First Layer Calibration using other filament  

First Layer Calibration using other filament

I updated the firmware on my MK3 to 3.2.0, and needed to re-do the First Layer adjustment. Although I normally use PET filament, the LCD menu insisted that I had to use PLA. I even got on a Chat with Prusa about this, and tried preheating the hot end to PET temperature - but when the First Layer adjustment started, the setpoint reverted back to PLA temperature. It was possible to override the setting after the process started, but it was definitely not convenient.

So here's a mod that I inserted in "ultralcd.cpp" What this mod does is check to see if the hot end is already preheated (i.e. setTargteHotend is true). If it is, then the setpoint temperature won't be changed; it will stay wherever you had it. I didn't change the message in the Language file, so it still asks me if I have loaded PLA - but I can just say "Yes" if I've preheated the hot end for the plastic I'm using. (Note that there are two blocks of code very similar, one where "SNMM" is defined and one where it's not; the one I used here is where it's not - meaning an EINSY board instead of a RAMBO board)
EDIT: Oops! Apparently setTargetHotend is not the right flag to use. If you do this mod as I did, you MUST preheat your hot end and bed; it's not optional. Maybe someone knows the right variable to key on that really does tell when the hot end is at a setpoint temperature?

if (lcd_commands_type == LCD_COMMAND_V2_CAL) //Live Adjust Z
{
char cmd1[30];
float width = 0.4;
float length = 20 - width;
float extr = count_e(0.2, width, length);
float extr_short_segment = count_e(0.2, width, width);
if(lcd_commands_step>1) lcd_timeoutToStatus = millis() + LCD_TIMEOUT_TO_STATUS; //if user dont confirm live adjust Z value by pressing the knob, we are saving last value by timeout to status screen
if (lcd_commands_step == 0)
{
lcd_commands_step = 9;
}
if (lcd_commands_step == 9 && !blocks_queued() && cmd_buffer_empty())
{
//HERE IS THE MOD...
if (!setTargetHotend) {
enquecommand_P(PSTR("M107"));
enquecommand_P(PSTR("M104 S" STRINGIFY(PLA_PREHEAT_HOTEND_TEMP)));
enquecommand_P(PSTR("M140 S" STRINGIFY(PLA_PREHEAT_HPB_TEMP)));
enquecommand_P(PSTR("M190 S" STRINGIFY(PLA_PREHEAT_HPB_TEMP)));
enquecommand_P(PSTR("M109 S" STRINGIFY(PLA_PREHEAT_HOTEND_TEMP)));
}
//END OF MOD...
enquecommand_P(MSG_M117_V2_CALIBRATION);
enquecommand_P(PSTR("G87")); //sets calibration status
enquecommand_P(PSTR("G28"));
enquecommand_P(PSTR("G92 E0.0"));
lcd_commands_step = 8;
}
...