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diff --git a/watch-library/hal/documentation/slcd_sync.rst b/watch-library/hal/documentation/slcd_sync.rst new file mode 100644 index 00000000..e18aa9dd --- /dev/null +++ b/watch-library/hal/documentation/slcd_sync.rst @@ -0,0 +1,82 @@ + +SLCD Synchronous driver +======================= + +An LCD display is made of several segments (pixels or complete symbols) which +can be block light or let light through. In each segment is one electrode +connected to the common terminal (COM pin) and one is connected to the segment +terminal (SEG pin). When a voltage above a certain threshold level is applied +across the liquid crystal, it will change orientation and either let light +through or block it. + +The driver supports segment on/off/blink, animation and character display. + +Each segment has a unique int32 segment id which is used by the driver. The id is +combined by common number(COM) and segment number(SEG), the COM and SEG start from 0. +The unique segment id is calculated by this formula: (COM << 16) | SEG +For example a 8(coms)*8(segments)SLCD, the unique segment id for segment should be + + +-----+-----+---------+ + | COM | SEG | ID | + +-----+-----+---------+ + | 0 | 0 | 0x00000 | + +-----+-----+---------+ + | 1 | 0 | 0x10000 | + +-----+-----+---------+ + | 7 | 7 | 0x70007 | + +-----+-----+---------+ + +Segment ID can be calculated using the pre-defined macro SLCD_SEGID(com, seg). + +For character display, the "segment character mapping table" and "character mapping table" +should be setup in configuration. The driver have no API to setup/change those +mapping setting. +There are two pre-defined "segment character mapping table" in this driver, 7 segments +and 14 segments. The 7 segment character mapping can display 0-9 and a-f, the 14 +segments character mapping can display 0-9, A-Z and some special ASCII, for more +details please refer to hpl_slcd_cm_7_seg_mapping.h and hpl_slcd_cm_14_seg_mapping.h. +Application can also adjust this mapping table in the configuration header file, +to add more character mapping or remove some unused character. + +The "character mapping" is used to setup each character in SLCD display screen. +The driver supports multiple character mapping, the max number varies on different +MCU/MPU. For example if an LCD display screen has five "7-segments character" and +eight "14-segments character", and the MCU support max 44 characters setting, then +the 13 character should be setup in configuration. Application can select any +position from those 44 characters setting to save those 13 character. +The index of character setting will be used in the driver API. For example: +five "7-segments character" setting to 0 to 4 and eight "14-segments character" setting +to 10 to 17. Then the application can use index from 0 to 4 to display the +"7-segments character" and use index from 10 to 14 to display "14-segments character". + +Features +-------- + +* Initialization and de-initialization +* Enabling and Disabling +* Switching segment on/off +* Set segment blink +* Autonomous animation +* Character display + +Applications +------------ +* SLCD display control, segment on/off/blink +* Play battery animation, running wheel, wifi signal, etc. +* Display Time Clock by 7 segments character mapping +* Display ASCII character by 14 segments character mapping + +Dependencies +------------ +* SLCD capable hardware + +Concurrency +----------- +N/A + +Limitations +----------- + +Known issues and workarounds +---------------------------- +N/A |