From 2e88c0324dcc4bfc297f1cbd36a73cfc45884e89 Mon Sep 17 00:00:00 2001
From: HubertH <51236138+hubertushirsch@users.noreply.github.com>
Date: Wed, 14 Feb 2024 22:58:19 +0100
Subject: [PATCH] Update aftb_vpp.h for new VPP measurement

---
 aftb_vpp.h | 44 +++++++++++++++++++++++++++++++++-----------
 1 file changed, 33 insertions(+), 11 deletions(-)

diff --git a/aftb_vpp.h b/aftb_vpp.h
index 519f4f6..857944b 100644
--- a/aftb_vpp.h
+++ b/aftb_vpp.h
@@ -2,6 +2,7 @@
  * Variable voltage functions for Afterburner GAL project.
  * 
  * 2024-02-02 Minor changes in varVppInit()
+ * 2024-02-14 Redesign of VPP measurement (function varVppMeasureVpp())
  */
 #ifndef __AFTB_VPP_H__
 #define __AFTB_VPP_H__
@@ -15,6 +16,7 @@
 #define VPP      A0
 
 #include "aftb_mcp4131.h"
+#include "aftb_adcparms.h"
 #ifndef FAIL
 #define FAIL 0
 #define OK 1
@@ -41,19 +43,14 @@
 
 #define MAX_WIPER 16
 
-#define VPP_VERBOSE 0
-
-#ifdef EXTERNAL
-#define ANALOG_REF_EXTERNAL EXTERNAL
-#else
-#define ANALOG_REF_EXTERNAL AR_EXTERNAL
-#endif
+#define VPP_VERBOSE 1
 
+/* No longer necessary due to new measurement algorithm
 //UNO R4 Minima or Wifi (Aref internally pulled down by 130kOhm, AVR Uno R3 pulled down by 32kOhm)
 #ifdef _RENESAS_RA_
 #define AREF_IS_3V2
 #endif
-
+*/
 //pot wiper indices for the voltages 
 uint8_t vppWiper[MAX_WIPER] = {0};
 
@@ -79,7 +76,7 @@ static void varVppReadCalib(void) {
     calOffset = (int8_t) EEPROM.read(2);
     for (i = 0; i < MAX_WIPER; i++) {
         vppWiper[i] = EEPROM.read(i + 3);
-#if 0        
+#if 1        
         Serial.print(F("Calib "));
         Serial.print(i);
         Serial.print(F(":"));
@@ -149,6 +146,31 @@ static void varVppSet(uint8_t value) {
     varVppSetVppIndex(vppWiper[value]);
 }
 
+// New VPP measurement algorithm
+#define MCOUNT (14)     // Number of added measurements as integer
+#define ADCRES (10)     // Analog Read Resolution in bits as integer
+
+static int16_t varVppMeasureVpp(int8_t printValue) {
+    int adcsum = 0;     // Sum MCOUNT measurements here
+    int loops = 0;      // Counter for measure loop
+    float vpp;          // Vpp result as float
+    // Precalculate constant parts of the formula
+    float divisor = ADC_R6 * float(1 << ADCRES);
+    float dividend = VREF * (ADC_R5 + ADC_R6);
+
+    // Measure MCOUNT times and add results
+    do {
+        adcsum += analogRead(VPP);      // Sum MCOUNT measurements here
+    } while (++loops < MCOUNT);
+    // Now calculate the VPP
+    vpp = (float(adcsum) * dividend) / divisor / float(MCOUNT);
+    vpp += float(calOffset) / 100.0;
+    if (printValue) {
+        Serial.println(vpp);
+    }
+    return int16_t(vpp * 100.0);
+}
+/* No longer necessary due to new measurement algorithm
 // UNO R4/Minima - Renesas IC (significant ADC gain errors measured)
 #ifdef AREF_IS_3V2
 #define SAMPLE_CNT 16
@@ -201,7 +223,7 @@ static int16_t varVppMeasureVpp(int8_t printValue) {
     }
     return r1;
 }
-
+*/
 // Returns 1 on Success, 0 on Failure
 static uint8_t varVppCalibrateVpp(void) {
     uint8_t vppIndex = 0;
@@ -305,7 +327,7 @@ static void varVppStoreWiperCalib() {
 
 //return 1 on success (variable VPP functionality present), 0 on failure (VPP not detected on board)
 static int8_t varVppInit(void) {
-    analogReference(ANALOG_REF_EXTERNAL); //use 3V3 external reference
+    analogReference(AREF_SOURCE);  //use analog reference depending on settings in aftp_adcparms.h
     analogRead(VPP);            // Perform a dummy conversion referring to the datasheet
 
     wiperStat = 0; //wiper disabled