This feature is used to write the display memory with the sequence of segment values for the predefined symbols automatically by using the Direct Memory Access (DMA). In this Automated Bit Mapping (ABM) mode several segments on the LCD panel can be gathered to make a symbol, which can be animated (i.e., have several states).
Data corresponding to each state of the animation can be stored in the system memory and is transferred periodically to the display memory by using the DMA controller.
To use this mode we need to configure any one of the frame counters among the three independent frame counters FC0, FC1, and FC2 to create a time base.
To make an automated animation of N states with M contiguous segment values in the display memory, the DMA controller must be configured to transfer N x M/8 words (eight contiguous segments are updated per write access).
Here N defines the number of states or frames consist of M contiguous segment values in each state.
M is the number of maximum number segment (24). In a single write the DMA can write eight segments so to write all the segments in the SLCD (for example 24) M/8 DMA writes are required.
In this case for the Segment LCD1 Xplained Pro LCD glass to write all the 24 segments 3 (24 segments/8 segments per write) DMA writes are needed to update all the segment values.
In a single DMA write, the maximum eight bits (for eight segments) can be updated in the display memory by IN-Direct access mode using the ISDATA register. The ISDATA register is 32 bit (one word) wide. It has the following fields.
Format: [00, offset, data mask, data]
Format: [0x00, offset:[21-16], data mask:[15-8], data:[7-0]]
Each DMA write needs 32-bit value in the above mentioned format with the 8-bit segment data.
To write more than eight bits the DMA controller must be configured to transfer multiple words. This number of words must be written to the Size bits in the Automated Bit Mapping Configuration register (ABMCFG.SIZE). It defines the number of DMA writes to the display memory to form an animation frame.
N defines the number of states or frames consist of M contiguous segment values in each state.
Indirect addressing format:
Format: [00, offset, data mask, data]
Format: [0x00, offset:[21-16], data mask:[15-8], data:[7-0]]
Frame /state 0[0][4] = { 0x00000040, 0x00020040, 0x00060040, 0x00010040}
Frame /state 1[1][4] = { 0x00000000, 0x00020000, 0x00060000, 0x00010000}
Frame /state 2[2][4] = { 0x00000010, 0x00020010, 0x00060020, 0x00010020}
Frame /state 3[3][4] = { 0x00000040, 0x00020040, 0x00060040, 0x00010040}
