dammit, got alkaline detection half working and then my flashing adapter died

(saving progress here so I can work on a different branch)

5 files changed, 91 insertions, 2 deletions

diff --git a/fsm/ramping.c b/fsm/ramping.c
index adc8acb..63ab399 100644
--- a/fsm/ramping.c
+++ b/fsm/ramping.c
@@ -57,6 +57,11 @@ inline void set_level_aux_rgb_leds(uint8_t level) {
 
 
 void set_level(uint8_t level) {
+    #ifdef USE_RAMP_LEVEL_HARD_LIMIT
+    if (level > ramp_level_hard_limit)
+        level = ramp_level_hard_limit;
+    #endif
+
     #ifdef USE_JUMP_START
     // maybe "jump start" the engine, if it's prone to slow starts
     // (pulse the output high for a moment to wake up the power regulator)
diff --git a/fsm/ramping.h b/fsm/ramping.h
index c4b7d48..6fe87fe 100644
--- a/fsm/ramping.h
+++ b/fsm/ramping.h
@@ -10,6 +10,9 @@
 uint8_t actual_level = 0;
 // the level used before actual
 uint8_t prev_level = 0;
+#ifdef USE_RAMP_LEVEL_HARD_LIMIT
+uint8_t ramp_level_hard_limit = RAMP_SIZE;
+#endif
 
 void set_level(uint8_t level);
 //void set_level_smooth(uint8_t level);
diff --git a/hw/hank/emisar-d3aa/hwdef.c b/hw/hank/emisar-d3aa/hwdef.c
index e2fd315..f6cf94e 100644
--- a/hw/hank/emisar-d3aa/hwdef.c
+++ b/hw/hank/emisar-d3aa/hwdef.c
@@ -4,6 +4,8 @@
 #pragma once
 
 #include "fsm/chan-rgbaux.c"
+#include "fsm/ramping.h"
+#include "ui/anduril/misc.h"
 
 void set_level_zero();
 
@@ -110,3 +112,65 @@ uint8_t voltage_raw2cooked(uint16_t measurement) {
 }
 #endif
 
+#ifdef USE_WEAK_BATTERY_PROTECTION
+uint8_t quick_volt_measurement() {
+    // take the average of a few samples
+    // (assumes the ADC is in voltage mode and running continuously)
+    uint16_t total = 0;
+    for (uint8_t i=0; i<8; i++) {
+        uint16_t m = adc_raw[0];
+        total += voltage_raw2cooked(m);
+        delay_zero();
+    }
+    uint8_t v = total / 8;
+    return v;
+}
+
+void detect_weak_battery() {
+    // guess at the cell strength with a load test...
+    // - measure voltage while LEDs off
+    // - measure again with LEDs on
+    // - determine how much to limit power
+    // - blink to indicate weak battery mode, if active
+
+    uint16_t resting, loaded;
+
+    set_level(0);
+    resting = quick_volt_measurement();
+
+    set_level(WEAK_BATTERY_CHECK_LEVEL);
+    loaded = quick_volt_measurement();
+    set_level(0);
+
+    int16_t diff = resting - loaded;
+    uint8_t extra_blinks = 0;
+
+    if (loaded <= DUAL_VOLTAGE_LOW_LOW) {
+        // weak or empty AA battery has a low limit
+        ramp_level_hard_limit = WEAK_BATTERY_LOWEST_LIMIT;
+        extra_blinks = 2;
+    } else if (loaded >= VOLTAGE_RED) {
+        // reasonably strong li-ion battery
+        ramp_level_hard_limit = WEAK_BATTERY_HIGHEST_LIMIT;
+    } else if (diff <= (-5 * 4)) {
+        // marginal battery, dropped a lot under mild load
+        ramp_level_hard_limit = WEAK_BATTERY_MEDIUM_LIMIT;
+        extra_blinks = 1;
+    }
+
+    for (uint8_t i=0; i<extra_blinks; i++) {
+        delay_4ms(300/4);
+        blink_once();
+    }
+
+    voltage = resting;
+    battcheck();
+
+    voltage = loaded;
+    battcheck();
+
+    //if (diff < 0)
+    //    blink_num(-diff);
+}
+#endif
+
diff --git a/hw/hank/emisar-d3aa/hwdef.h b/hw/hank/emisar-d3aa/hwdef.h
index 56dd061..1e677b6 100644
--- a/hw/hank/emisar-d3aa/hwdef.h
+++ b/hw/hank/emisar-d3aa/hwdef.h
@@ -114,6 +114,15 @@ enum CHANNEL_MODES {
     #define USE_VOLTAGE_VDDIO2
 #endif
 
+// Alkaline AA can't handle the power this light wants,
+// so try to detect it and limit the maximum power
+#define USE_RAMP_LEVEL_HARD_LIMIT
+#define USE_WEAK_BATTERY_PROTECTION
+#define WEAK_BATTERY_HIGHEST_LIMIT  RAMP_SIZE
+#define WEAK_BATTERY_MEDIUM_LIMIT   (RAMP_SIZE*2/3)
+#define WEAK_BATTERY_LOWEST_LIMIT   (RAMP_SIZE*1/3)
+#define WEAK_BATTERY_CHECK_LEVEL    (RAMP_SIZE*2/3)
+
 // average drop across diode on this hardware
 #ifndef VOLTAGE_FUDGE_FACTOR
 #define VOLTAGE_FUDGE_FACTOR 0  // using a PFET so no appreciable drop
diff --git a/ui/anduril/anduril.c b/ui/anduril/anduril.c
index 1cdb8d0..f50f8d2 100644
--- a/ui/anduril/anduril.c
+++ b/ui/anduril/anduril.c
@@ -225,8 +225,16 @@ void setup() {
 
         // regular e-switch light, no hard clicky power button
 
-        // blink at power-on to let user know power is connected
-        blink_once();
+        #ifdef USE_WEAK_BATTERY_PROTECTION
+            // try to measure the battery strength
+            // (must be done *before* factory reset,
+            //  because reset tries to use full power,
+            //  and a weak battery can't do that)
+            detect_weak_battery();
+        #else
+            // blink at power-on to let user know power is connected
+            blink_once();
+        #endif
 
         #ifdef USE_FACTORY_RESET
         if (button_is_pressed())