1 files changed, 79 insertions, 0 deletions
diff --git a/stm32/app/pressure.c b/stm32/app/pressure.c
new file mode 100644
index 0000000..6b90d93
--- /dev/null
+++ b/stm32/app/pressure.c
@@ -0,0 +1,79 @@
+#include "project.h"
+
+#define PRESSURE      GPIO0
+#define PRESSURE_PORT     GPIOA
+#define PRESSURE_CHANNEL  ADC_CHANNEL0
+#define VREF_CHANNEL ADC_CHANNEL17
+
+static unsigned poke;
+
+static int pressure;
+
+uint16_t pressure_ch (void)
+{
+  return pressure;
+}
+
+
+
+
+void pressure_tick (void)
+{
+  static unsigned ticker;
+
+  ticker++;
+
+  if (ticker < MS_TO_TICKS (2500))
+    return;
+
+  ticker = 0;
+  poke = 1;
+
+}
+
+
+
+
+void pressure_dispatch (void)
+{
+  int v, r;
+
+  if (!poke) return;
+
+  poke = 0;
+
+  if (adc_calibrate()) {
+    pressure = 0;
+    return;
+  }
+
+  v = adc_convert (PRESSURE_CHANNEL);
+  r = adc_convert (VREF_CHANNEL);
+
+
+  /* r is 1.25 volts, transducer is 0.5V -> 0 psi 4.5V -> 100psi  */
+  /* 100psi is 6.8947573 bar, and we want 256ths of bar */
+
+  if (!r) {
+    pressure = 0;
+    return;
+  }
+
+  pressure = ((v * 552) / r) - 221;
+
+  if (pressure < 0) pressure = 0;
+
+  printf ("QP: %d %d %d\r\n", v, r, (pressure * 100) / 256);
+
+}
+
+
+
+void pressure_init (void)
+{
+  MAP_ANALOG (PRESSURE);
+}
+
+
+
+