STM32F401VDT6 microcontroller :- PWM channel misbehaves after ESD (Electro Static Discharge) testing
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‎2022-04-21 3:48 AM
We have custom board, having STM32F401VDT6 microcontroller on it. We interfaced a tricolor LED to the Timer 1 PWM channels (CH1- Red, CH2-Green, CH3-Blue). Recently we have ESD test, after that when we stop channel 2 PWM and started CH3 PWM that time CH2's pin is continuously high. But when CH2 PWM is started then this pin behaves as expected (High-Low).
- What can be the reason for PWM channel to Pin High, even CH2 PWM is stopped?
- Is their any interlinks between the channels ?
- Does ESD affects the PWM peripheral of microcontroller?
- Labels:
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EMC
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STM32F4 Series
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TIM
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‎2022-04-21 5:50 AM
ESD affects everything it hits in a largely unpredictable ways...
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‎2022-04-21 6:10 AM
> CH2's pin is continuously high
- Are you sure this is incorrect behavior? Show the TIM registers.
- Everything is linked to some degree.
- Of course, potentially.
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‎2022-04-21 6:20 AM
> when we stop channel 2 PWM and started CH3 PWM that time CH2's pin is continuously high
What is "stop channel 2 PWM" in terms of TIM (and perhaps GPIO) registers? Why is this behaviour unexpected?
If "stop channel 2 PWM" means effectively threestating the pin, ESD testing might've opened some leak path to VDD, e.g. shorted the transistor which switches on the internal pullup. There's probably also a higher current consumption when the pin is driven (PWM is on), but the difference may be low, depending on circumstances.
JW
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‎2022-06-01 11:13 PM
In general, when PWM section is broken due to ESD damage, how is it broken? (Short circuit or open circuit or continuous high etc.)
