DAC Device

中文

DAC Device

Open DAC Device

int mr_dev_open(const char *path, int flags);

Parameter	Description
path	Device path
flags	Open device flags
Return Value
`>=0`	Device descriptor
`<0`	Error code

path: DAC device path usually is: dacx, dac1, dac2.
flags: Open device flags, support MR_O_WRONLY.

Note: When using, the DAC device should be opened separately for different tasks according to actual situations, and the appropriate flags should be used for management and permission control to ensure they will not interfere with each other.

Close DAC Device

int mr_dev_close(int desc);

Parameter	Description
desc	Device descriptor
Return Value
`=0`	Close successfully
`<0`	Error code

Note: When closing the device, all channels will be automatically restored to the default state. The channel needs to be reconfigured after reopening(This feature can be turned off).

Control DAC Device

int mr_dev_ioctl(int desc, int cmd, void *args);

Parameter	Description
desc	Device descriptor
cmd	Command code
args	Command parameters
Return Value
`=0`	Set successfully
`<0`	Error code

cmd: Command code, supports the following commands:
- MR_IOC_DAC_SET_CHANNEL: Set channel number.
- MR_IOC_DAC_SET_CHANNEL_CONFIG: Set channel configure.
- MR_IOC_DAC_GET_CHANNEL: Get channel number.
- MR_IOC_DAC_GET_CHANNEL_CONFIG: Get channel configure.

Set/Get Channel Number

Channel number range: 0 ~ 31.

/* Define channel number */
#define CHANNEL_NUMBER                  5

/* Set channel number */   
mr_dev_ioctl(ds, MR_IOC_DAC_SET_CHANNEL, MR_MAKE_LOCAL(int, CHANNEL_NUMBER));

/* Get channel number */
int number;  
mr_dev_ioctl(ds, MR_IOC_DAC_GET_CHANNEL, &number);

Independent of DAC interface:

/* Define channel number */
#define CHANNEL_NUMBER                  5

/* Set channel number */   
mr_dev_ioctl(ds, MR_IOC_SPOS, MR_MAKE_LOCAL(int, CHANNEL_NUMBER));

/* Get channel number */
int number;  
mr_dev_ioctl(ds, MR_IOC_GPOS, &number);

Set/Get Channel Configure

Channel configure:

MR_DISABLE: Disable channel.
MR_ENABLE: Enable channel.

/* Set channel status */
mr_dev_ioctl(ds, MR_IOC_DAC_SET_CHANNEL_CONFIG, MR_MAKE_LOCAL(int, MR_ENABLE));

/* Get channel status */   
int state;
mr_dev_ioctl(ds, MR_IOC_DAC_GET_CHANNEL_CONFIG, &state);

Independent of DAC interface:

/* Set channel status */
mr_dev_ioctl(ds, MR_IOC_SCFG, MR_MAKE_LOCAL(int, MR_ENABLE));

/* Get channel status */   
int state;
mr_dev_ioctl(ds, MR_IOC_GCFG, &state);

Write DAC Device Channel Value

ssize_t mr_dev_write(int desc, const void *buf, size_t count);

Parameter	Description
desc	Device descriptor
buf	Write data buffer
count	Write data size
Return Value
`>=0`	Write data size
`<0`	Error code

/* Write channel value */
uint32_t data = 2048;
int ret = mr_dev_write(ds, &data, sizeof(data));
/* Check if write successfully */
if (ret != sizeof(data))
{
    return ret;
}

Note: The write data is the raw DAC data. The minimum write unit is uint32_t, that is, 4 bytes each time.

Usage Example:

#include "include/mr_lib.h"

/* Define channel number */
#define CHANNEL_NUMBER                  1

/* Define DAC device descriptor */   
int dac_ds = -1;

int dac_init(void)
{
   int ret = MR_EOK;

   /* Initialize DAC */
   dac_ds = mr_dev_open("dac1", MR_O_WRONLY);
   if (dac_ds < 0)
   {
       mr_printf("DAC1 open failed: %s\r\n", mr_strerror(dac_ds));  
       return dac_ds;
   }
   /* Print DAC descriptor */
   mr_printf("DAC1 desc: %d\r\n", dac_ds);
   /* Set to channel 1 */
   mr_dev_ioctl(dac_ds, MR_IOC_DAC_SET_CHANNEL, MR_MAKE_LOCAL(int, CHANNEL_NUMBER));
   /* Set channel enable */
   ret = mr_dev_ioctl(dac_ds, MR_IOC_DAC_SET_CHANNEL_CONFIG, MR_MAKE_LOCAL(int, MR_ENABLE));
   if (ret < 0)
   {
       mr_printf("Channel%d enable failed: %s\r\n", CHANNEL_NUMBER, mr_strerror(ret));
       return ret;
   }
   return MR_EOK;
}
/* Export to automatic initialization (APP level) */
MR_INIT_APP_EXPORT(dac_init);

/* Define DAC data maximum value */
#define DAC_DATA_MAX                    4000

int main(void) 
{
   /* Automatic initialization (dac_init function will be automatically called here) */
   mr_auto_init();
    
   while(1)
   {
       uint32_t data = 0;
       for (data = 0; data <= DAC_DATA_MAX; data += 500)
       {
           int ret = mr_dev_write(dac_ds, &data, sizeof(data));
           if (ret != sizeof(data))
           {
               mr_printf("Write failed: %s\r\n", mr_strerror(ret));
           }
           mr_printf("DAC value: %d\r\n", data);
           mr_delay_ms(500);
       }
   }
}

Enable DAC1 channel 1, output the DAC value every 500ms and print it (the output value increases by 500 each time until reaching the maximum value).

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