105 lines
1.9 KiB
C
105 lines
1.9 KiB
C
/*
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temp.c
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This file currently reads temp from a MAX6675 on the SPI bus.
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ALL VALUES are in units of 0.25 degrees celsius, so temp_set(500) will set the temperature to 125 celsius, and temp_get() = 600 is reporting a temperature of 150 celsius.
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the conversion to/from this unit is done in gcode.c, near:
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if (next_target.M == 104)
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next_target.S = decfloat_to_int(&read_digit, 4, 1);
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and
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// M105- get temperature
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case 105:
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uint16_t t = temp_get();
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*/
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#include "temp.h"
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#include "machine.h"
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#include "pinout.h"
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#include "clock.h"
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uint16_t current_temp = 0;
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uint16_t target_temp = 0;
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int16_t heater_p = 0;
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int16_t heater_i = 0;
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int16_t heater_d = 0;
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int32_t p_factor = 680;
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int32_t i_factor = 18;
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int32_t d_factor = 200;
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#define PID_SCALE 1024L
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uint16_t temp_read() {
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uint16_t temp;
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SPCR = MASK(MSTR) | MASK(SPE);
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WRITE(SS, 1);
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SPDR = 0;
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for (;(SPSR & MASK(SPIF)) == 0;);
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temp = SPDR << 8;
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SPDR = 0;
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for (;(SPSR & MASK(SPIF)) == 0;);
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temp |= SPDR;
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if ((temp & 0x8002) == 0) {
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// got "device id"
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if (temp & 4) {
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// thermocouple open
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}
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else {
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current_temp = temp >> 3;
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return current_temp;
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}
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}
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WRITE(SS, 0);
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return 0;
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}
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void temp_set(uint16_t t) {
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target_temp = t;
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}
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uint16_t temp_get() {
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return current_temp;
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}
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void temp_tick() {
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uint16_t last_temp = current_temp;
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temp_read();
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int16_t t_delta = target_temp - current_temp;
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// PID stuff
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heater_p = t_delta;
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heater_i += t_delta;
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// note: D follows temp rather than error so there's no large derivative when the target temperature changes
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heater_d = (current_temp - last_temp);
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uint8_t pid_output = (
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(
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(((int32_t) heater_p) * p_factor) +
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(((int32_t) heater_i) * i_factor) +
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(((int32_t) heater_d) * d_factor)
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) / PID_SCALE
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);
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#ifdef HEATER_PIN_PWMABLE
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HEATER_PIN_PWMABLE = pid_output
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#else
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if (pid_output >= 128) {
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enable_heater();
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}
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else {
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disable_heater();
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}
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#endif
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}
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