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cpu/lpc11u34: fixed ADC resolution selection #6959

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merged 1 commit into from
Aug 24, 2017
Merged

cpu/lpc11u34: fixed ADC resolution selection #6959

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16 changes: 7 additions & 9 deletions cpu/lpc11u34/include/periph_cpu.h
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Original file line number Diff line number Diff line change
Expand Up @@ -44,10 +44,8 @@ extern "C" {

/**
* @brief Define number of available ADC lines
*
* TODO: check this value
*/
#define ADC_NUMOF (10U)
#define ADC_NUMOF (8U)

/**
* @brief Override the default GPIO type
Expand Down Expand Up @@ -95,12 +93,12 @@ typedef enum {
*/
#define HAVE_ADC_RES_T
typedef enum {
ADC_RES_6BIT = 0, /**< ADC resolution: 6 bit */
ADC_RES_8BIT, /**< ADC resolution: 8 bit */
ADC_RES_10BIT, /**< ADC resolution: 10 bit */
ADC_RES_12BIT, /**< ADC resolution: 12 bit */
ADC_RES_14BIT, /**< ADC resolution: 14 bit */
ADC_RES_16BIT, /**< ADC resolution: 16 bit */
ADC_RES_6BIT = (0x4 << 17), /**< ADC resolution: 6 bit */
ADC_RES_8BIT = (0x2 << 17), /**< ADC resolution: 8 bit */
ADC_RES_10BIT = (0x0 << 17), /**< ADC resolution: 10 bit */
ADC_RES_12BIT = 1, /**< ADC resolution: 12 bit, no supported */
ADC_RES_14BIT = 2, /**< ADC resolution: 14 bit, no supported */
ADC_RES_16BIT = 3, /**< ADC resolution: 16 bit, no supported */
} adc_res_t;
/** @} */
#endif /* ndef DOXYGEN */
Expand Down
28 changes: 18 additions & 10 deletions cpu/lpc11u34/periph/adc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -24,8 +24,19 @@

#include "cpu.h"
#include "mutex.h"
#include "assert.h"
#include "periph/adc.h"

#define START_CMD (0x1 << 24)
#define DONE_BIT (0x1 << 31)
#define RES_MASK (0xf << 17)
#define SAMPLE_SHIFT (6)
#define SAMPLE_MASK (0x3ff)

/* we chose an ADC clock smaller or equal than but close to 4.5MHz (as proposed
* in the reference manual) */
#define CLK_DIV (((CLOCK_CORECLOCK / 45000000) & 0xff) << 8)

/**
* @brief Mutex to synchronize ADC access from different threads
*/
Expand Down Expand Up @@ -57,8 +68,6 @@ int adc_init(adc_t line)

prep();

/* ADC frequency : 3MHz */
LPC_ADC->CR = (15 << 8);
/* configure the connected pin */
pincfg = pincfg_reg(line);
/* Put the pin in its ADC alternate function */
Expand All @@ -80,23 +89,22 @@ int adc_sample(adc_t line, adc_res_t res)
{
int sample;

assert(line < ADC_NUMOF);

/* check if resolution is valid */
if (res < 0xff) {
if (res & ~(RES_MASK)) {
return -1;
}

/* prepare the device */
prep();

/* set resolution */
LPC_ADC->CR &= ~(0x7 << 17);
LPC_ADC->CR |= res;
/* Start a conversion */
LPC_ADC->CR |= (1 << line) | (1 << 24);
/* start conversion */
LPC_ADC->CR = ((1 << line) | CLK_DIV | res | START_CMD);
/* Wait for the end of the conversion */
while (!(LPC_ADC->DR[line] & (1 << 31))) {}
while (!(LPC_ADC->DR[line] & DONE_BIT)) {}
/* Read and return result */
sample = (LPC_ADC->DR[line] >> 6);
sample = ((LPC_ADC->DR[line] >> SAMPLE_SHIFT) & SAMPLE_MASK);

done();

Expand Down