Example Configuration Used in this Application

The following sequence is a basic example to scroll the string “HELLO WORLD ” by using the ACM scrolling mode in Segment LCD1 Xplained Pro LCD glass.

Buffers used :

/* DMA buffer length */
#define BUFFER_LEN 30
/* DMA resource and descriptor */
struct dma_resource example_resource;

COMPILER_ALIGNED(16)
DmacDescriptor example_descriptor;

static char user_scrolling_str[BUFFER_LEN] = {"HELLO WORLD     "};
static volatile uint32_t dma_source_buf[BUFFER_LEN];

static volatile bool transfer_is_done = false;
static volatile uint32_t dma_break = 0, dma_block_count = 0;

Disable SLCD:
```
slcd_disable();
```

Disable SLCD, disable all the previous running mode, and clear the SLCD screen:
```
xpro_lcd_clear_all();
```

Load the user input string from user_scrolling_str[] to dma_source_buf[]
This step includes the conversion of the ASCII value of each character in the Scrolling string user_scrolling_str[] into equivalent segment value from the lookup table array DIGI_LUT[] and find the block count. (Refer to Figure 2 to find the segment values different characters.)

Create SLCD configuration structure, check whether ACM scrolling mode is selected using the flag is_scrolling, get the default configuration of ACM mode, and load the configuration structure with the following configuration parameters for the ACM scrolling mode:

/*Structure for the ACM configurations */
struct slcd_automated_char_config automated_char_config;

/** CMCFG.DEC = 0 CMCFG.NSEG = 3 ACMCFG.NDROW = 5 ACMCFG.STSEG = 4
* ACMCFG.NDIG = 5 ACMCFG.STEPS = string length - NDIG + 1
* ACMCFG.MODE = 1 ACMCFG.FCS = 1 */


if(true == is_scrolling ){
    /*configuration for Auto character mapping scrolling mode */ 
    /* Get default config for the ACM mode */
    slcd_automated_char_get_config_default(&automated_char_config);
    
    /* Segment mapping order (CMCFG.DEC bit) */ 
    automated_char_config.order = 0;
    /** select the number of segment used per digit                    
    * it equal to number of SEG line - 1 (CMCFG.NSEG) */
    automated_char_config.seg_line_num = 3;
    
    /* Define the number of digit per row. (ACMCFG.NDROW) */
    automated_char_config.row_digit_num = 5;
    /** Define the index of the first segment terminal of the 
    * digit to display (ACMCFG.STSEG) */
    automated_char_config.start_seg_line = 4;
    /** Define the number of digit, it must be greater than 1.
    * (ACMCFG.NDIG)*/
    automated_char_config.digit_num = 5;
    
    /* STEPS = string length - NDIG + 1 (ACMCFG.STEPS) */
    automated_char_config.scrolling_step = dma_block_count – 5 + 1;
    /* Select the ACM mode (ACMCFG.MODE) */ 
    automated_char_config.mode  = SLCD_AUTOMATED_CHAR_SCROLL;
    /* Select the frame counter for the ACM mode (ACMCFG.FCS) */
    automated_char_config.fc = SLCD_FRAME_COUNTER_1;
    
    /*Configure the mask value in the CMDMASK register */
    automated_char_config.data_mask = 0x00FF4002;
}

Write the above configuration for the ACM scrolling mode by using the following function:

/* write the SLCD ACM configurations in the respective registers */
slcd_automated_char_set_config(&automated_char_config);

Write the above configuration for the ACM scrolling mode by using the following function:

/* write the SLCD ACM configurations in the respective registers */
slcd_automated_char_set_config(&automated_char_config);

Write the frame counter configurations:

/* Set the frame counter configurations and enable it */
slcd_set_frame_counter(automated_char_config.fc,0,0x1);
slcd_enable_frame_counter(automated_char_config.fc);

Enable SLCD:
```
slcd_enable();
```

Create the DMA resource configuration structure, get the default configuration of DMA resource configuration, check whether ACM scrolling mode is selected using the flagis_scrolling, and load the configuration structure with the following configuration parameters for the ACM scrolling mode:
```
/* Structure for the DMA resource configurations */
struct dma_resource_config config;
/* Get the default configuration */
dma_get_config_defaults(&config);

if( true == is_scrolling ){
    /* Set the peripheral trigger source */
    config.peripheral_trigger = SLCD_DMAC_ID_ACMDRDY;
    /* Set the trigger action */
    config.trigger_action = DMA_TRIGGER_ACTON_BEAT;
}
```

Write the above DMA resource configuration for the ACM scrolling mode by using the following function:
```
configure_dma_resource(&example_resource);
```

Create the DMA descriptor configuration structure, check whether ACM scrolling mode is selected using the flag is_scrolling, get the default configuration of DMA resource configuration, and load the configuration structure with the following configuration parameters for the ACM scrolling mode:

/* Structure for the DMA descriptor configurations */
struct dma_descriptor_config descriptor_config;

if( true == is_scrolling ){
    /* Get the default configuration */
    dma_descriptor_get_config_defaults(&descriptor_config);
    
    descriptor_config.beat_size = DMA_BEAT_SIZE_WORD;
    descriptor_config.src_increment_enable = true;
    descriptor_config.dst_increment_enable = false; 
    descriptor_config.step_size = (DMA_ADDRESS_INCREMENT_STEP_SIZE_1);
    descriptor_config.step_selection = DMA_STEPSEL_SRC;
    descriptor_config.block_action = DMA_BLOCK_ACTION_INT;

    /* Block count manipulated run time from the scrolling string */
    descriptor_config.block_transfer_count = dma_block_count;
    descriptor_config.source_address = (uint32_t)dma_source_buf +
                                 (dma_block_count * sizeof(dma_source_buf[0]));
    descriptor_config.destination_address = (uint32_t)(&SLCD->CMDATA.reg);
    descriptor_config.next_descriptor_address =( uint32_t )descriptor;
    
    /* Create a DMA descriptor */
    dma_descriptor_create(descriptor, &descriptor_config);
}

Write the above DMA descriptor configuration for the ACM scrolling mode by using the following function:
```
configure_dma_descriptor(&example_resource);
```

Create the call back function, register call back, and enable:

dma_register_callback(&example_resource, dma_callback,DMA_CALLBACK_TRANSFER_DONE);
dma_enable_callback(&example_resource, DMA_CALLBACK_TRANSFER_DONE);

Start the DMA transfer:

/** Start DMA transfer once DMA gets the peripheral
* trigger form the ACM then the data transfer starts */
dma_start_transfer_job(&example_resource);

Enable the ACM mode:

/* Enable ACM mode */
slcd_enable_automated_character();