This feature is used to write the display memory for the each character by giving the character start index, segment data, and mask value.
In this mode, multiple segments of the LCD panel can be gathered into digits in order to display as characters. Digits can be of various types (e.g., 7-segment, 16-segment) and mapped in the display memory accordingly. We can find the different memory mapping scenarios in the device datasheet. The SLCD supports displaying up to 24-segment characters on any existing LCD panel.
The user can change the mapping order by configuring the CMCFG.DEC bit to match the display memory mapping to their SLCD segment order.
The CMCFG.NSEG defines the number of segments used to map a single digit. It should be the number of SEG line - 1. In the figure below each digit requires four segment lines. So the value for NSEG = 3.
| Segments | COM0 | COM1 | COM2 | COM3 | Comments |
|---|---|---|---|---|---|
| SEG0 | G1 | G2 | G4 | G3 | Atmel logo, four stage battery-, Dot-point-, usb-, and play indicator |
| SEG1 | G0 | G6 | G7 | G5 | |
| SEG2 | E7 | E5 | E3 | E1 | Four stage wireless-, AM-, PM- Volt-, and millivolt indicator |
| SEG3 | E6 | E4 | E2 | E0 | |
| SEG4 | A0-h | A0-i | A0-k | A0-n | 1st 14-segment character |
| SEG5 | B3 | A0-f | A0-e | A0-d | |
| SEG6 | A0-a | A0-b | A0-c | B4 | |
| SEG7 | A0-g | A0-j | A0-l | A0-m | |
| SEG8 | A1-h | A1-i | A1-k | A1-n | 2nd 14-segment character |
| SEG9 | B2 | A1-f | A1-e | A1-d | |
| SEG10 | A1-a | A1-b | A1-c | B5 | |
| SEG11 | A1-g | A1-j | A1-l | A1-m | |
| SEG12 | A2-h | A2-i | A2-k | A2-n | 3rd 14-segment character |
| SEG13 | B1 | A2-f | A2-e | A2-d | |
| SEG14 | A2-a | A2-b | A2-c | B6 | |
| SEG15 | A2-g | A2-j | A2-l | A2-m | |
| SEG16 | A3-h | A3-i | A3-k | A3-n | 4th 14-segment character |
| SEG17 | B0 | A3-f | A3-e | A3-d | |
| SEG18 | A3-a | A3-b | A3-c | B7 | |
| SEG19 | A3-g | A3-j | A3-l | A3-m | |
| SEG20 | A4-h | A4-i | A4-k | A4-n | 5th 14-segment character. Celsius and Fahrenheit indicator. |
| SEG21 | B8 | A4-f | A4-e | A4-d | |
| SEG22 | A4-a | A4-b | A4-c | B9 | |
| SEG23 | A4-g | A4-j | A4-l | A4-m |
In the figure above the Segment LCD1 Xplained Pro LCD requires four segment lines and four com lines in each digit (14 segment per character). Icons starts from seg0 and alphanumeric digit starts from segment 4/8/12/16/20. When we match the segment mapping with display memory mapping, we can get the mapping order as shown in Figure 2.
In this mode to write the character value in the segment memory register, the CMDATA register is used. Since the CMDATA register can be up to 24 bits, a mask can be configured to write only selected bits. Based on the user SLCD glass an unwanted bit can be masked by writing a '1' to a bit in the Character Mapping Data Mask register (CMDMASK). Then this bit will not be written in the display memory when CMDATA register is written.
| SEG4 | A0-h | A0-i | A0-k | A0-n | 1st 14-segment character |
| SEG5 | B3 | A0-f | A0-e | A0-d | |
| SEG6 | A0-a | A0-b | A0-c | B4 | |
| SEG7 | A0-g | A0-j | A0-l | A0-m |