UM0851 datasheet(187/245 Pages) STMICROELECTRONICS

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UM0851

Human interface device (HID) drivers

Doc ID 16604 Rev 2

187/245

Common configuration of all ADC channels can be done using the following calls:

User level:

ioctl(fd, ADCIOC_CONFIG, &config);

On success, zero is returned otherwise -1 is returned and errno is set appropriately.

Kernel level:

spear_adc_configure(dev, ADC_CHANNEL0, &config);

On success, zero is returned otherwise negative standard kernel errors are returned.

The above functions will be successful if the ADC is not being used by another user.

In the function calls, config is an instance of struct adc_config:

struct adc_config {

enum adc_conv_mode mode; /* mode to be configured, can be single or

continuous . */

enum adc_volt_ref volt_ref; /* reference of voltage, can be internal

or external

unsigned int mvolt; /* This is reference voltage applied to ADC. It

will be useful in calculating output voltage in

millivolts. Provide mvolt in millivolt. */

enum adc_scan_ref scan_ref; /* reference of scan rate, can be internal or

external */

#ifdef CONFIG_MACH_SPEAR300

enum adc_resolution resolution; /* resolution of output data, can be

normal, 10 bit, or high, 17 bit, only

for SPEAR300*/

#endif

unsigned int req_clk; /* ADC clock requested, in Hz

unsigned int avail_clk; /* closest clock less than equal to req_clk

possible, in Hz

};

The default configuration done at initialization is:

struct adc_config adc_config = {

.mode = CONTINUOUS_CONVERSION;

.volt_ref = EXTERNAL_VOLT;

.mvolt = 2500,

.scan_ref = INTERNAL_SCAN;

#ifdef CONFIG_MACH_SPEAR300

.resolution = NORMAL_RESOLUTION;

#endif

.req_clk = 14000000};

ADC channel configuration

Channel configuration can be done using the following calls:

User level:

ioctl (fd, ADCIOC_CHAN_CONFIG, &chan_config);

On success, a zero is returned otherwise -1 is returned and errno is set appropriately.

UM0851 Datasheet(PDF) 187 Page - STMicroelectronics

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