AS3668 datasheet(37/60 Pages) AMSCO

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AS3668

Data Sheet - D e t a i l e d D e s c r i p t i o n

As the example shows, each defined pattern, no matter if it is a single pulse or multiple pulse pattern, can be divided into frames which are

basically running in parallel mode. The pattern which has be defined with the different parameters like tr_CURR, ton_CURR, toff_CURR and

tp_CURR is repeated in an endless loop. In order to enhance the functionality of the pattern generation it is possible to mask or skip frames in

between the endless pattern loop. Each current source comes with a dedicated register to support masking of one frame up to four frames. This

means the Frame Mask Mode allows the user to individually skip frames in each current source. The example above shows that the Frame Mask

Register fmask_curr2 of CURR2 has been set to 1, which means every second frame will be masked out when playing the pattern. The Frame

Mask Register fmask_curr3 of CURR3 has been set to 2, therefore two frames are masked out in the example. The register fmask_curr4 of

CURR4 has been set to 3, thus three frames are masked out in the example. The frame mask order in the example is not fixed and can be easily

exchanged depending on the Frame Mask Register setting for each current source.

8.10.4 Frame Start Delay Mode

The frame delay mode allows the user to add a start-delay for each current source separately in pattern generation mode. This feature allows an

user to create again more complex lighting patterns like a running LED shown in the example in Figure 46.

Figure 46. Frame Start Delay Mode

Each current source has a dedicated delay register(frame_delay1, frame_delay2, frame_delay3 and frame_delay4) which allow adding different

start delays to each current source. This feature can of course be combined with the frame mask mode described in 8.10.3. In the example

above the frame_delay2 register has been set to 1 to add one frame delay to CURR2. The frame_delay3 register has been set to 2 adding two

frames startup delay to CURR3. CURR4 needs a startup delay of 3 frames which means theframe_delay4 registers must be set to 3. It is worth

mentioning that there are also no restrictions when using this mode together with Single- or Multiple Pulse mode described in chapter 8.10.1 and

8.10.2.

8.10.5 GPIO Toggle Mode

An add on feature which enables the user to use up to eight LEDs in pattern generation mode in a sequential order is the GPIO Toggle mode.

Figure 47. GPIO Toggle Mode 1 Frame

The mode can be enabled with the register gpio_toggle_en. Once the mode has been enabled register gpio_toggle_framenr gets activated and

allows the user to select after how many frames the GPIO/AUDIO_IN pin toggles. An example is shown in Figure 47 above. The gpio_toggle_en

register has been set to 1. The gpio_toggle_framenr register has also been set to 1. The GPIO/AUDIO_IN pin toggles after each frame. The pin

can be used to control an external switch to enable some more LEDs. An example of such an application is shown in Figure 48. Please mind that

it is not possible to operate all eight LEDs in parallel. It is only possible to enable either one or the other block. This mechanism is handled

automatically with the external control transistors.

AS3668 Datasheet(PDF) 37 Page - ams AG