ADC Device

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ADC Device

Open ADC Device

int mr_dev_open(const char *name, int oflags);

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

name: ADC device name usually is: adcx, adc1, adc2.
oflags: Open device flags, support MR_OFLAG_RDONLY.

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

Close ADC 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.

Control ADC 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_CTL_ADC_SET_CHANNEL: Set channel number.
- MR_CTL_ADC_SET_CHANNEL_STATE: Set channel state.
- MR_CTL_ADC_GET_CHANNEL: Get channel number.
- MR_CTL_ADC_GET_CHANNEL_STATE: Get channel state.

Set/Get Channel Number

Channel number range: 0 ~ 31.

/* Define channel number */
#define CHANNEL_NUMBER                  5

/* Set channel number */  
mr_dev_ioctl(ds, MR_CTL_ADC_SET_CHANNEL, mr_make_local(int, CHANNEL_NUMBER));

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

Set/Get Channel Status

Channel status:

MR_ADC_STATE_DISABLE: Disable channel.
MR_ADC_STATE_ENABLE: Enable channel.

/* Set channel status */
mr_dev_ioctl(ds, MR_CTL_ADC_SET_CHANNEL_STATE, mr_make_local(int, MR_ADC_STATE_ENABLE)); 

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

Read ADC Device Channel Value

ssize_t mr_dev_read(int desc, void *buf, size_t size);

Parameter	Description

desc	Device descriptor
buf	Read data buffer
size	Read data size
Return Value
`>=0`	Read data size
`<0`	Error code

/* Read channel value */
uint32_t data;
int ret = mr_dev_read(ds, &data, sizeof(data));
/* Check if read successfully */
if (ret != sizeof(data))
{
    return ret;  
}

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

Usage Example:

#include "include/mr_lib.h"

/* Define channel number */
#define CHANNEL_NUMBER                  5

/* Define ADC device descriptor */  
int adc_ds = -1;

int adc_init(void)
{
   int ret = MR_EOK;

   /* Initialize ADC */
   adc_ds = mr_dev_open("adc1", MR_OFLAG_RDONLY);
   if (adc_ds < 0)
   {
       mr_printf("ADC1 open failed: %s\r\n", mr_strerror(adc_ds));
       return adc_ds;
   }
   /* Print ADC descriptor */
   mr_printf("ADC1 desc: %d\r\n", adc_ds);
   /* Set to channel 5 */
   mr_dev_ioctl(adc_ds, MR_CTL_ADC_SET_CHANNEL, mr_make_local(int, CHANNEL_NUMBER));
   /* Set channel enable */
   ret = mr_dev_ioctl(adc_ds, MR_CTL_ADC_SET_CHANNEL_STATE, mr_make_local(int, MR_ADC_STATE_ENABLE));
   if (ret < 0)
   {
       mr_printf("Channel5 enable failed: %s\r\n", mr_strerror(ret));
       return ret;
   }
   return MR_EOK;
}
/* Export to automatic initialization (APP level) */
MR_APP_EXPORT(adc_init); 

int main(void)
{
   /* Automatic initialization (adc_init function will be automatically called here) */
   mr_auto_init();

   while(1)
   {
       uint32_t data;
       int ret = mr_dev_read(adc_ds, &data, sizeof(data));
       if (ret != sizeof(data)) 
       {
           mr_printf("Read failed: %s\r\n", mr_strerror(ret));
       }
       mr_printf("ADC value: %d\r\n", data);
       mr_delay_ms(1000);
   }
}

Enable ADC1 channel 5, read the ADC value every second and print it.

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