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thermistor_troubleshooting [2016/04/16 16:24] – [Check Thermistor Wiring] Traumflug | thermistor_troubleshooting [2018/05/27 16:10] (current) – external edit (unknown user) | ||
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* //CT1// means to smooth out noise, it's not directly involved in the measurement circuitry. | * //CT1// means to smooth out noise, it's not directly involved in the measurement circuitry. | ||
* // | * // | ||
- | * //RT1// makes up a [[https:// | + | * //RT1// makes up a [[https:// |
- | Connecting components this way gives a voltage on the signal line which depends on the thermistor' | + | Connecting components this way gives a voltage on the signal line which depends on the thermistor' |
===== Hardware Measurements ===== | ===== Hardware Measurements ===== | ||
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Before searching for firmware misconfigurations, | Before searching for firmware misconfigurations, | ||
+ | ==== Thermistor Type ==== | ||
+ | |||
+ | Actually, thermistor type doesn' | ||
+ | |||
+ | During firmware configuration types matter a lot more, because there we want not only a working principle, but also reasonably accurate readings. | ||
==== Check Supply Voltage ==== | ==== Check Supply Voltage ==== | ||
- | Easiest way to do this is to disconnect the thermistor and measure voltage between both pins. With no thermistor connected, it should be full supply voltage, 3.3\_or 5\_volts depending on the controller. | + | Easiest way to do this is to disconnect the thermistor and measure voltage between both pins on the board. With no thermistor connected, it should be full supply voltage, 3.3\_or 5\_volts depending on the controller. |
==== Check Thermistor Wiring ==== | ==== Check Thermistor Wiring ==== | ||
- | This measurement is simple, too. Disconnect | + | This measurement is simple, too. Unplug |
Measuring the thermistor while it's plugged in gives false results. | Measuring the thermistor while it's plugged in gives false results. | ||
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==== Check Voltage on the Processor Pin ==== | ==== Check Voltage on the Processor Pin ==== | ||
- | This is what the firmware actually " | + | {{ : |
+ | |||
+ | This is what the firmware actually " | ||
+ | |||
+ | This measurement can be done without the processor installed. If one is installed, the firmware shouldn' | ||
+ | |||
+ | Without a thermistor connected, both pins should read full 3.3\_volts (5\_volts on 5\_V controllers). Connecting a thermistor at room temperature (not to these processor pins, but to the thermistor header on the board) should drop this not much, but a bit. Typically to 3.1\_... 3.2\_volts. | ||
+ | |||
+ | Warming the thermistor by hand might change that slightly, perhaps by another 0.05\_V drop. Warming the thermistor with a lighter or soldering iron (be careful to not overheat it!), should drop that voltage further, down to very low readings, like 0.5\_V. |
thermistor_troubleshooting.1460816677.txt.gz · Last modified: 2018/05/27 16:10 (external edit)