PCA9901_1

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 01 — 3 December 2009

6 of 27

NXP Semiconductors

PCA9901

One wire single LED driver

8.2 Command descriptions

8.2.1 TRAINING START command

2 pulses sent to the PCA9901 in less than 1.5 ms causes the PCA9901 to enter the

Training mode.

resets its registers to zeroes and is ready for sequence capture within the 1.5 ms.

The next assertion of the CTRL pin (LOW to HIGH transition) starts the first LED ON

period capture. CTRL cannot be asserted in less than 1.5 ms after the TRAINING START

command has been issued.

8.2.2 TRAINING END command

3 pulses sent to the PCA9901 in less than 1.5 ms causes the PCA9901 to leave the

Training mode.

The PCA9901 ends the last LED OFF period capture when the TRAINING END command

occurs.

The PCA9901 goes to Shutdown mode.

8.2.3 RUN ONCE command

4 pulses sent to the PCA9901 in less than 1.5 ms causes the device to enter the

RUN ONCE mode and wait for a ‘synchronization’ rising edge on CTRL.

When a rising edge on CTRL is detected, the sequence that has been previously captured

is run once. If no sequence has been captured it will go into Shutdown mode.

Once the sequence has been run, the PCA9901 goes to Shutdown mode.

Remark: CTRL line may stay either HIGH or LOW after the ‘synchronization’ edge.

8.2.4 RUN command

A LOW to HIGH transition followed by a HIGH state longer than 1.5 ms causes the

sequence that has been previously captured to be executed in loop. The CTRL pin stays

HIGH as long as the sequence is executed. If no sequence has been captured it will go

into Shutdown mode.

8.2.5 STOP command

A HIGH to LOW transition when the PCA9901 is in the RUN mode causes the sequence

that is running to stop:

during the LED ON time.

Once the sequence has been stopped, the PCA9901 goes to Shutdown mode.