From 0e37fe87767c26675d3e320f2d0eb03ac9af1a3c Mon Sep 17 00:00:00 2001
From: AnHardt <github@kitelab.de>
Date: Sun, 10 Feb 2019 10:54:45 +0100
Subject: [PATCH] Apply minimum C in M303 (#13113)
Apply minimum `C` in `M303`. `PID_autotune()` needs to be called with a 'C'ycles-parameter >2 to give meaningful (different from 0) PID-factors. Therefore silently raise C to 3. Fixing one aspect of #13104
---
Marlin/src/gcode/temperature/M303.cpp | 2 +-
Marlin/src/module/temperature.cpp | 4 +++-
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/Marlin/src/gcode/temperature/M303.cpp b/Marlin/src/gcode/temperature/M303.cpp
index f701277854..874264bcbd 100644
--- a/Marlin/src/gcode/temperature/M303.cpp
+++ b/Marlin/src/gcode/temperature/M303.cpp
@@ -32,7 +32,7 @@
*
* S<temperature> sets the target temperature. (default 150C / 70C)
* E<extruder> (-1 for the bed) (default 0)
- * C<cycles>
+ * C<cycles> Minimum 3. Default 5.
* U<bool> with a non-zero value will apply the result to current settings
*/
void GcodeSuite::M303() {
diff --git a/Marlin/src/module/temperature.cpp b/Marlin/src/module/temperature.cpp
index cf6e16c24a..b909caf158 100644
--- a/Marlin/src/module/temperature.cpp
+++ b/Marlin/src/module/temperature.cpp
@@ -330,6 +330,8 @@ uint8_t Temperature::soft_pwm_amount[HOTENDS];
*
* Alternately heat and cool the nozzle, observing its behavior to
* determine the best PID values to achieve a stable temperature.
+ * Needs sufficient heater power to make some overshoot at target
+ * temperature to succeed.
*/
void Temperature::PID_autotune(const float &target, const int8_t heater, const int8_t ncycles, const bool set_result/*=false*/) {
float current = 0.0;
@@ -540,7 +542,7 @@ uint8_t Temperature::soft_pwm_amount[HOTENDS];
break;
}
- if (cycles > ncycles) {
+ if (cycles > ncycles && cycles > 2) {
SERIAL_ECHOLNPGM(MSG_PID_AUTOTUNE_FINISHED);
#if HAS_PID_FOR_BOTH
--
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