1 files changed, 29 insertions, 8 deletions
diff --git a/sw/picardy/src/main.rs b/sw/picardy/src/main.rs
index a6a3e4a..22b894b 100644
--- a/sw/picardy/src/main.rs
+++ b/sw/picardy/src/main.rs
@@ -292,14 +292,8 @@ fn main() -> ! {
         }
         previous_vfo = vfo;
 
-        let s_meter_value: u16 = adc2.read(&mut s_meter).unwrap();
-
-        // Avoid 0 because of log10
-        let s_meter_value = f32::from(if s_meter_value == 0 { 1 } else { s_meter_value });
-
-        // ADC is 12-bit, convert to dB full-scale
-        let s_meter_value = 10f32 * log10f::log10f(f32::from(s_meter_value) / 4092f32);
-        let s_meter_value = s_meter_value as i32;
+        let s_meter_adc_value: u16 = adc2.read(&mut s_meter).unwrap();
+        let s_meter_value = s_meter_from_adc(s_meter_adc_value);
         let t_now = ticks_now();
         if last_s_meter_update_time + 10 < t_now {
             update_disp_required = s_meter_value != last_s_meter_value;
@@ -322,6 +316,33 @@ fn main() -> ! {
     }
 }
 
+fn s_meter_from_adc(adc : u16) -> u8 {
+    // Avoid 0 because of log10
+    let adc = f32::from(if adc == 0 { 1 } else { adc });
+    // ADC is 12-bit, convert to dB full-scale
+    let adc_db = 10f32 * log10f::log10f(adc / 4092f32);
+
+    /* Hand-calibrated lookup table */
+    if adc_db <= -35f32 {
+        1
+    }
+    else if adc_db <= -20f32 {
+        4
+    }
+    else if adc_db <= -12f32 {
+        5
+    }
+    else if adc_db <= -8f32 {
+        6
+    }
+    else if adc_db <= -7f32 {
+        7
+    }
+    else {
+        9
+    }
+}
+
 #[interrupt]
 fn TIM2() {
     let timer = unsafe { &mut *CLOCK_TIMER.as_mut_ptr() };