From fdb47b96e86924bf81852205b2b3078b8b21d040 Mon Sep 17 00:00:00 2001
From: Selene ToyKeeper
Date: Tue, 21 Nov 2023 02:52:00 -0700
Subject: got ADC voltage+temp working on avrdd... but broke all other
 builds/MCUs

This patch changes the ADC code to use two internal standard units, and
everything else must convert to these units:

- FSM Volts: centiVolts << 6  (range 0 to 10.24 V per cell)
- FSM Kelvin: Kelvin << 6  (range 0 to 1024 K)

UI-level voltage is still "Volts * 10", and temperature is still Celsius.

FSM expects functions to be provided, to convert from the hardware's
raw ADC measurements to these internal units:  `voltage_raw2cooked()`
and `temp_raw2cooked()`.  Defaults will be provided by arch/*.[ch] for
each MCU type, or the hwdef can make its own.

Anyway, gotta go fix all the other MCUs and builds now.  :(
---
 fsm/adc.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

(limited to 'fsm')

diff --git a/fsm/adc.c b/fsm/adc.c
index 13a76b6..73e282d 100644
--- a/fsm/adc.c
+++ b/fsm/adc.c
@@ -30,6 +30,7 @@ void adc_voltage_mode() {
 }
 
 
+#if 0
 #ifdef USE_VOLTAGE_DIVIDER
 static inline uint8_t calc_voltage_divider(uint16_t value) {
     // use 9.7 fixed-point to get sufficient precision
@@ -44,6 +45,7 @@ static inline uint8_t calc_voltage_divider(uint16_t value) {
     return result;
 }
 #endif
+#endif
 
 // Each full cycle runs ~2X per second with just voltage enabled,
 // or ~1X per second with voltage and temperature.
@@ -67,7 +69,6 @@ ISR(ADC_vect) {
 
         // update the latest value
         #ifdef MCU_ADC_RESULT_PER_TYPE
-            // thermal, convert ADC reading to left-aligned Kelvin
             if (channel) m = mcu_adc_result_temp();
             else m = mcu_adc_result_volts();
         #else
@@ -208,6 +209,19 @@ 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);
+
+    // calculate actual voltage: volts * 10
+    // TODO: should be (volts * 40) for extra precision
+    voltage = (measurement + VOLTAGE_FUDGE_FACTOR
+               #ifdef USE_VOLTAGE_CORRECTION
+                  + VOLT_CORR - 7
+               #endif
+               ) >> 1;
+
+    #if 0
     // values stair-step between intervals of 64, with random variations
     // of 1 or 2 in either direction, so if we chop off the last 6 bits
     // it'll flap between N and N-1...  but if we add half an interval,
@@ -231,6 +245,7 @@ static inline void ADC_voltage_handler() {
                #endif
                ) >> 1;
     #endif
+    #endif
 
     // if low, callback EV_voltage_low / EV_voltage_critical
     //         (but only if it has been more than N seconds since last call)
@@ -290,8 +305,14 @@ static inline void ADC_temperature_handler() {
     }
 
     // latest 16-bit ADC reading
-    uint16_t measurement = adc_smooth[1];
+    // convert raw ADC value to Kelvin << 6
+    // 0 .. 65535 = 0 K .. 1024 K
+    uint16_t measurement = temp_raw2cooked(adc_smooth[1]);
 
+    // (Kelvin << 6) to Celsius
+    temperature = (measurement>>6) + THERM_CAL_OFFSET + (int16_t)TH_CAL - 275;
+
+    #if 0
     // values stair-step between intervals of 64, with random variations
     // of 1 or 2 in either direction, so if we chop off the last 6 bits
     // it'll flap between N and N-1...  but if we add half an interval,
@@ -313,6 +334,12 @@ static inline void ADC_temperature_handler() {
     // external sensor
     temperature = EXTERN_TEMP_FORMULA(measurement>>1) + THERM_CAL_OFFSET + (int16_t)TH_CAL;
     #endif
+    #endif
+
+    // instead of (K << 6), use (K << 1) now
+    // TODO: use more precision, if it can be done without overflow in 16 bits
+    //       (and still work on attiny85 without increasing ROM size)
+    measurement = measurement >> 5;
 
     // how much has the temperature changed between now and a few seconds ago?
     int16_t diff;
-- 
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