From e59d9f073bd2299134c234669faa48c386c45995 Mon Sep 17 00:00:00 2001 From: Till Date: Sat, 12 Sep 2020 02:27:49 +0200 Subject: [PATCH] Update thermistor_21.h reverted back to original code and added additional comment on intended usecase for this probe (5V INA826 supply, 3v3 ADC ref on mainboard) --- Marlin/src/module/thermistor/thermistor_21.h | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/Marlin/src/module/thermistor/thermistor_21.h b/Marlin/src/module/thermistor/thermistor_21.h index 65bc17b3a5..943cb484c5 100644 --- a/Marlin/src/module/thermistor/thermistor_21.h +++ b/Marlin/src/module/thermistor/thermistor_21.h @@ -23,10 +23,11 @@ #define REVERSE_TEMP_SENSOR_RANGE_21 1 -// Pt100 with INA826 amp with 3.3V excitation based on "Pt100 with INA826 amp on Ultimaker v2.0 electronics" -// As the uC ADC reference voltage is 3.3V as well as the INA826 supply/reference, the same table as for 5V excitation is valid. -// The ADC is referring his counts to the reference voltage as the IN826 opamp does scale the output voltage to the supply voltage in the analog domain. -// Note, that the quantization error of this table in conjunction with rounding of the temperature reading can result in a few degrees error most noticeable between datapoints, e.g. 25°C, 35°C, etc. +#undef OV_SCALE +#define OV_SCALE(N) (float((N) * 5) / 3.3f) + +// Pt100 with INA826 amplifier board with 5v supply based on "Pt100 with INA826 amp on Ultimaker v2.0 electronics" with 3v3 ADC reference on the mainboard +// If the ADC reference and INA826 board supply voltage are identical, use senosr no. 20 instead. const temp_entry_t temptable_21[] PROGMEM = { { OV( 0), 0 }, { OV(227), 1 }, @@ -73,3 +74,5 @@ const temp_entry_t temptable_21[] PROGMEM = { { OV(614), 500 } }; +#undef OV_SCALE +#define OV_SCALE(N) (N)