1 files changed, 137 insertions, 0 deletions
diff --git a/app/adc.c b/app/adc.c
new file mode 100644
index 0000000..821bac9
--- /dev/null
+++ b/app/adc.c
@@ -0,0 +1,137 @@
+#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_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_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);
+}
+