Jon Z
Controls both heat and pump pressure based on a temperature probe and a scale- ie, it does temperature and flow profiling. Should work with any vibratory pump machine.
Dependencies: Adafruit_RTCLib FastPWM TSI mbed
Diff: main.cpp
- Revision:
- 4:3d661b485d59
- Parent:
- 3:eb60e36b03f6
- Child:
- 5:0393adfdd439
--- a/main.cpp Thu Aug 29 14:55:52 2013 +0000
+++ b/main.cpp Wed Oct 02 13:38:23 2013 +0000
@@ -2,68 +2,88 @@
// Program to control espresso maker boiler temperatures
// Similar to multiple PID control (pre-brew, brew and steam),
// but uses a flexible open and closed loop table during brew
-// Used with a Gaggia Classic, FreeScale FRDM-KL25Z computer, PT1000 RTD, heater
+// Used with a Gaggia Classic, FreeScale FRDM-KL25Z computer, PT1000 RTD, SSR
+// Can also control the pump
// See www.coffeegeeks.com for discussion
// Jon Zeeff, 2013
// Public Domain
-// PT1000 RTD ohms (use Google to find a full table)
-// 1360 ohms = 94C
+// PT1000 RTD ohms (use Google to find a full table, remember to add offset)
+// 1362 ohms = 94C
+// 1374 ohms = 97C
// 1000 ohms = too cold (0C)
// 1520 ohms = too hot (136C)
-// note: assume a 2.2K divider resistor, a PT1000 RTD and a 16 bit A/D result
+// note: assume a precise 2.2K divider resistor, a PT1000 RTD and a 16 bit A/D result
// use this formula: A/D = (RTD_OHMS/(RTD_OHMS+2200)) * 65536
// desired A/D value for boiler temp while idling
-// note: there is usually some offset between boiler wall temp sensors and actual water temp
-#define TARGET_TEMP 25440 // CHANGE THIS
+// note: there is usually some offset between boiler wall temp sensors and actual water temp (10-15C?)
+#define TARGET_OHMS 1400 // Desired PT1000 RTD Ohms - CHANGE THIS
-// Table of adjustments (degrees C) to TARGET_TEMP vs time (seconds) into brew cycle (including preheat period)
+// Table of adjustments (degrees C) to TARGET_TEMP and heat vs time (seconds) into brew cycle (including preheat period)
// The idea is that extra heat is needed as cool water comes into the boiler during brew.
// Extra heat is provided by a higher than normal boiler wall temp.
// NOTE: the fractional portion of the value is used as the PWM value to be applied if more heat is needed.
// This can prevent overshoot.
// Example: 5.3 means that the boiler wall should be 5 degrees C above normal at this time point. If not, apply 30% power.
// Example: 99.99 means (roughly) that the heater should be completely on for the 1 second period
-// Note: heat takes at least 4 seconds before it is seen by the sensor
+// Note: heat on a Gaggia Classic takes about 4 seconds before it is seen by the sensor
+
+#define BREW_TIME 44 // max brew time
+#define BREW_PREHEAT 6 // max preheat time
-const double table[40] = {
- // preheat up to 10 seconds
- 0.0,0.0,0.0,0.0,0.0,0.0,0.0,99.9,99.9,99.20, // CHANGE THIS
+const double table[BREW_TIME+BREW_PREHEAT] = {
+ // preheat up to 6 seconds
+ 0,0,0,0,99.99,99.99, // CHANGE THIS
// brewing (pump is on) up to 30 seconds
- 99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20, // CHANGE THIS
- 99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,0,0,0,0 // CHANGE THIS
+ 0,0,0,0,0,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.40,99.35,99.35, // CHANGE THIS
+ 99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35, // CHANGE THIS
+ 99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35,99.35
};
-const double pump_table[40] = {
+// pump power over time for flush or preinfusion or pressure profiling
+const double pump_table[BREW_TIME+BREW_PREHEAT] = {
// during pre-brew period
- 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0, // CHANGE THIS
+ 0,0,0,0,.80,.80, // CHANGE THIS
// brewing up to 30 seconds
- 0.0,0.0,99.99,99.99,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20, // CHANGE THIS
- 99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,99.20,0,0,0,0 // CHANGE THIS
+ .85,.90,1.0,0,0,0,0,0,.80,1.0,1.0,1.0,1.0,1.0,1.0,1.0, // CHANGE THIS
+ 1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0, // CHANGE THIS
+ .85,.85,.85,.85,.85,.85,.85,.85,.85,.85
+};
+
+// desired total weight of espresso over brew period in grams
+const int scale_table[BREW_TIME+BREW_PREHEAT] = {
+ 2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,
+ 60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60,60
};
// these probably don't need to be changed if you are using a Gaggia Classic
+#define AD_PER_DEGREE 43 // how many A/D counts equal a 1 degree C change
+#define AD_PER_GRAM 76.75 // how many A/D count equal 1 gram of weight
#define CLOSE 60 // how close in A/D value before switching to learned value control
-#define GAIN .01 // how fast to adjust
+#define GAIN .01 // how fast to adjust (eg 1% percent per 2.7s control period)
#define INITIAL_POWER .03 // initial guess for steady state heater power needed (try .03 = 3%)
#define MIN_TEMP 21000 // below this is an error
-#define MAX_TEMP 29500 // above this is an error
+#define MAX_TEMP 29700 // above this is an error
#define STEAM_TEMP 28000 // boiler temp while steaming
-#define ROOM_TEMP 22000 // A/D value at standard ambient room temp
-#define MAX_ROOM_TEMP 22500 // above this means ambient isn't valid
-#define SLEEP_TIME 7200 // turn off heat after this many seconds
-#define BREW_TIME 30 // max brew time
-#define BREW_PREHEAT 10 // max preheat time
-#define AD_PER_DEGREE 44 // how many A/D counts equal a 1 degree C change
+#define ROOM_TEMP 21707 // A/D value at standard ambient room temp 23C
+#define MAX_ROOM_TEMP (ROOM_TEMP + (10 * AD_PER_DEGREE)) // above this means ambient isn't valid
+#define SLEEP_PERIOD (3*3600) // turn off heat after this many seconds
+#define WAKEUP_TIME 12 // time in 0-23 hours, GMT to wake up. 99 to disable. Example: 12 for noon GMT
+
+#define TARGET_TEMP ((TARGET_OHMS*65536)/(TARGET_OHMS+2200)) // how hot the boiler should be in A/D
#define debug if (1) printf // use if (1) or if (0)
#include "mbed.h"
#include "TSISensor.h" // touch sensor
#include "DS1307.h" // real-time clock
#include "FastPWM.h" // better PWM routine for pump control
-
+
+#define BOILER 0
+#define GROUP 1
+#define SCALE 2
+
#define OFF 0
#define RED 1
#define GREEN 2
@@ -76,65 +96,74 @@
#define ON 1
#define OFF 0
+// pin assignments
DigitalOut heater(PTD7); // Solid State Relay - PTD6&7 have high drive capability
FastPWM pump(PTD4); // Solid State Relay - PTD4 can do PWM @ 10K hz
-AnalogIn boiler(PTE20); // A/D converter reads temperature on boiler
-AnalogIn group(PTE22); // A/D for group basket temp
DigitalOut led_green(LED_GREEN);
-I2C gI2c(PTE0, PTE1); // SDA, SCL - use pullups
+I2C gI2c(PTE0, PTE1); // SDA, SCL - use pullups somewhere
RtcDs1307 rtclock(gI2c); // DS1307 is a real time clock chip
Serial pc(USBTX, USBRX); // Serial to pc connection
-
+TSISensor tsi; // used as a brew start button
+AnalogIn scale(PTC2); // A/D converter reads scale
+
void brew(void);
void led_color(int color);
-unsigned read_temp(AnalogIn adc);
+unsigned read_temp(int device);
+unsigned read_ad(AnalogIn adc);
void steam(int seconds);
unsigned ambient_temp; // room or water tank temp (startup)
double heat = INITIAL_POWER; // initial fractional heat needed while idle
-unsigned boiler_log[40]; // record boiler temp during brew
-unsigned group_log[40]; // record basket temp during brew
-
+unsigned boiler_log[BREW_TIME+BREW_PREHEAT]; // record boiler temp during brew
+unsigned group_log[BREW_TIME+BREW_PREHEAT]; // record basket temp during brew
+int scale_log[BREW_TIME+BREW_PREHEAT]; // record weight during brew
int main() // start of program
{
time_t prev_time = 0;
- TSISensor tsi; // used as a brew start button
- ambient_temp = read_temp(boiler); // save temp on startup
+
+ led_color(OFF);
+
+ wait(1); // let settle
+ ambient_temp = read_temp(BOILER); // save temp on startup
- set_time(0); // start clock at zero
#if 0
- DateTime dt = gRtc.now();
+ DateTime compiled(__DATE__, __TIME__); // to set RT clock initially
+ rtclock.adjust(compiled);
+#endif
+ DateTime dt = rtclock.now(); // check clock value
+ debug("RTC = %u/%u/%02u %2u:%02u:%02u\r\n"
+ ,dt.month(),dt.day(),dt.year()
+ ,dt.hour(),dt.minute(),dt.second());
+ set_time(0); // set active clock
- debug("%u/%u/%02u %2u:%02u:%02u\r\n"
- ,dt.month(),dt.day(),dt.year()
- ,dt.hour(),dt.minute(),dt.second());
-#endif
- debug("starting A/D value/temp = %u\r\n",ambient_temp);
-
- pump.period_ms(500); // period of PWM signal
- //pump = 100; // duty cycle. For DC, use 6 msec pulses
-
+ debug("starting A/D value/temp = %u %u\r\n",ambient_temp,read_temp(GROUP));
+
+ pump = 0; // duty cycle.
+ pump.period_us(410); // period of PWM signal in us
+
if (pc.readable()) // clear any data on serial port
- pc.getc();
-
+ pc.getc();
+
if (ambient_temp < MAX_ROOM_TEMP)
- steam(180); // do accelerated warmup by overheating
+ steam(5 * 60); // do accelerated warmup by overheating for awhile
// loop forever, controlling boiler temperature
for (;;) {
// read temp from A/D
// note: in A/D counts, not degrees
- unsigned temp = read_temp(boiler);
+ unsigned temp = read_temp(BOILER);
// bang/bang when far away, PWM to learned value when close
if (temp > TARGET_TEMP + CLOSE) {
heater = OFF; // turn off heater
led_color(GREEN); // set LED to green
+ wait(.17);
} else if (temp < TARGET_TEMP - CLOSE) {
heater = ON; // turn on heater
led_color(RED); // set LED to red
+ wait(.17);
} else { // close to target temp
// learning mode - adjust heat, the fraction of time power should be on
@@ -152,44 +181,58 @@
} // if
// the user must press a button 10 seconds prior to brewing to start preheat
- if (tsi.readPercentage() > .5)
+ if (tsi.readPercentage() > .5) {
brew();
-
+ set_time(0); // stay awake for awhile more
+ }
+
// if they signaled for steam
- if (tsi.readPercentage() > .2 && tsi.readPercentage() < .5)
- steam(120);
-
- if (pc.readable()){ // Check if data is available on serial port.
- pc.getc();
- // debug, print out temp log
+ //if (tsi.readPercentage() > .1 && tsi.readPercentage() < .5)
+ // steam(120);
+
+ if (pc.readable()) { // Check if data is available on serial port.
+ pc.getc();
+ // debug, print out brew temp log
int i;
- for (i = 0; i < 40; ++i)
- printf("log %d: %u %u\r\n",i,boiler_log[i],group_log[i]);
+ for (i = 0; i < BREW_TIME+BREW_PREHEAT; ++i)
+ printf("log %d: %u %u %d\r\n",i,boiler_log[i],group_log[i],scale_log[i]);
} // if
-
- // check for idle shutdown, sleep till tomorrow if it occurs
- if (time(NULL) > SLEEP_TIME) { // save power
- static time_t wakeup_time = (24 * 60 * 60) - (20 * 60); // 24 hours minus 20 min
- heater = OFF; // turn off heater
+ // check for idle shutdown, sleep till tomorrow am if it occurs
+ if (time(NULL) > SLEEP_PERIOD) { // save power
+ heater = OFF; // turn off heater
led_color(OFF);
printf("sleep\r\n");
- while (time(NULL) < wakeup_time) // wait till tomorrow
- wait(1);
- set_time(0); // clock runs zero to 24 hours
- wakeup_time = (24 * 60 * 60); // no 20 min offset needed now
- ambient_temp = read_temp(boiler); // save temp on startup
- }
+
+ for (;;) { // loop till wakeup in the morning
+ DateTime dt;
+
+ if (pc.readable()) // user wakeup
+ break;
+
+ dt = rtclock.now(); // read real time clock
+ if (dt.hour() == WAKEUP_TIME && dt.minute() == 0) // GMT time to wake up
+ break;
+
+ wait(30);
+ } // for
+
+ set_time(0); // reset active timer
+ debug("exit idle\r\n");
+ ambient_temp = read_temp(BOILER); // save temp on startup
+ } // if
// check for errors (incorrect boiler temp can be dangerous)
- if (temp > MAX_TEMP || temp < MIN_TEMP) {
- heater = OFF; // turn off heater
- led_color(YELLOW); // set LED to indicate error
+ while (temp > MAX_TEMP || temp < MIN_TEMP) {
+ heater = OFF; // turn off heater
+ led_color(YELLOW); // set LED to indicate error
debug("error A/D = %u\r\n",temp);
- for (;;); // reset needed to exit this
+ wait(60);
+ temp = read_temp(BOILER);
}
- if (time(NULL) > prev_time) debug("A/D value = %u %u, heat = %F\r\n",temp,read_temp(group),heat); // once per second
+ if (time(NULL) > prev_time)
+ debug("A/D value = %u %u, heat = %F, scale = %u\r\n",temp,read_temp(GROUP),heat,read_ad(scale)); // once per second
prev_time = time(NULL);
} // for (;;)
@@ -199,62 +242,85 @@
//=================================================================
// This subroutine is called when the button is pressed, 10 seconds
-// before the pump is started. It does both open loop and closed
+// before the pump is started. It does both open loop and closed
// loop PWM power/heat control.
//=================================================================
void brew(void)
{
- unsigned start_time = time(NULL);
-
double adjust = 1; // default is no adjustment
// adjust for higher or lower tank temp (assumed to be equal to ambient at startup)
// add in "heat"??
//if (ambient_temp < MAX_ROOM_TEMP) // sanity check
// adjust = (double)(ROOM_TEMP - TARGET_TEMP) / (double)(ambient_temp - TARGET_TEMP);
-
- debug("preheat/brew start, adjust = %F\r\n", adjust);
+
led_color(WHITE);
-
- unsigned prev_brew_time = 999;
- unsigned brew_time;
+
+ unsigned brew_time; // in seconds
double pwm;
+ unsigned temp;
+ unsigned scale_zero = read_ad(scale);
+ int grams;
- for (;;) {
- brew_time = time(NULL) - start_time; // seconds into cycle
-
- if (brew_time >= BREW_PREHEAT + BREW_TIME)
- break; // brew is done
+ debug("preheat/brew start, adjust = %F, zero = %u\r\n", adjust,scale_zero);
- if (brew_time == BREW_PREHEAT)
+ for (brew_time = 0; brew_time < BREW_PREHEAT + BREW_TIME; ++brew_time) { // loop until end of brew
+
+ if (brew_time == BREW_PREHEAT) {
led_color(BLUE); // set LED color to blue for start brew/pump now
+ }
- //pump = pump_table[brew_time]; // duty cycle
+ pump = pump_table[brew_time]; // duty cycle or on/off of pump for this period
+
+ pwm = table[brew_time] - (int)table[brew_time]; // decimal part only
- pwm = table[brew_time] - (int)table[brew_time]; // decimal part only
+ temp = read_temp(BOILER);
// if too cold, apply the PWM value, if too hot, do nothing
- if (read_temp(boiler) < (TARGET_TEMP + (table[brew_time] * AD_PER_DEGREE)) * adjust) {
- if (pwm > 0) {
- heater = ON;
- wait(pwm/2);
- heater = OFF;
- wait((1 - pwm)/2);
- }
- } // if PWM
+ if (temp < (TARGET_TEMP + (table[brew_time] * AD_PER_DEGREE)) * adjust) {
+ if (pwm > 0.0 && pwm <= 1.0) {
+ heater = ON;
+ wait(pwm);
+ heater = OFF;
+ pwm = 1 - pwm;
+ if (pwm > 0.0 && pwm <= 1.0)
+ wait(pwm);
+ } else
+ wait(1.0);
+ } else
+ wait(1.0);
- if (brew_time != prev_brew_time){ // every second
- group_log[brew_time] = read_temp(group); // record group temp
- boiler_log[brew_time] = read_temp(boiler); // record boiler temp
- debug("target temp %u = %F, temp = %u %u\r\n",brew_time,table[brew_time],read_temp(boiler),read_temp(group));
- prev_brew_time = brew_time;
- }
+ group_log[brew_time] = read_temp(GROUP); // record group temp
+ boiler_log[brew_time] = temp; // record boiler temp
+ grams = ((double)read_ad(scale) - scale_zero) / AD_PER_GRAM;
+ scale_log[brew_time] = grams;
+
+ if (grams < 2) // scale clock only starts when it hits two grams
+ scale_time = 0;
+ else
+ ++scale_time;
+
+ //if (grams > scale_table[scale_time])
+ //else
+
+ //debug("target temp %u = %F, temp = %u %u\r\n",brew_time,table[brew_time],read_temp(BOILER),read_temp(GROUP));
+
+ // early exit if final weight reached
+ if (grams >= scale_table[BREW_TIME+BREW_PREHEAT-1])
+ break;
+
+ // early exit based on user input
+ if (tsi.readPercentage() > .1 && tsi.readPercentage() < .5)
+ break;
} // for
+ // shut down
+ led_color(OFF);
debug("brew done\r\n");
-
+ pump = OFF;
+ heater = OFF;
} // brew()
//===========================================================
@@ -268,13 +334,17 @@
debug("steam start, time = %d\r\n", seconds);
while (time(NULL) - start_time < seconds) {
- if (read_temp(boiler) > STEAM_TEMP) {
- heater = OFF; // turn off heater
+ if (read_temp(BOILER) > STEAM_TEMP) {
+ heater = OFF; // turn off heater
led_color(AQUA); // set LED to aqua
} else {
- heater = ON; // turn on heater
+ heater = ON; // turn on heater
led_color(PINK); // set LED to pink
}
+
+ if (tsi.readPercentage() > .5) // abort steam
+ break;
+
} // while
heater = OFF; // turn off
@@ -323,32 +393,84 @@
} // led_color()
+#if 1
+// reduce noise by making unused A/D into digital outs
+DigitalOut x1(PTB0);
+DigitalOut x2(PTB1);
+DigitalOut x3(PTB2);
+DigitalOut x4(PTB3);
+DigitalOut x5(PTE21);
+DigitalOut x6(PTE23);
+DigitalOut x7(PTD5);
+DigitalOut x8(PTD6);
+DigitalOut x9(PTD1);
+DigitalOut x10(PTC0);
+#endif
+
//=======================================
-// read A/D value from RTD
-// median and average for accuracy
+// A/D routines
//=======================================
-unsigned read_temp(AnalogIn adc)
+DigitalOut ad_power(PTB9); // used to turn on/off power to resistors
+
+AnalogIn boiler(PTE20); // A/D converter reads temperature on boiler
+AnalogIn group(PTE22); // A/D for group basket temp
+AnalogIn vref(PTE29); // A/D for A/D power supply (ad_power)
+
+
+unsigned read_ad(AnalogIn adc)
{
uint32_t sum=0;
int i;
+
+ adc.read_u16(); // throw away one
+
+ #define COUNT 77 // number of samples to average
+
+ for (i = 0; i < COUNT; ++i) { // average multiple for more accuracy
+ uint16_t a, b, c;
- for (i = 0; i < 33; ++i) { // average multiple for more accuracy
- unsigned a, b, c;
-
- a = adc.read_u16(); // take median of 3 values
+ a = adc.read_u16(); // take median of 3 values to filter noise
b = adc.read_u16();
c = adc.read_u16();
if ((a >= b && a <= c) || (a >= c && a <= b)) sum += a;
else if ((b >= a && b <= c) || (b >= c && b <= a)) sum += b;
- else sum += c;
+ else sum += c;
+
} // for
- return sum / 33;
+ return sum / COUNT;
+
+} // read_temp()
+
+
+// read a temperature in A/D counts
+// adjust it for vref variations
+
+unsigned read_temp(int device)
+{
+unsigned value;
+unsigned max; // A/D reading for the vref supply voltage
-} // read_temp()
+ // send power to analog resistors only when needed
+ // this limits self heating
+
+ ad_power = 1; // turn on supply voltage
+ max = read_ad(vref); // read supply voltage
+
+ if (device == BOILER)
+ value = (read_ad(boiler) * 65536) / max; // scale to vref
+ else
+ value = (read_ad(group) * 65536) / max; // scale to vref
+
+ ad_power = 0;
+
+ return value;
+} // read_temp()
+
+