From fcc29fc189d6289d01f3983867a17b63191035b2 Mon Sep 17 00:00:00 2001 From: Till Date: Thu, 19 Nov 2020 21:07:47 +0100 Subject: [PATCH] Add Thermistor 20-21 notes (#19246) --- Marlin/Configuration.h | 6 ++++-- Marlin/src/module/thermistor/thermistor_21.h | 3 ++- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/Marlin/Configuration.h b/Marlin/Configuration.h index 4521895fdc..9d2dd0b710 100644 --- a/Marlin/Configuration.h +++ b/Marlin/Configuration.h @@ -375,8 +375,10 @@ * 13 : 100k Hisens 3950 1% up to 300°C for hotend "Simple ONE " & "Hotend "All In ONE" * 15 : 100k thermistor calibration for JGAurora A5 hotend * 18 : ATC Semitec 204GT-2 (4.7k pullup) Dagoma.Fr - MKS_Base_DKU001327 - * 20 : Pt100 with circuit in the Ultimainboard V2.x with 5v excitation (AVR) - * 21 : Pt100 with circuit in the Ultimainboard V2.x with 3.3v excitation (STM32 \ LPC176x....) + * 20 : Pt100 with circuit in the Ultimainboard V2.x with mainboard ADC reference voltage = INA826 amplifier-board supply voltage. + * NOTES: (1) Must use an ADC input with no pullup. (2) Some INA826 amplifiers are unreliable at 3.3V so consider using sensor 147, 110, or 21. + * 21 : Pt100 with circuit in the Ultimainboard V2.x with 3.3v ADC reference voltage (STM32, LPC176x....) and 5V INA826 amplifier board supply. + * NOTE: ADC pins are not 5V tolerant. Not recommended because it's possible to damage the CPU by going over 500°C. * 22 : 100k (hotend) with 4.7k pullup to 3.3V and 220R to analog input (as in GTM32 Pro vB) * 23 : 100k (bed) with 4.7k pullup to 3.3v and 220R to analog input (as in GTM32 Pro vB) * 30 : Kis3d Silicone heating mat 200W/300W with 6mm precision cast plate (EN AW 5083) NTC100K / B3950 (4.7k pullup) diff --git a/Marlin/src/module/thermistor/thermistor_21.h b/Marlin/src/module/thermistor/thermistor_21.h index cd867df291..2ca705b950 100644 --- a/Marlin/src/module/thermistor/thermistor_21.h +++ b/Marlin/src/module/thermistor/thermistor_21.h @@ -26,7 +26,8 @@ #undef OV_SCALE #define OV_SCALE(N) (float((N) * 5) / 3.3f) -// Pt100 with INA826 amp with 3.3v excitation based on "Pt100 with INA826 amp on Ultimaker v2.0 electronics" +// Pt100 with INA826 amplifier board with 5v supply based on Thermistor 20, with 3v3 ADC reference on the mainboard. +// If the ADC reference and INA826 board supply voltage are identical, Thermistor 20 instead. const temp_entry_t temptable_21[] PROGMEM = { { OV( 0), 0 }, { OV(227), 1 },