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LMX2820EVM: Programming the LMX2820 USING ST's CONTROLLER not TicsPro

User001
Prodigy 100 points
Part Number: LMX2820EVM
Other Parts Discussed in Thread: LMX2820, USB2ANY,

Q1. I am trying to write and read the register of LMX2820 EVM board using ST's Nucleo board, I use SPI connection it takes some effect but I am not able to read the register, Is there any other specific configuration or connection? I have used SCK=125KHz, and tried all SPI mode, 

Q2. what TP_SRREQP is for? do I have to configure that pin of EVM board, ? because I observe that even TICS Pro does not work properly without that. 

  • 0
    TI__Guru** 111720 points

    Hi Rajani,

    To read back, MSB = 1. The read back data will be coming out from MUXOUT pin right after the 8th SPI clock. 

    TP_SRREQP is a test point connecting to the USB2ANY as well as the SRREQP pin of the synthesizer. If you do not use SYSREF, you do not need to deal with this pin.

  • 0 in reply to Noel Fung
    Prodigy 100 points

    Do I have to write all the registers before I read ?

    I do as follow:

    1.programm the LMX2820EVM board using TICS pro and USB2ANY device with some Freq. which loads all the value and shows me the correct frequency as well on the Scope

    2.Disconnect USB2ANY 

    3.connect SPI Bus to Nucleo board and LMX2820EVM

    4.Reset the nucleo board which has following programme

    uint8_t Rb = 0x04; //Register Address 

    Rb = Rb | (1<<8); //set MSB


    HAL_GPIO_WritePin(GPIOF, GPIO_PIN_12, GPIO_PIN_SET);//CS Pin high

    HAL_GPIO_WritePin(GPIOF, GPIO_PIN_12, GPIO_PIN_RESET); //CS low
    HAL_SPI_Transmit(&hspi1, &Rb, 1, 1000);  //Transmit MSB + Address
    HAL_SPI_Receive(&hspi1, Rx_Data, 2, 1000); //Receive data
    HAL_GPIO_WritePin(GPIOF, GPIO_PIN_12, GPIO_PIN_SET); //CS high


    sprintf((char*)Buf,"Data is : 0x%X 0x%X \n",Rx_Data[0],Rx_Data[1]);
    HAL_UART_Transmit(&huart3,Buf, strlen((char *)Buf), 1000); 

    at the last in buffer I am getting 0x00 0x00

  • 0 in reply to User001
    TI__Guru** 111720 points

    HI Rajani,

    I do not familiar with the nucleo board. To debug, I suggest use a scope to capture the read and write SPI waveform from USB2ANY, compare it with the waveform generated from the nucleo board. 

  • 0 in reply to Noel Fung
    Prodigy 100 points

    Nucleo board is a kind of Evolution board of ST microcontroller,

    I will try to compare the waveforms and respond you,