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.  :(
---
 hw/thefreeman/avr32dd20-devkit/hwdef.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'hw/thefreeman/avr32dd20-devkit/hwdef.c')

diff --git a/hw/thefreeman/avr32dd20-devkit/hwdef.c b/hw/thefreeman/avr32dd20-devkit/hwdef.c
index e5b347f..133baca 100644
--- a/hw/thefreeman/avr32dd20-devkit/hwdef.c
+++ b/hw/thefreeman/avr32dd20-devkit/hwdef.c
@@ -103,3 +103,16 @@ bool gradual_tick_main(uint8_t gt) {
     return false;  // not done yet
 }
 
+
+uint16_t voltage_raw2cooked(uint16_t measurement) {
+    // In : 65535 * BATTLVL pin / 1.024 Vref
+    // Out: 65535 * (Vbat / 10) / 1.024V  (i.e. FSM Volt units)
+    // BATTLVL = Vbat * (100.0/(330+100)) = Vbat / 4.3
+    // So, Out = In * 4.3 / 10.24
+    // (plus 1.5% based on measured hardware)
+    // (plus a fudge factor of +0.04V to round up to nearest 1/10th Volt)
+    uint16_t result = ((uint32_t)measurement * 436 / 1024)
+                    + (65535 * 4 / 1024);
+    return result;
+}
+
-- 
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