The device for Mediatek MT6370 RGB LED¶
Description¶
The MT6370 integrates a four-channel RGB LED driver, designed to provide a variety of lighting effect for mobile device applications. The RGB LED devices includes a smart LED string controller and it can drive 3 channels of LEDs with a sink current up to 24mA and a CHG_VIN power good indicator LED with sink current up to 6mA. It provides three operation modes for RGB LEDs: PWM Dimming mode, breath pattern mode, and constant current mode. The device can increase or decrease the brightness of the RGB LED via an I2C interface.
The breath pattern for a channel can be programmed using the “pattern” trigger, using the hw_pattern attribute.
/sys/class/leds/<led>/hw_pattern¶
Specify a hardware breath pattern for a MT6370 RGB LED.
The breath pattern is a series of timing pairs, with the hold-time expressed in milliseconds. And the brightness is controlled by ‘/sys/class/leds/<led>/brightness’. The pattern doesn’t include the brightness setting. Hardware pattern only controls the timing for each pattern stage depending on the current brightness setting.
Pattern diagram:
"0 Tr1 0 Tr2 0 Tf1 0 Tf2 0 Ton 0 Toff" --> '0' for dummy brightness code
^
| ============
| / \ /
Icurr | / \ /
| / \ /
| / \ / .....repeat
| / \ /
| --- --- ---
|--- --- ---
+----------------------------------============------------> Time
< Tr1><Tr2>< Ton ><Tf1><Tf2 >< Toff >< Tr1><Tr2>
Timing description:
Tr1: First rising time for 0% - 30% load.
Tr2: Second rising time for 31% - 100% load.
Ton: On time for 100% load.
Tf1: First falling time for 100% - 31% load.
Tf2: Second falling time for 30% to 0% load.
Toff: Off time for 0% load.
Tr1/Tr2/Tf1/Tf2/Ton: 125ms to 3125ms, 200ms per step.
Toff: 250ms to 6250ms, 400ms per step.
Pattern example:
"0 125 0 125 0 125 0 125 0 625 0 1050"
This Will configure Tr1/Tr2/Tf1/Tf2 to 125m, Ton to 625ms, and Toff to 1050ms.