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USART2 VOLTAGE LEVELS

Question asked by kadam.kiran on Jun 12, 2015
hi everyone, I am using stm32f407 for my project and usart2 for communicating with gsm modem.past few days i am facing an issue that controller cannot communicate with modem.then i started checking my hardware step by step.doing so come to point where i noticed rx pin (modem removed )showing 1.8v logic level while tx shows 3.3v .i then configured usart rx as gpio and toggled led .it then shoed correct 3.3v level. why this is happening with usart mode only??due to this though modem responds i cannot capture response.usart and modem connected via level translator.1.8 to 3.3v. pls help me on this .

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