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#include "project.h"
#define POT GPIO3
#define POT_PORT GPIOC
#define POT_CHANNEL ADC_CHANNEL13
#define VREF_CHANNEL ADC_CHANNEL17
#define ADC_TIMEOUT 1000
static enum {
WAIT_VREF,
WAIT_POT
} state = WAIT_VREF;
static uint32_t adc_stamp;
static uint16_t pot, vref;
uint8_t pot_brightness = 0x8;
static void start_conversion (uint8_t ch)
{
adc_stamp = ticks;
adc_set_regular_sequence (ADC1, 1, &ch);
adc_start_conversion_regular (ADC1);
}
static void calculate_and_set_brightness (void)
{
static uint32_t spot, svref;
uint32_t v;
/* dumb IIR with 16x gain */
spot *= 15;
spot >>= 4;
spot += pot ;
svref *= 15;
svref >>= 4;
svref += vref ;
if (svref > 65535) svref = 65535;
if (spot > 65535) spot = 65535;
v = spot << 16;
v /= svref;
v <<= 8;
v /= 12014; // vref is 1.2v FSD is 3.3v, 15 brightness levels so (65536 * (3.3/1.2) /15 )
v >>= 8;
if (v > 15) v = 15;
pot_brightness = v;
}
void adc_dispatch (void)
{
uint32_t now = ticks;
uint32_t ago;
ago = now - adc_stamp;
if (ago > ADC_TIMEOUT) {
adc_power_off (ADC1);
adc_power_on (ADC1);
state = WAIT_VREF;
start_conversion (VREF_CHANNEL);
return;
}
if (!adc_eoc (ADC1))
return;
switch (state) {
case WAIT_VREF:
vref = adc_read_regular (ADC1);
start_conversion (POT_CHANNEL);
state = WAIT_POT;
break;
case WAIT_POT:
pot = adc_read_regular (ADC1);
start_conversion (VREF_CHANNEL);
calculate_and_set_brightness();
/* fall through */
default:
state = WAIT_VREF;
}
}
void adc_init (void)
{
rcc_periph_clock_enable (RCC_ADC1);
MAP_ANALOG_INPUT (POT);
adc_power_off (ADC1);
adc_disable_scan_mode (ADC1);
adc_enable_temperature_sensor();
adc_set_single_conversion_mode (ADC1);
adc_enable_temperature_sensor(); /*Enables reference*/
adc_set_sample_time (ADC1, POT_CHANNEL, ADC_SMPR_SMP_480CYC);
adc_set_sample_time (ADC1, VREF_CHANNEL, ADC_SMPR_SMP_480CYC);
adc_enable_external_trigger_regular (ADC1, 0, ADC_CR2_EXTEN_DISABLED);
adc_set_right_aligned (ADC1);
adc_eoc_after_group (ADC1);
adc_power_on (ADC1);
adc_enable_temperature_sensor(); /*Enables reference*/
state = WAIT_VREF;
start_conversion (VREF_CHANNEL);
}
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