LCD Frame Frequency

The LCD frame frequency is defined as the number of times the segments are energized per second. The optimal frame frequency should be in range from 30Hz up to 100Hz to avoid flickering and ghosting effect. Frame frequency (or frame rate) depends on the parameters such as SLCD clock source 32KHz oscillator clock CLK_SLCD_OSC, duty setting (CTRLA.DUTY[2:0] bits). prescaler setting (CTRLA.PRESC[1:0] bits), and Clock Divider settings (CTRLA.CKDIV[2:0] bits).

Figure 1. Framerate

For this application the frame rate is calculated as 32Hz with 1/4 DUTY and 32768Hz input clock (CLK 32768 Hz, Prescaler 32 and CKDIV value is 7).

FrameRate = 32768/(32*(7+1)*4) = 32Hz.


The example values for the various configurations to select the FrameRate is given in the device datasheet.