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pt100 [2017/03/09 02:55]
wolfmanjm
pt100 [2019/02/22 04:01] (current)
50.25.223.35 Cleaned up phrasing/grammar, added some missing articles.
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-A [[https://​en.wikipedia.org/​wiki/​Resistance_thermometer|PT100]] is a commonly used RTD. Compared to how Thermistor class works - it handles ​NTC'​s ​PT100 is PTC so the change in resistance with temperature is "other way around"​. PT100 also have very different curve than NTCs handled by Thermistor class.+A [[https://​en.wikipedia.org/​wiki/​Resistance_thermometer|PT100]] is a commonly used RTD. Compared to NTC (the most common) thermistors work, the PT100 is "PTC" ​so the change in resistance with temperature is "other way around"​. ​(PT100'​s ​also have very different curve than NTCs handled by Thermistor class.)
  
-PTC means positive temperature coefficient so electrical resistance increases with raising temperature. They cannot be used as-is, you must use an amplifier circuit so they become usable by SmoothieBoard.+"PTC" ​means "positive temperature coefficient" ​so electrical resistance increases with raising temperature. They cannot be used as-is, you must use an amplifier circuit ​to raise the voltage change ​so they become usable by SmoothieBoard.
  
-Currently Smoothie only supports E3D's PT100 amplifier board. Other PT100 amplifiers may be supported later (i.e. MAX38165 ​via SPI).+Currently Smoothie only supports E3D's PT100 amplifier board. Other PT100 amplifiers may be supported later (i.e. MAX31865 ​via SPI).
  
 <callout type="​danger"​ icon="​true">​ <callout type="​danger"​ icon="​true">​
-The PT100 E3D amplifier needs to be powered from the AVCC and AGND header pins on the SmoothieBoard,​ only newer boards have this header. DO NOT power from 5v or you will kill the port.+The PT100 E3D amplifier needs to be powered from the AVCC and AGND header pins on the SmoothieBoard,​ only newer boards have this header. 
 + 
 +If you do not have AVCC/AGND pins, you can use 3.3V and GND. However this may introduce noise in the ADC system and may affect all temperature readings from analog sources (i.e. thermistors and PT100). 
 + 
 +**DO NOT power from 5v or you will kill the port.**
 </​callout>​ </​callout>​
  
-You wire a PT100 //almost// the same way you would a thermistor, but you need to specify Smoothie it is a PT100 and where you connected the amplifier signal output:+You wire a PT100 //almost// the same way you would a thermistor, but you need to specify ​to Smoothie it is a PT100 and where you connected the amplifier signal output:
  
 <​code>​ <​code>​
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 temperature_control.hotend.e3d_amplifier_pin ​  ​1.30 ​       # must be a free ADC pin, not a temperature input temperature_control.hotend.e3d_amplifier_pin ​  ​1.30 ​       # must be a free ADC pin, not a temperature input
 </​code>​ </​code>​
 +
 +<callout type="​info"​ icon="​true">​
 +When using a PT100 sensor type you do not need to set values for the thermistor kind or thermistor_pin. If you do, these values will be ignored.
 +</​callout>​
  
 <callout type="​danger"​ icon="​true">​ <callout type="​danger"​ icon="​true">​