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Member since Aug 2016 • Last active Mar 2017
  • 2 conversations

Do something different.

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  • in Electronics
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    I was designing a microphone pre-amplifier circuit for Wireless Noise Monitoring application.

    I used an amplifier AD797AN (datasheet:http://www.kynix.com/uploadfiles/pdf/AD7­97AN.pdf ) which connected to a 9V power supply. The multisim simulation of the circuit with a function generator gives the expected gain of around 7.8. But the same circuit in the breadboard with the microphone gives the gain of only around 5. Please let me know what improvements are needed in the circuit to get the expected gain of 7.8?

  • in Electronics
    Avatar for user67013

    Hi! Why stm32F103ZET use serial port can't receive and send data?
    The system has been in smooth operation when configuration with USART1 program. The data's receiving and sending are very good. But it went wrong when I replaced usart1 instead of usart2.
    Serial port is not working properly. I don't know what's wrong. Please give me some suggestions.Thank you.

    u8 data;
    int main()

                USART_InitTypeDef USART_InitStruct;
                GPIO_InitTypeDef GPIO_InitStruct;
                 NVIC_InitTypeDef NVIC_InitStruct;
                RCC_APB2PeriphClockCmd(RCC_APB2Periph_GP­IOA, ENABLE);
                RCC_APB1PeriphClockCmd(RCC_APB1Periph_US­ART2, ENABLE);
                USART_InitStruct.USART_BaudRate = 115200;
                USART_InitStruct.USART_HardwareFlowContr­ol = USART_HardwareFlowControl_None;
                USART_InitStruct.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
                USART_InitStruct.USART_Parity = USART_Parity_No;
                USART_InitStruct.USART_StopBits = USART_StopBits_1;
                USART_InitStruct.USART_WordLength = USART_WordLength_8b;
          USART_Init(USART2, &USART_InitStruct);
                GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF_PP;
                GPIO_InitStruct.GPIO_Pin = GPIO_Pin_2;
                GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
                GPIO_Init(GPIOA, &GPIO_InitStruct);
                GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IN_FLOATING;
                GPIO_InitStruct.GPIO_Pin = GPIO_Pin_3;
                GPIO_Init(GPIOA, &GPIO_InitStruct);
                NVIC_InitStruct.NVIC_IRQChannel = USART2_IRQn;
                NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
                NVIC_InitStruct.NVIC_IRQChannelPreemptio­nPriority = 0;
                NVIC_InitStruct.NVIC_IRQChannelSubPriori­ty = 0;
                 USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);
                USART_Cmd(USART2, ENABLE);


    void USART2_IRQHandler(void)

                if(USART_GetFlagStatus(USART2, USART_IT_RXNE) != RESET)
                                USART_ClearFlag(USART2, USART_FLAG_RXNE);
                                data = USART_ReceiveData(USART2);
                                USART_SendData(USART2, data);
                                while(USART_GetFlagStatus(USART2, USART_FLAG_TXE) != SET);


    Best regards,