From a87812f436e08b14a7cede83e30306d779774872 Mon Sep 17 00:00:00 2001
From: Selene ToyKeeper
Date: Mon, 25 Mar 2024 04:25:43 -0600
Subject: dammit, got alkaline detection half working and then my flashing
 adapter died (saving progress here so I can work on a different branch)

---
 hw/hank/emisar-d3aa/hwdef.c | 64 +++++++++++++++++++++++++++++++++++++++++++++
 hw/hank/emisar-d3aa/hwdef.h |  9 +++++++
 2 files changed, 73 insertions(+)

(limited to 'hw')

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
-- 
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