TCS3772

COLOR LIGHT-TO-DIGITAL CONVERTER

with PROXIMITY SENSING

TAOS145B − SEPTEMBER 2012

14

r

r

Copyright

E 2012, TAOS Inc.

The LUMENOLOGY

r Company

www.taosinc.com

System Timing

The system state machine shown in Figure 9 provides an overview of the states and state transitions that

provide system control of the device. This section highlights the programmable features, which affect the state

machine cycle time, and provides details to determine system level timing.

When the proximity detection feature is enabled (PEN), the state machine transitions through the Prox Accum,

Prox Wait, and Prox ADC states. The Prox Wait time is a fixed 2.4 ms, whereas the Prox Accum time is

determined by the number of proximity LED pulses (PPULSE) and the Prox ADC time is determined by the

integration time (PTIME). The formulas to determine the Prox Accum and Prox ADC times are given in the

associated boxes in Figure 14. If an interrupt is generated as a result of the proximity cycle, it will be asserted

at the end of the Prox ADC state.

When the power management feature is enabled (WEN), the state machine will transition in turn to the Wait

state. The wait time is determined by WLONG, which extends normal operation by 12

WTIME. The formula to determine the wait time is given in the box associated with the Wait state in Figure 14.

When the RGBC feature is enabled (AEN), the state machine will transition through the RGBC Init and RGBC

ADC states. The RGBC Init state takes 2.4 ms, while the RGBC ADC time is dependent on the integration time

(ATIME). The formula to determine RGBC ADC time is given in the associated box in Figure 14. If an interrupt

is generated as a result of the RGBC cycle, it will be asserted at the end of the RGBC ADC.

Prox

Wait

Sleep

Idle

Wait

Prox

Accum

RGBC

ADC

RGBC

Init

RGBC

Prox

ADC

Prox

PPULSE: 0 ~ 255 pulses

Time: 14.0

μs/pulse

Range: 0 ~ 3.6 ms

Time: 2.4 ms

PTIME: 1 ~ 256 steps

Time: 2.4 ms/step

Range: 2.4 ms ~ 614 ms

WTIME: 1 ~ 256 steps

WLONG = 0

WLONG = 1

Time:

2.4 ms/step

28.8 ms/step

Range:

2.4 ms ~ 614 ms

28.8 ms ~ 7.37s

Time: 2.4 ms

ATIME: 1 ~ 256 steps

Time: 2.4 ms/step

Range: 2.4 ms ~ 614 ms

!WEN &

!AEN

AEN

!PON

WEN

!AEN

!PEN & WEN

& AEN

!WEN &

AEN

Notes: 1. There is a 2.4 ms warm-up delay if PON is enabled. If PON is not enabled, the device will return to the Sleep state as shown.

2. PON, PEN, WEN, and AEN are fields in the Enable register (0x00).

!PEN & !WEN

& AEN

PEN

(Note 1)

Figure 14. Detailed State Diagram