The following registers are also enable-protected according their corresponding enable bit:
•
Frame Counter 0 register (FC0) enabled-protected by Frame Counter 0 Enable (CTRLD.FC0EN)
•
Frame Counter 1 register (FC1) enabled-protected by Frame Counter 1 Enable (CTRLD.FC1EN)
•
Frame Counter 2 register (FC2) enabled-protected by Frame Counter 2 Enable (CTRLD.FC2EN)
Enable-protected bits in the CTRLA register can be written at the same time as CTRLA.ENABLE is
written to '1', but not at the same time as CTRLA.ENABLE is written to '0'.
Enable-protection is denoted by the Enable-Protected property in the register description.
43.6.1.2. Enabling, Disabling, and Resetting
The SLCD is enabled by writing a '1' to the Enable bit in the Control A register (CTRLA.ENABLE). The
SLCD is disabled by writing a '0' to CTRLA.ENABLE. To stop driving the LCD panel properly, SLCD will
be disabled after the current frame is completed. The Enable bit in the Synchronization Busy register
(SYNCBUSY.ENABLE) will thus be cleared at the end of the frame.
The SLCD is reset by writing a '1' to the Software Reset bit in the Control A register (CTRLA.SWRST). All
registers in the SLCD will be reset to their initial state, and the SLCD will be disabled.
Software reset will stop waveforms generation of the current frame. For this reason it is recommended to
disable SLCD first.
43.6.1.3. LCD Display
The display memory stores the values of all segments to display. The display memory is accessible
through APB, and should be filled before the next frame starts. A start of a new frame triggers copying the
display memory into the shadow display memory. A display memory refresh is thus possible without
affecting data already sent to the panel.
Note:
The display memory is not initialized at startup.
When a bit in the display memory is written to '1', the corresponding segment will be energized (ON /
opaque), and de-energized (OFF / transparent) when this bit is written to '0'.
Each COM signal has identical waveforms but different phases. The maximum amplitude (VLCD) occurs
during the corresponding phase of the frame (phase 0 for COM0, phase 1 for COM1 etc.). Otherwise, the
signal amplitude is one of the bias voltages (depending on the bias setting).
The SEG lines are controlled according to the corresponding value in shadow display memory. For each
phase of the frame, SEG lines are driven to VLCD and GND when the pixel is ON, or to one of the bias
voltages when the pixel is OFF.
43.6.1.4. Operating Modes
SLCD supports up to eight COM and up to three bias voltages. The multiplexing and bias configurations
are set independently by writing to the Duty Ratio bits and to the Bias Setting bits in Control A register
(CTRLA.DUTY and CTRLA.BIAS, respectively). CTRLA.DUTY defines the number of COM lines used
(NB_COM), as shown in the table below, and thus the number of phases.
Table 43-1. Duty Selection (CTRLA.DUTY)
DUTY[2:0]
Duty (NB_COM)
Recommended Bias
COM Pins
0x0
1
Static
COM0
0x1
2
1/2
COM0..1
0x2
3
1/3
COM0..2
0x3
4
1/3
COM0..3
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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