tcs3771 ETC-unknow, tcs3771 Datasheet - Page 10

• Manufacturer Part Number: tcs3771
• Description: Color Light-to-digital Converter With Proximity Sensing
• Manufacturer: ETC-unknow

TCS3771
COLOR LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS110A − MARCH 2011
RGBC Operation
10
Copyright E 2011, TAOS Inc.
The RGBC engine contains RGBC gain control (AGAIN) and four integrating analog-to-digital converters (ADC)
for the RGBC photodiodes. The RGBC integration time (ATIME) impacts both the resolution and the sensitivity
of the RGBC reading. Integration of all four channels occurs simultaneously and upon completion of the
conversion cycle, the results are transferred to the color data registers. This data is also referred to as channel
count. The transfers are double-buffered to ensure that invalid data is not read during the transfer. After the
transfer, the device automatically moves to the next state in accordance with the configured state machine.
The registers for programming the integration and wait times are a 2’s compliment values. The actual time can
be calculated as follows:
Inversely, the time can be calculated from the register value as follows:
For example, if a 100-ms integration time is needed, the device needs to be programmed to:
Conversely, the programmed value of 0xC0 would correspond to:
Clear
ATIME = 256 − Integration Time / 2.4 ms
Integration Time = 2.4 ms
256 − (100 / 2.4) = 256 − 42 = 214 = 0xD6
(256 − 0xC0)
Red
Green
2.4 ms to 700 ms
Blue
ATIME(r 1)
×
r
Green ADC
Clear ADC
Blue ADC
Red ADC
Figure 8. RGBC Operation
2.4 = 64
RGBC Control
www.taosinc.com
×
Green Data
×
Clear Data
2.4 = 154 ms.
Blue Data
Red Data
(256 − ATIME)
AGAIN(r 0x0F, b1:0)
1y, 4y, 16y, 60y Gain
CDATAH(r 0x15), CDATA(r 0x14)
GDATAH(r 0x19), GDATA(r 0x18)
BDATAH(r 0x1B), BDATA(r 0x1A)
RDATAH(r 0x17), RDATA(r 0x16)
r
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