afterburner/aftb_vpp.h

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/*
* Variable voltage functions for Afterburner GAL project.
*
* 2024-02-02 Minor changes in varVppInit()
*/
#ifndef __AFTB_VPP_H__
#define __AFTB_VPP_H__
#include <EEPROM.h>
// ensure mcp4131 pot uses the right pins
#define POT_CS A3
#define POT_CLK A4
#define POT_DAT A5
#define VPP A0
#include "aftb_mcp4131.h"
#ifndef FAIL
#define FAIL 0
#define OK 1
#endif
#define ABS(X) ((X) < 0 ? -(X) : (X));
#define VPP_5V0 0xFF
#define VPP_9V0 0
#define VPP_9V5 1
#define VPP_10V0 2
#define VPP_10V5 3
#define VPP_11V0 4
#define VPP_11V5 5
#define VPP_12V0 6
#define VPP_12V5 7
#define VPP_13V0 8
#define VPP_13V5 9
#define VPP_14V0 10
#define VPP_14V5 11
#define VPP_15V0 12
#define VPP_15V5 13
#define VPP_16V0 14
#define VPP_16V5 15
#define MAX_WIPER 16
#define VPP_VERBOSE 0
#ifdef EXTERNAL
#define ANALOG_REF_EXTERNAL EXTERNAL
#else
#define ANALOG_REF_EXTERNAL AR_EXTERNAL
#endif
//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};
// VPP must ramp-up to prevent voltage spikes and possibly resetting arduino
// These values are for mcp4151 (for mcp4131 they are divided by 2)
#define varVppSetMax() varVppSetVppIndex(0x80); \
varVppSetVppIndex(0xE0); \
varVppSetVppIndex(0xF4); \
varVppSetVppIndex(0xFA); \
varVppSetVppIndex(0xFF);
#define varVppSetMin() varVppSetVppIndex(0x0);
uint8_t wiperStat = 0; //enabled / disabled
int8_t calOffset = 0; // VPP calibration offset: value 10 is 0.1V, value -10 is -0.1V
static void varVppReadCalib(void) {
uint8_t i;
//calibration not found
if (EEPROM.read(0) != 0xAF || EEPROM.read(1) != 0xCA) {
vppWiper[0] = 0;
Serial.println(F("No calibration data in EEPROM"));
return;
}
calOffset = (int8_t) EEPROM.read(2);
for (i = 0; i < MAX_WIPER; i++) {
vppWiper[i] = EEPROM.read(i + 3);
#if 0
Serial.print(F("Calib "));
Serial.print(i);
Serial.print(F(":"));
Serial.println(vppWiper[i]);
#endif
}
}
// internal use only - set the wiper value on the digital pot
static void varVppSetVppIndex(uint8_t value) {
uint8_t i;
#if VPP_VERBOSE
Serial.print(F("varSetVppIndex "));
Serial.println(value);
#endif
mcp4131_write(ADDR_WIPER, value);
#if VPP_PARANOID
i = mcp4131_read(ADDR_WIPER);
if (i != value) {
Serial.print(F("Error writing POT value. Expected:"));
Serial.print(value);
Serial.print(F(" Actual:"));
Serial.println(i);
}
#endif
if (value == 0) {
mcp4131_disableWiper();
wiperStat = 0;
} else if (wiperStat == 0) {
mcp4131_enableWiper();
wiperStat = 1;
}
}
//use by the app code - set the variable voltage
static void varVppSet(uint8_t value) {
uint8_t v;
int8_t inc;
if (value == VPP_5V0 || value >= MAX_WIPER) {
varVppSetVppIndex(0);
return;
}
#if VPP_VERBOSE
Serial.print(F("varSetVpp "));
Serial.print(value);
Serial.print(F(":"));
Serial.println(vppWiper[value]);
#endif
//ramp up to prevent massive voltage overshoots
v = vppWiper[value] / 3;
inc = v >> 2;
while (v < vppWiper[value]) {
varVppSetVppIndex(v);
v+= (inc << 1);
inc -= (inc >> 1);
if (inc < 2) {
inc = 2;
}
}
varVppSetVppIndex(vppWiper[value]);
}
// UNO R4/Minima - Renesas IC (significant ADC gain errors measured)
#ifdef AREF_IS_3V2
#define SAMPLE_CNT 16
#define SAMPLE_DIVIDER 8
#define SAMPLE_MULTIPLIER 25
// SAMPLE_SHIFT moves the ADC gain error up/down
#define SAMPLE_SHIFT -45;
//AVR based Arduinos (no ADC gain errors measured)
#else
#define SAMPLE_CNT 14
#define SAMPLE_DIVIDER 8
#define SAMPLE_MULTIPLIER 1
#define SAMPLE_OFFSET 5
#endif
static int16_t varVppMeasureVpp(int8_t printValue) {
int8_t i = 0;
uint16_t r1 = 0;
int16_t r2; //correction for ADC gain error
while (i++ < SAMPLE_CNT) {
r1 += analogRead(VPP);
}
r2 = (r1 / (SAMPLE_DIVIDER * SAMPLE_MULTIPLIER));
#ifdef SAMPLE_OFFSET
r1+= SAMPLE_OFFSET;
#endif
r1 /= SAMPLE_DIVIDER;
#ifdef SAMPLE_SHIFT
r2 += SAMPLE_SHIFT;
r1 += r2;
#endif
r1 += calOffset;
if (printValue) {
uint8_t a = r1%100;
Serial.print(r1/100);
Serial.print(F("."));
if (a < 10) {
Serial.print(F("0"));
}
#if 1
Serial.println(a);
#else
//debug - display the voltage skew value in r2
Serial.print(a);
Serial.println(F(", "));
Serial.println(r2);
#endif
}
return r1;
}
// Returns 1 on Success, 0 on Failure
static uint8_t varVppCalibrateVpp(void) {
uint8_t vppIndex = 0;
uint8_t i = 1;
int16_t v = 900; //starting at 9.00 V
int16_t r1 = 0;
int16_t r2;
int16_t minDif;
Serial.print(F("VPP calib. offset: "));
Serial.println(calOffset);
varVppSetVppIndex(1);
delay(300); //settle voltage
while (1) {
// reset the 'minimal difference' variable every time we search for a new index
minDif = 9000;
//the 'vppWiper' storage for tap indices is 8bit wide, therefore we must not use tap index 256.
while (i <= 0xFF) {
int16_t d1,d2;
varVppSetVppIndex(i);
delay(100); //let the voltage settle
r2 = varVppMeasureVpp(0);
// Sanity check: the previous voltage can't be higher than the voltage just measured
// because we are ramping up the voltage. Therefore it must be an ADC measurement
// glitch. In that case use the previous value as the measured one.
// This can happen at lower tap indices where the voltage differences are very small (like 0.01V).
if (r1 > r2) {
r2 = r1;
}
d1 = r1 - v;
d2 = r2 - v;
d1 = ABS(d1);
d2 = ABS(d2);
#if VPP_VERBOSE
Serial.print(i);
Serial.print(F(") r2="));
Serial.print(r2, DEC);
Serial.print(F(" d1="));
Serial.print(d1, DEC);
Serial.print(F(" d2="));
Serial.print(d2, DEC);
Serial.print(F(" md="));
Serial.println(minDif, DEC);
#endif
if (r2 <= 100) { // less than 1V ? Failure
r1 = FAIL;
goto ret;
}
if (d2 <= minDif) {
minDif = d2;
vppWiper[vppIndex] = i;
//check last value / voltage
if (i == 0xFF) {
if (v >= 1620 && v <= 1670) {
Serial.println(F("*Index for VPP 1650 is 255"));
r1 = OK;
goto ret;
}
r1 = FAIL;
goto ret;
}
} else {
i--;
minDif = 5000;
Serial.print(F("*Index for VPP "));
Serial.print(v);
Serial.print(F(" is "));
Serial.println(i);
break;
}
r1 = r2;
i++;
}
vppIndex++;
#if VPP_VERBOSE
Serial.print(F("vppIndex "));
Serial.println(vppIndex);
#endif
if (vppIndex >= MAX_WIPER) {
r1 = OK;
goto ret;
}
v += 50; //next voltage to search for is 0.5V higher
}
ret:
varVppSet(VPP_5V0);
return r1;
}
static void varVppStoreWiperCalib() {
uint8_t i = 0;
//sanity check
if (vppWiper[0] == 0) {
return;
}
//write Afterburner calibration header
EEPROM.update(0, 0xAF);
EEPROM.update(1, 0xCA);
EEPROM.update(2, (uint8_t) calOffset);
while (i < MAX_WIPER) {
EEPROM.update(3 + i, vppWiper[i]);
i++;
}
}
//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
analogRead(VPP); // Perform a dummy conversion referring to the datasheet
wiperStat = 0; //wiper disabled
mcp4131_init();
if (mcp4131_detect()) {
#if VPP_VERBOSE
Serial.print(mcp4131_detected ? F("MCP4131") : F("MCP4151"));
Serial.println(F(" POT found"));
#endif
return OK;
} else {
#if VPP_VERBOSE
Serial.println(F("POT not found"));
#endif
return FAIL;
}
}
//return 1 on success (VPP calibration appears correct), 0 on failure
static int8_t varVppCheckCalibration(void) {
int16_t v;
varVppReadCalib();
if (vppWiper[0] == 0) {
Serial.println(F("I: VPP not calibrated"));
return FAIL;
}
#if 0
// This shoots the VPP to 9V - in theory no GALs should have an issue with that voltage.
// Also, the On switch should be turned off, preventing VPP to reach the GAL pins.
// check actual voltage
varVppSet(VPP_9V0);
delay(200); //Settle voltage
v = varVppMeasureVpp(0);
varVppSet(VPP_5V0); //set VPP back to 5V
// lower voltages have a good resolution, so we can have a tight voltage check bounds
if (v < 890 || v > 910) {
Serial.print(F("ER: VPP voltage check of 9V failed. Expected 900, measured "));
Serial.println(v);
return FAIL;
}
#endif
return OK;
}
// only for VPP testing and debugging
static void varrVppTestRamp(void) {
uint8_t i = 1;
while (i < 256) {
varVppSetVppIndex(i);
delay(400);
Serial.println(i, DEC);
varVppMeasureVpp(1);
i++;
}
delay(2000);
varVppSetVppIndex(0);
}
static int8_t varVppCalibrate(void) {
#if 0
// only for testing and debugging
varrVppTestRamp();
return OK;
#endif
if (varVppCalibrateVpp()) {
varVppStoreWiperCalib();
} else {
Serial.println(F("ER: Wiper calibration failed"));
return FAIL;
}
return OK;
}
#endif