ADC voltage: battcheck 3 digits, fixed t1616, switched back to 8-bit internal volt unit

Before this branch, `voltage` was 6 bits: Volts * 10
A couple patches ago, I upgraded it to 16 bits: 65535 * Volts / 10.24
That costs too much extra ROM on attiny85 though, for extra precision
it doesn't even use... so I switched back to an 8-bit value.  It's still
more precise than before though: Volts * 40
... and battcheck displays an extra digit now, on devices with ROM for it.
... and battcheck waits a second to get a more accurate measurement
    before displaying the first value.  It has *much* less variation
    between first and later readings now.

Also:
- got t1616 builds working again (tested fc13 and thefreeman-boost-fwaa)
- upgraded t1616 voltage and temp to 12-bit (10 bits + 4x oversampling)
- removed expensive temp conversion from t1616 ADC interrupt
- recalibrated t1616 bogomips again; runs faster after interrupt fix
- increased t1616 internal VDD measurement resolution by 36% (1.5V Vref, not 1.1V)
- fixed sloppy setting of Vref bits

I still need to test / update other t1616 builds,
and fix all the t85 + t1634 code and build targets.

2 files changed, 31 insertions, 20 deletions

diff --git a/fsm/adc.c b/fsm/adc.c
index 73e282d..97dfc93 100644
--- a/fsm/adc.c
+++ b/fsm/adc.c
@@ -209,10 +209,16 @@ static inline void ADC_voltage_handler() {
     #endif
     else measurement = adc_smooth[0];
 
-    // convert raw ADC value to FSM voltage units: (V * 100) << 6
-    // 0 .. 65535 = 0.0V .. 10.24V
-    measurement = voltage_raw2cooked(measurement) / (10 << 5);
-
+    // convert raw ADC value to FSM voltage units: Volts * 40
+    // 0 .. 200 = 0.0V .. 5.0V
+    voltage = voltage_raw2cooked(measurement)
+              + (VOLTAGE_FUDGE_FACTOR << 1)
+              #ifdef USE_VOLTAGE_CORRECTION
+                 + ((VOLT_CORR - 7) << 1)
+              #endif
+              ;
+
+    /*
     // calculate actual voltage: volts * 10
     // TODO: should be (volts * 40) for extra precision
     voltage = (measurement + VOLTAGE_FUDGE_FACTOR
@@ -220,6 +226,7 @@ static inline void ADC_voltage_handler() {
                   + VOLT_CORR - 7
                #endif
                ) >> 1;
+    */
 
     #if 0
     // values stair-step between intervals of 64, with random variations
@@ -433,33 +440,37 @@ static inline void ADC_temperature_handler() {
 #ifdef USE_BATTCHECK
 #ifdef BATTCHECK_4bars
 PROGMEM const uint8_t voltage_blinks[] = {
-    30, 35, 38, 40, 42, 99,
+    4*30, 4*35, 4*38, 4*40, 4*42, 255,
 };
 #endif
 #ifdef BATTCHECK_6bars
 PROGMEM const uint8_t voltage_blinks[] = {
-    30, 34, 36, 38, 40, 41, 43, 99,
+    4*30, 4*34, 4*36, 4*38, 4*40, 4*41, 4*43, 255,
 };
 #endif
 #ifdef BATTCHECK_8bars
 PROGMEM const uint8_t voltage_blinks[] = {
-    30, 33, 35, 37, 38, 39, 40, 41, 42, 99,
+    4*30, 4*33, 4*35, 4*37, 4*38, 4*39, 4*40, 4*41, 4*42, 255,
 };
 #endif
 void battcheck() {
     #ifdef BATTCHECK_VpT
-    blink_num(voltage);
-    #else
-    uint8_t i;
-    for(i=0;
-        voltage >= pgm_read_byte(voltage_blinks + i);
-        i++) {}
-    #ifdef DONT_DELAY_AFTER_BATTCHECK
-    blink_digit(i);
+        blink_num(voltage / 4);
+        #ifdef USE_EXTRA_BATTCHECK_DIGIT
+            // 0 1 2 3 --> 0 2 5 7, representing x.x00 x.x25 x.x50 x.x75
+            blink_num(((voltage % 4)<<1) + ((voltage % 4)>>1));
+        #endif
     #else
-    if (blink_digit(i))
-        nice_delay_ms(1000);
-    #endif
+        uint8_t i;
+        for(i=0;
+            voltage >= pgm_read_byte(voltage_blinks + i);
+            i++) {}
+        #ifdef DONT_DELAY_AFTER_BATTCHECK
+            blink_digit(i);
+        #else
+            if (blink_digit(i))
+                nice_delay_ms(1000);
+        #endif
     #endif
 }
 #endif
diff --git a/fsm/adc.h b/fsm/adc.h
index 65d7d6c..0c0a9e5 100644
--- a/fsm/adc.h
+++ b/fsm/adc.h
@@ -17,11 +17,11 @@ volatile uint8_t adc_reset = 2;
 #endif
 // low-battery threshold in volts * 10
 #ifndef VOLTAGE_LOW
-#define VOLTAGE_LOW 29
+#define VOLTAGE_LOW (4*29)
 #endif
 // battery is low but not critical
 #ifndef VOLTAGE_RED
-#define VOLTAGE_RED 33
+#define VOLTAGE_RED (4*33)
 #endif
 // MCU sees voltage 0.X volts lower than actual, add X/2 to readings
 #ifndef VOLTAGE_FUDGE_FACTOR