TCS3404_11 Datasheet, PDF (10/41 Pages) ams AG – DIGITAL COLOR SENSORS

PRINCIPLES OF OPERATION
TCS3404, TCS3414
DIGITAL COLOR SENSORS
TAOS137A − APRIL 2011
Analog-to-Digital Converter
The TCS3404/14 contains four integrating analog-to-digital converters (ADC) that integrate the currents from
the four photodiodes (channel 1 through channel 4). Integration of all four channels occurs simultaneously, and
upon completion of the conversion cycle the conversion results are transferred to the channel data registers,
respectively. The transfers are double-buffered to ensure that invalid data is not read during the transfer. After
the transfer, the device automatically begins the next integration cycle.
There are two ways to control the integration cycles: internally timed and externally timed. Internally-timed
lid ^{integration cycles can either be continuous back-to-back conversions or can be externally triggered as a single}
event using the SYNC pin. Externally-timed integrations can be controlled by setting and clearing a register bit
(i.e. ADC_EN in Control Register) using the serial interface, or by 1 or more pulses input to the SYNC pin.
a Integration options are configured through the Timing Register (see the Timing Register section for more
information).
v _{Digital Interface}
ill ^{Interface and control of the TCS3404/14 is accomplished through a two-wire serial interface to a set of registers}
that provide access to device control functions and output data. The serial interface is compatible with System
t _{Management Bus (SMBus) versions 1.1 and 2.0, and I}2_{C bus Fast-Mode.}
G _{s The TCS3404/14 device supports a single slave address outlined in Table 1. Additional devices shown in the}
Available Options table on page 3 support additional I²C slave addresses for systems requiring more than one
A ^{t device.}
s ^{n Table 1. Slave Address}
SLAVE ADDRESS
e _0111001
SMB ALERT ADDRESS
0001100
m ^t _{NOTE: The slave and SMB Alert addresses are 7 bits. Please note the SMBus and I}2_{C protocols on the following pages. A read/write bit should}
a ^{n be appended to the slave address by the master device to communicate properly with the device.}
o _Interrupt
c _{Although the ADC channel data registers can be read at any time to obtain the most recent conversion value,}
l ^{in some applications, periodic polling of the device may not be desirable. For these types of applications, the}
device supports a variety of interrupt options allowing the user to configure the device to signal when a change
a in light intensity has occurred. High and low threshold registers allow a range of light levels to be defined, outside
of which the device generates an interrupt. A persistence setting allows the user to specify a time duration that
ic ^{the measured value must remain outside of the defined range before generating an interrupt. The interrupt}
function can be assigned to any one of the four ADC color channels. See Interrupt Control Register for more
Techn ^{information on configuring the interrupt functions.}
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Copyright E 2011, TAOS Inc.
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