fram e every 10m s
to check for m otion
S LE E P M O D E
ID LE 1 M O D E
After 8 secs of ID LE 1 m ode
System w akes for
1 fram e every 500m s
to check for m otion
After 10 m ins of ID LE 2 m ode
ID LE 2 M O D E
System wakes for
1 fram e every 100m s
to check for m otion
The VT5376 automatic power management has a four state power scheme; RUN, IDLE1,
IDLE2 and SLEEP.
RUN mode is the mode where the whole system is up and running. This mode has three
sub-modes, dependant on the mouse velocity: 1K fps (for motion slower than 4 ips), 2K fps
(for motion between 4 ips and 8 ips) and 4K fps (for motion faster than 8 ips). As long as
there is motion the mouse will remain in this state.
After 50 ms of mouse inactivity the mouse goes into the IDLE 1 mode. In this mode, the
system wakes up every 10 ms for 1 frame and checks for motion; if the mouse has not
moved the system automatically goes back to its low power state otherwise the system will
go into RUN mode.
After 8 seconds of IDLE 1 mode, the system then goes into IDLE 2 mode where it wakes up
for 1 frame every 100 ms. After 10 minutes of no activity the system falls into SLEEP mode,
5/30
Motion performance
VT5376
which is exactly the same as the IDLE modes except that the system wakes up only every
500 ms to check motion activity.
6/30
VT5376
Power supply options and power consumption
2
Power supply options and power consumption
The sensor includes a DCDC controller to supply the laser / LED. This allows the overall
sensor system to operate from a single AA or AAA battery supply voltage (from 1.6V down
to 1V), allowing for a simple and low power / low cost system design. Two power supply
schemes can be used.
2.1
Low cost application
The internal DCDC controller and voltage regulators are used so that the overall application
can be supplied from a single AA/AAA battery cell, without the need for an external step-up
convertor device. This approach is extremely economical.
Table 2.
Typical power supply and power consumption
Run
IDLE1
IDLE2
SLEEP
2.4 mA
0.3 mA
0.15 mA
0.1 mA
0.04 mA
0.04 mA
0.04 mA
0.04 mA
4000 fps
2000 fps
1000 fps
Total @ ITop
(chip + Laser/LED)
5.8 mA
3.5 mA
Total chip @Vbat
0.04 mA
0.04 mA
Note:
2.2
1
DCDC efficiency from single battery cell to Vtop (typical 2.2V) is around 70%.
2
Maximum load on Vtop is 25mA
External supply application
In this instance, the internal DCDC controller and voltage regulators are turned off and
bypassed. The sensor then needs to be supplied with a single regulated 1.8V +/- 0.1V.
Table 3.
Power supply and typical power consumption
Run
Total
@Vtop/Vbat/Dvdd/
Avdd (1.8V)
Chip + Laser/LED
4000 fps
2000 fps
1000 fps
5.8 mA
3.5 mA
2.4 mA
IDLE1
IDLE2
SLEEP
0.3 mA
0.15 mA
0.1 mA
7/30
Electrical characteristics
VT5376
3
Electrical characteristics
3.1
Supply voltages (using internal DC/DC controller)
Table 4.
Supply voltages using DC/DC controller
Symbol
Parameter
Min.
Typ.
Max.
Unit
VTOP
Boosted
supply(1)
2.0
2.2
2.6
V
VBAT
Supply from single AA cell
1.0
1.25
1.6
V
1. Value defined by resistors ratio
3.2
Supply voltages (direct drive, bypassing DC/DC controller)
Table 5.
Supply voltage values (direct drive, bypassing DC/DC controller)
Symbol
3.3
Parameter
Min.
Typ.
Max.
Unit
VTOP
Boosted supply
1.7
1.8
1.9
V
VBAT
Supply from single AA cell
1.0
1.8
1.9
V
AVDD
Analog supply
1.7
1.8
1.9
V
DVDD
Digital core supply
1.7
1.8
1.9
V
VREG
Digital core supply
1.7
1.8
1.9
V
Min.
Typ.
Max.
Unit
Logic IO
Table 6.
Digital IO electrical characteristics
Symbol
Parameter
CMOS digital inputs (Reset_Out, Motion, PowerDown, SDA and SCL)
VIL
Low level input voltage
0
0.3*VDD
V
VIH
High level input voltage
0.7*VDD
VDD + 0.3
V
IIL
Low level input current
-1
µA
IIH
High level input current
1
µA
0.3*VDD
V
CMOS digital outputs
8/30
VOL
Low level output voltage (4mA load)
VOH
High level output voltage (4mA load)
0.7*VDD
V
VT5376
4
Interface
Interface
The interface is 400 kHz I2C, with very fast polling rate for high CPI applications (down to
1 ms period).
4.1
Protocol
Figure 3.
Serial interface data transfer protocol
Acknowledge
Start condition
SDA
MSB
SCL
S
1
LSB
2
3
4
5
P
8
7
6
A
Address or data byte
Stop condition
4.2
Data format
Information is packed in 8-bit packets (bytes) always followed by an acknowledge bit. The
internal data is produced by sampling sda at a rising edge of scl. The external data must be
stable during the high period of scl. The exceptions to this are start (S) or stop (P) conditions
when sda falls or rises respectively, while scl is high.
The first byte contains the device address byte which includes the data direction read, (r),
~write, (~w), bit.
Figure 4.
VT5376 serial interface address
0
0
1
0
0
0
0
R/W
The byte following the address byte contains the address of the first data byte (also referred
to as the index).
9/30
Interface
4.3
VT5376
Message interpretation
All serial interface communications with the sensor must begin with a start condition. If the
start condition is followed by a valid address byte then further communications can take
place. The sensor will acknowledge the receipt of a valid address by driving the sda wire
low. The state of the read/~write bit (lsb of the address byte) is stored and the next byte of
data, sampled from sda, can be interpreted.
During a write sequence the second byte received is an address index and is used to point
to one of the internal registers. The serial interface will automatically increment the index
address by one location after each slave acknowledge. The master can therefore send data
bytes continuously to the slave until the slave fails to provide an acknowledge or the master
terminates the write communication with a stop condition or sends a repeated start, (Sr).
As data is received by the slave it is written bit by bit to a serial/parallel register. After each
data byte has been received by the slave, an acknowledge is generated, the data is then
stored in the internal register addressed by the current index.
During a read message, the content of the addressed register is then parallel loaded into the
serial/parallel register and clocked out of the device by scl.
At the end of each byte, in both read and write message sequences, an acknowledge is
issued by the receiving device. A message can only be terminated by the bus master, either
by issuing a stop condition, a repeated start condition or by a negative acknowledge (NAck)
after reading a complete byte during a read operation.
4.4
Type of messages
Single location, single data write
When a random value is written to the sensor, the message will look like this:
Figure 5.
Single location, single write
Device
address
Start
S
20h
Ack
Index
A
07h
Stop
Data
A
00h
A
P
The r/w bit is set to zero for writing. The write message is terminated with a stop condition
from the master.
Single location read
When a location is to be read, but the value of the stored index is not known, a write
message with no data byte must be written first, specifying the index. The read message
then completes the message sequence. To avoid relinquishing the serial to bus to another
master a repeated start condition is asserted between the write and read messages.
10/30
VT5376
Interface
Figure 6.
Single read
No data write
S
20h
A
Read data
20h
A Sr
21h
A
15
A
P
NAck
from the master
As mentioned in the previous example, the read message is terminated with a negative
acknowledge (A) from the master.
Multiple location write
It is possible to write data bytes to consecutive adjacent internal registers without having to
send explicit indexes prior to sending each data byte.
Note:
An auto-increment write is assumed if no stop condition occurs.
Figure 7.
Multiple location write
Incremental write
S
20h
A
07h
A
11
A
data written
@ index = 07
C1
A
P
data written
@ index = 08
Multiple location read: reading motion value example
Multiple locations can be read within a single read message. An auto-increment write is
assumed.
Note:
Registers are read until the master Nacks the data.
Figure 8.
Multiple location read: reading motion
No data write
S
20h
A
21h
Incremental read
A Sr
21h
A
Xmotion
A
Ymotion
A P
11/30
I2C control register map
VT5376
5
I2C control register map
Table 7.
I2C control register map
Address
Bits
0x00
[7:0]
0x01
[7:0]
[0]
[1]
Name
R/W
Default
Device Hardware revision
RO
00h
HW revision: set by the mask set
revision
Device Soft revision
RW
01h
FW revision: is updated every time
internal firmware of minor revision is
done.
0h
When set, the device controls its own
power mode state machine in no
motion condition. If not set,
POWERDOWN controls the state of
the device (standby/run)
0h
When set, the device sets all internal
variables to optimize the system for
laser illumination.
If set, LASER_OUT is actived to direct
drive a VCSEL, and LASER_NEN
controls its power supply switch.
If not set, LASER_NEN becomes the
LED_ON signal, toggling at frame
rate.
0h
1: The device switches its internal
1.8 V regulator off, and assumes 1.8 V
will be supplied at all times to Vtop,
DVDD and AVDD. VBat can also be
supplied by the same 1.8V or from a
single battery.
0: Device uses internal regulators
(Vtop must be set >= 2.2V).
Automatic Power management
Laser Selected
RW
RW
0x05
[2]
12/30
Use External Supply
RW
Description
[3]
Host Config Done
RW
0h
This bit must be set to 1 to indicate to
the chip that the boot configuration of
the sensor (mainly this register) is
complete, and it can start motioning.
[5]
Led dac driven
RW
0h
If set to 1, and the chip is set in LED
mode, then the LED is direct driven by
the internal DAC.
[7]
fw idle state
RW
0h
If enabled the MCU firmware will go
into an idle mode (I2C commands still
available).
VT5376
Table 7.
Address
I2C control register map
I2C control register map (continued)
Bits
[7]
Name
Force Laser Out ON
R/W
RW
Default
Description
0h
If set to 1, this sets the LASER_OUT
DAC always ON (instead of toggling
normally). This mode is provided in
case the DAC current needs
calibrating. To confirm this mode,
register 0x0D will also need to be
written to (complement data).
Sets DAC current setting. To validate
the setting, register 0x0D will also
need to be written to (complement
data). With Rbin = 12K ohms,
0x7F: 3.4mA
0x00: 10mA.
0x0A
[6:0]
DAC current setting
RW
7Fh
[0]
Laser Drive Enable
RW
0h
0: Current source OFF
1: Enable current source
[1]
Laser NEN Out
RW
1h
Laser NEN pin state
Note: This command is only valid if bit
[5] is 1
1h
0: LASER_NEN 1.8V capable CMOS
1: LASER_NEN - OpenDrain 5V
tolerant
Note: This command is only valid if bit
[5] is 1
[2]
Laser NEN OD Enable
RW
[3]
Force Laser Out High
RW
0h
0: Normal operation, LASEROUT set
by DAC
1: Set to 1 to detect short to GND on
LASER_OUT
[4]
Laser comp Enable
RW
0h
0: Disable fault detection comparators
1: Enable fault detection comparators
0x0B
[5]
Laser NEN trk led n
RW
0h
0: LASER_NEN replaced by
TRK_LED pulse (LED)
1: LASER_NEN controlled by bits [1]
and [2] (Laser)
[6]
Laser Bias Enable
RW
0h
0: Disable bias current source
1: Enable bias current source
Note: valid only if bit [7] is high
0h
0 : Laser bias is driven the same way
as laser drive (DAC)
1 : Laser bias is controlled with
laser_bias_enable signal (bit [6])
[7]
Laser Bias Ctrl
RW
13/30
I2C control register map
Table 7.
Address
I2C control register map (continued)
Bits
[5]
0x0C
VT5376
[6]
[7]
[7]
Name
Rbin Low
Laser Low
Laser High
Force Laser Out ON (Compl)
R/W
RO
RO
RO
RW
Default
0h
0: Rbin above threshold
1: Rbin below threshold (shorted to
GND)
Note: if Laser_Comp_Enable (reg
0x0B, bit [4]) = 0, Rbin_Low=1
0h
0: Laser OUT above LOW threshold
1: Laser OUT below LOW threshold
(shorted to GND).
Note: if Laser_Comp_Enable = 0,
Laser_Low = 1
0h
0: Laser OUT below HIGH threshold
1: Laser OUT above HIGH threshold
(shorted to VDD).
Note: if Laser_Comp_Enable = 0,
Laser_High = 1
1h
If set to 0, this sets the LASER_OUT
DAC always ON (instead of toggling
normally). This mode is provided in
case the DAC current needs
calibrating. To confirm this mode,
register 0x0A will also need to be
written to (complement data).
00h
Sets DAC current setting. To validate
the setting, register 0x0A will also
need to be written to (complement
data). With Rbin = 12K ohms,
0x00: 3.4mA
0x7F: 10mA
0x0D
[6:0]
0x21
0x22
0x23
14/30
DAC current setting (Compl)
RW
Description
RO
This register holds the overall X
movement data since last polling was
done.
Value is 8 bit 2’s complement.(1)
Y_motion
RO
This register holds the overall Y
movement data since last polling was
done.
Value is 8 bit 2’s complement.(1)
[0]
X Overflow
RO
0h
This register records if the X-motion
integrator has reached its limit.
[1]
Y Overflow
RO
0h
This register records if the Y-motion
integrator has reached its limit.
[3]
No Motion
RO
0h
This bit is asserted if both X/Y
integrators are empty
[7:0]
[7:0]
X_motion
VT5376
Table 7.
Address
0x27
I2C control register map
I2C control register map (continued)
Bits
0x2A
R/W
Default
Description
[0]
Invert X
RW
0h
Allows X to be inverted (2)
[1]
Invert Y
RW
0h
Allows Y to be inverted(2)
[3]
Swap XY
RW
1h
Replaces X with Y and Y with X
[5]
Test Pattern Enabled
RW
0h
0: Normal mode
1: Diamond shape pattern
0h
Diamond test pattern speed 0x0 : motion = 127 max speed
0x1 : motion = 64
0x2 : motion = 32
0x3 : motion = 16
[7]
0x29
Name
[7:0]
[7:0]
Test Pattern Speed
Min_features[13:6]
Scaling for X motion vectors
Scaling for Y motion vectors
RW
RW
This register represents the feature
threshold below which motion is no
longer valid (in this case, the device
0000_0100
reports “0” motion). This is linked to
the value reported in registers
0x31/0x32
RW
Sets resolution as CPI:
8: 400 CPI
0001_0000
16: 800 CPI
Assuming lens magnification of x0.5
RW
Sets resolution as CPI:
0x08: 400 CPI
0001_0000
0x10: 800 CPI
Assuming lens magnification of x 0.5
0x2B
[7:0]
0x31
[15:8]
0x32
[7:0]
0x41
[7:0]
Exposure [8:1]
RW
80h
Exposure value in 2 x CLK12 period
units
0x43
[4]
Auto Expo En
RW
1h
Auto exposure enable
RO
Feature count report: the higher the
value, the more distinctive features the
surface requires, for the motion
detection machine to operate reliably.
Features count
0x47
0x4F
[7:0]
[7:0]
RO
Vbat converted data
Exp max value
RO
This register holds the current
converted data from the Vbat input
voltage.
The data range is as follows:
0000_0000: Vbat = 0.6 V
1111_1111: Vbat = 1.6 V
The response is linear for each value
in between. ADC step: 1V/256 =
3.9mV
RO
This registers holds the maximum
pixel value (before CDS) for the
current frame. It shows if some pixels
are saturated or not.
15/30
I2C control register map
Table 7.
Address
0x61
0x62
0x82
VT5376
I2C control register map (continued)
Bits
[7:0]
Name
IMAGE[7:0]
[0]
Frame dump mode enable
[1]
Frame dump start
[2]
Frame ready for download
[3]
Frame upload complete
R/W
Default
Description
RO
This register contains the pixel value
when the frame dump feature has
been activated (reg 0x62, bit 0).
To read the 400 pixels from the
captured frame, the register must be
read 400 consecutive times.
RW
0h
If set to 1, the device will capture a
single frame. When the frame is
captured and ready to be downloaded
via reg 0x61, bit 2 (frame ready) is set.
0h
Bit is set at start of frame dump
0h
This bit is asserted when the captured
frame is ready to be downloaded via
reg 0x61.
When frame download is complete,
bit 3 is reset
0h
This flag is set when all 400 pixels
have been read by I2C host.
RO
[4]
PCI Test enable
R/W
0h
If set Motion, Laser_NEN, Reset_Out
and VGate_On become PCI data
ouptuts (QCLK, FST and 2 bits serial
data)
[1]
Timer ITR enable
R/W
1h
Timer interrupt enable.
1. Internal ACCUMULATOR is reduced from this value every time it is read.
2. Default changes to 1 for a laser system after host_config_done (that is, system set up for optics without a lens)
16/30
VT5376
Laser
6
Laser
6.1
Direct laser drive and calibration
The sensor includes a 7-bit DAC and an output current source.
The DAC value must be set via two I2C commands after power-up (default is MIN = 3.4mA,
with Rbin = 12K).
To allow VCSEL output power measurements to be done, the user can set the laser out
(normally strobed during operation) to continuously on via an I2C command. This feature is
optional and is designed to offer maximum flexibility.
Alternatively, the Idac maximum (up to a max = 13mA) and minimum values can be changed
by adjusting the Rbin value (for example, with Rbin = 24K, Idac max = 5mA and Idac min =
1.7mA).
Idac max is set by the formula:
Idac (max) = 120/Rbin (result in mA, Rbin in kohms)
No external driver is required, just a FET power switch controlled by LASER_NEN signal.
Figure 9.
Application schematics using Laser or LED (driven with internal DAC or external
current source)
Laser system driven by internal DAC
laser_selected = 1
LED system driven by internal DAC LED system driven by external drive
laser_selected = 0
laser_select = 0
led_dac_driven = 1
led_dac_driven = 0
VTOP
VTOP
36X trk_led (active high)
VTOP
LASER_NEN
LASER_NEN
laser
LASER_NEN
LED
LASER_OUT
LASER_OUT
LASER_OUT
RBIN
RBIN
RBIN
VT5376
LED
VT5376
VT5376
17/30
Laser
6.2
VT5376
Laser or led system managed by host (external micro)
The host must first select LED or LASER (bit [1] of register 0x05).
●
LED
The host must select if the LED is to be driven by the internal DAC or an external
current supply using bit [5] of register 0x05 (led_dac_driven). Bit [3] of register 0x05
(host_config_done) then needs to be set.
●
–
Case internal DAC drive: VT5376 sets the maximum current from the DAC and
the system starts running.
–
Case external drive: VT5376 powers down its laser_drive and the led_on signal
is present on the LASER_NEN pin.
LASER
The host must first decide whether to perform LASER fault detection (described in
Section 6.3) then set bit [3] of register 0x05 (host_config_done).
If the system passes the laser fault detection (or laser fault detect was not performed),
the host can then adjust the LASER DAC current by writing a value to bits [0-6] in
register 0x0A AND writing its complementary value to bits [0-6] of register 0x0D, if the
values are not compatible the VT5376 applies the minimum DAC current.
6.3
Laser fault detection and safety feature
The sensor includes a set of diagnostic features that can be carried out at power-up (before
setting host_config_done). The tests listed below can be selected.
●
Check LASER_OUT is not shorted to VDD (LASER_OUT < 1.2V).
–
Enable DAC and disable OUT_HIGH switch by writing 0xF7 to register 0x0B (Top_
laser_setting), then make force_laser_out_on = 1, by writing 0x01 to bit 7 of
register 0x0A (Top_laser_DAC_setting), and 0 to it’s complementary bit (bit 7) in
register 0x0D (Top_laser_Dac_setting_C). Finally read bit 6 of register 0xC to
ensure that laser_low = 1.
External LASER_NEN switch must be fitted in order to make LASER_OUT go
below 0.4V.
●
Check LASER_OUT and RBIN are not shorted to GND (LASER_OUT and
RBIN > 0.4V).
–
Disable DAC and enable OUT_HIGH switch (force_laser_out_high = 1) by writing
0xFE to register 0x0B (Top_laser_setting). Then read register 0x0C
(Top_laser_diagnostics) to ensure that bit 7 (laser_high) is set to 1 and bit 5
(Rbin_low) is set to 0.
If the result of these tests is a pass then the MCU can set the laser system as follows:
18/30
1.
Set bit [3] of register 0x05 (host_config_done).
2.
Write 0x25 (laser_drive and laser_nen enable) in register 0x0B (Top_laser_setting).
3.
Write the required DAC value (bits 0-6) in register 0x0A (Top_laser_DAC_setting)
ensuring that force_laser_out_on = 0. Write the 1’s complement value of the above
setting in register 0x0D (Top_laser_Dac_setting_C).
VT5376
General features
7
General features
7.1
Device clocking
The device integrates its own oscillator. It does not require an external Xtal or resonator,
instead it requires only an external capacitor of 33 pF. The accuracy of this cap will
determine the accuracy of the internal clock. Ignoring the capacitor accuracy, the frequency
will be accurate within 10% range.
7.2
Battery level monitoring
The device includes an 8-bit ADC that translates the VBAT voltage into an 8-bit value that
can be read via I2C. The external MCU can upload this value and take any action required.
7.3
Resolution setting (counts/inch)
Due to an accurate on-chip interpolation process, the device operates below the pixel
resolution. This enables the user to easily select any desired resolution via a simple register
write.
Note:
Different resolutions can be applied to X and Y. This could be useful in case of optical
non-symmetry or distortion.
7.4
Image (frame) capture
It is possible to capture an image and download it using a simple I2C write/read sequence.
This is useful to calibrate optics during pre-production or to perform basic tests.
In order to achieve this, the user must:
1.
Put the firmware into IDLE by setting bit 7 of register 0x05 (fw_idle_state).
2.
Disable the motion engine controller by clearing bit 1 of register 0x82
(timer_itr_enable).
3.
Enable frame dump mode by setting bit 0 of register 0x62
(frame_dump_mode_enable).
The VT5376 resets the sensor, enables the DCDC, runs a single frame sequence and
stores it into an internal RAM. Once this process is complete, the VT5376 signals that the
image is ready for download, by asserting bit 2 in register 0x62
(frame_ready_for_download).
When this flag is asserted, the user can download the 400 consecutive pixels by reading
register 0x61 (image) 400 consecutive times.
When all the pixels have been read, the VT5376 signals the end of the process by setting
bit 3 in register 0x62 (frame_upload_complete).
To resume normal operation the user should reset bit 0 in register 0x62 to exit the frame
dump mode, take the firmware out of Idle by resetting bit 7 of register 0x05 and set bit 1 of
register 0x82 to enable the motion controller.
19/30
General features
VT5376
Figure 10. Frame dump mode timing diagram
400 x I2C single reads of pixel data
set by user
set by 376
set by 376
reset by user
frame_dump_en
frame_dump_ready
frame_dump_pixel
0
1
2
3
398
399
pixel address
frame_dump_completed
NORMAL MODE
7.5
FRAME DUMP MODE
NORMAL MODE
Image streaming
To enter this test mode, set bit 4 of registry 0x62 to 1 (PCI_test_enable).
In this mode, the pins VGATE_ON, RESET_OUT, LASER_NEN and MOTION are used to
output serially fast video data in the form of 2 bits nibble + FST and QCLK.
Upon receipt of an FST (LASER_NEN) rising edge, NIB_EVEN (VGATE_ON) and
NIB_ODD (RESET_OUT) output data every 48 MHz clock cycle. The signals should be
sampled 10 ns after the FST rising edge, and then every 20.8 ns exactly, during
400 x 4 = 1600 cycles.
Groups of four consecutive NIB_EVEN and NIB_ODD must then be repackaged together to
form a single 8-bit pixel data. This format enables the pixels to be output at the same frame
rate as normal operation, and keeps I2C available to access the usual register settings.
For more details on image streaming please refer to the VT5376 image system user
manual.
20/30
VT5376
General features
Figure 11. Image streaming timing diagram
Motion (48MHz QCLK)
Laser_NEN (FST)
VGate_On (NIB_EVEN)
6 4
2 0
Reset_Out (NIB_ODD)
7 5
3 1
reconstructed pixel data
7.6
pixel_399[7:0]
pixel_0[7:0] pixel_1[7:0]
Optical centre
The optical centre of the VT5376 is NOT in the centre of the package. It is offset by
-0.232 mm in the X axis and +0.217 mm in the Y axis with respect to the centre of the
package as shown in Figure 12. The PCB designer must take this into account when laying
out the PCB.
Figure 12. VT5376 optical centre
Optical centre (-0.232mm, +0.217mm)
Pin 1 marking
mechanical centre
of package (0,0)
TOP VIEW OF VT5376
21/30
General features
7.7
VT5376
Sensor orientation on PCB (with lens)
The VT5376 must be orientated correctly on the PCB in order to move the cursor in the
correct directions when the mouse is moved. This is shown in Figure 13.
Figure 13. VT5376 optical centre
UP
Pin 1 marking
LEFT
RIGHT
VT5376 mounted UNDERNEATH
TOP VIEW of PCB
DOWN
22/30
VT5376
8
Typical application
Typical application
Figure 14. Very low power and low cost wireless laser application
VTOP (>=2.2V)
1.8V
VGATE_ON
VREF
VBAT
VGATE_START
1 AA
PDN*
TEST_CLOCK
VTOP
VREG
DVSS1
1.8V
1 AVSS
AVDD
VTOP
max load = 25mA
SDA
SCL
MOTION
VT5376
RF module
RC_OSC
LASER_OUT
DVSS2
RBIN
DVDD2
LASER_NEN
MCU
BT or 2.4 GHz prop
RESET_OUT
Low Batt
1.8V
buttons/scroll wheel/tilt wheel
PDN* = POWER_DOWN
resolution setting switches
display
23/30
Typical application
8.1
VT5376
Overall 2.4 GHz mouse power consumption example
Assumptions
Table 8.
●
VCSEL, MCU and 2.4 GHz Tx operate from 2.2 V
●
MCU consumes 1 mA in running mode and 50 uA in standby mode. In no motion
period, it remains in standby until it receives an interrupt from the VT5376, indicating
that MOTION has been detected.
●
2.4 GHz Tx consumes 10 mA, but data is sent by bursts of 500 µs every 5 ms (that is
Nordic nRF2402).
●
Maximum current is delivered to VCSEL (10 mA strobed).
●
DCDC efficiency is 70%
●
Ambient temperature
Power supply and typical power consumption
Run
Total @Vbat (1.25 V)
4000 fps
2000 fps
1000 fps
18 mA
12 mA
9.3 mA
IDLE1
IDLE2
SLEEP
0.59 mA
0.29 mA
0.24 mA
Using STMicroelectronics battery life model, these values would enable the mouse to
operate for 12 months from two AA batteries in parallel.
24/30
VT5376
Pinout
VGATE_ON
POWERDOWN
AVDD
TEST_CLOCK
AVSS
VTOP
1
VREG
Figure 15. Pinout
DVSS1
9
Pinout
SDA
VREF
SCL
VBAT
MOTION
VT5376
VGATE_START
RC_OSC
LASER_OUT
DVSS2
RBIN
DVDD2
LASER_NEN
RESET_OUT
25/30
Pinout
VT5376
9.1
Pin description
Table 9.
VT5376 pin description
Pin
Pin name
Type
Description
Comment
1
AVDD
PWR
1.8 V regulated and analog supply
Connect to VREG/DVDD
2
VGATE_ON
I/O
Digital IO
Supplied by VTOP
3
VREF
ANA
Analog ref input
To set VTOP
4
VBAT
PWR
Single battery supply
int DCDC: 1.0 V to 1.6 V
ext: 1.0 V to 1.9 V
5
VGATE_START
ANA
Output
Supplied by Vbat
6
LASER_OUT
ANA
Laser drive set by internal DAC
7
RBIN
ANA
Sets maximum laser/led current
Typical 12K ohms
8
LASER_NEN
I/O
Laser enable
Active low
17
RESET_OUT
I/O
Digital IO
1.8V only
18
DVDD2
PWR
1.8 V regulated and digital supply
Connect to VREG
19
DVSS2
PWR
Digital Ground
20
RC_OSC
ANA
6 MHz Oscillator
Connect 33pF to ground
21
MOTION
I/O
Digital IO
1.8V only
22
SCL
I/O
Digital IO
5V tolerant
23
SDA
I/O
Digital IO
5V tolerant
25
POWERDOWN
I/O
Digital IO
Active high
26
TEST_CLOCK
I/O
Digital IO
Connect to ground
28
VTOP
PWR
Power supply for internal regulators
int DCDC: 2.0 V to 2.6 V
Ext: 1.8 V +/-0.1 V
29
VREG
PWR
1.8 V regulated supply
Connect to DVDD/AVDD
31
DVSS1
PWR
Digital ground
32
AVSS
PWR
Analog ground
Note:
26/30
All other pins are NOT CONNECTED.
VT5376
10
Package mechanical data
Package mechanical data
Figure 16. TQFP32 clear resin body 7.0 x 7.0 x 1.40 footprint 1.0
27/30
Package mechanical data
Table 10.
VT5376
TQFP dimensions (mm)
Reference
Minimum (mm)
Typical (mm)
A
1.600
A1
0.050
A2
1.350
1.400
1.450
B
0.300
0.370
0.450
c
0.090
0.200
9.000
D1
7.000
D3
5.600
e
0.800
E
9.000
E1
7.000
E3
5.600
0.450
L1
k
10.1
0.150
D
L
Note:
Maximum (mm)
0.600
0.750
1.000
0d
3.5d
W1
5.000
W2
0.650
1
Surface finish W1 is 0.07 Ra.
2
Ejectors are on 5.2 mm square for both top and bottom package.
3
On top package, only the pin 1 identification is not an engraved ejector.
7d
TQFP package guidelines
The IC can be exposed a maximum of two times to an IR/Convection reflow solder process
having a temperature profile peak of no higher than 240 ° C.
The package/chip are lead free and is ROHS compliant.
For full handling guidelines please contact ST (document reference 7310263).
28/30
VT5376
11
Ordering information
Ordering information
Table 11.
Ordering information
Order code
VT5376V032
Table 12.
Package
Packing
TQFP32 OPTO 7 mm x 7 mm x 1.4 mm
Tray
Evaluation boards ordering information
Order code
12
Description
STV-376-E01
USB2 VT5376 high-speed imaging system evaluation board
STV-376-E02
VT5376 sensor in a full-speed wired laser mouse evaluation board
STV-376-E03
VT5376 sensor in a low-speed wireless laser mouse evaluation board
Revision history
Table 13.
Document revision history
Date
Revision
27-Sep-2007
1
Initial release.
2
Updated
– Chapter 1: Motion performance
– Chapter 2: Power supply options and power consumption
– Chapter 3: Electrical characteristics
– Chapter 5: I2C control register map
– Chapter 6: Laser
– Chapter 7: General features
– Chapter 8: Typical application
– Chapter 9: Pinout
– Chapter 10: Package mechanical data
– Chapter 11: Ordering information
– Image download sections (Section 7.4 and Section 7.5)
09-Sep-2008
Changes
29/30
VT5376
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