STR912 SSP -> NSS-Pin Connection

[hwunsch9]

Posted on June 15, 2012 at 12:40

Problem: Can't read out the received SSP0 Signal.

[ADC_VALUE = SSP_ReceiveData(SSP0)] Is it necessary to connect the NSS-Pin to high ? The uC is in Master Mode, MOSI, MISO and CLK Pins are connected. The NSS Pin is used and configured actually as output to start the /CONV Signal at the external SSP - ADC. Also the measured signals on MOSI, MISO and CLK are o.k. In Loop-Mode the received Signal is the SendData 0x800. So Loop-Mode is also o.k. Read SSP-Sequenz in main:  SSP_SendData(SSP0, 0x800);  // Read Signal channel0 -> 0x800  while(SSP_GetFlagStatus(SSP0, SSP_FLAG_RxFifoNotEmpty)==RESET);  ADC_VALUE = SSP_ReceiveData(SSP0); Setup:

GPIO_InitTypeDef GPIO_InitStructure;

SSP_InitTypeDef SSP_InitStructure; SCU_APBPeriphClockConfig(__GPIO2 ,ENABLE); SCU_APBPeriphClockConfig(__SSP0, ENABLE);    // GPIO2 Configuration    // SPP0 clk bus, GPIO2.4    GPIO_DeInit(GPIO2);    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;    GPIO_InitStructure.GPIO_Direction = GPIO_PinOutput;    GPIO_InitStructure.GPIO_Type = GPIO_Type_PushPull;    GPIO_InitStructure.GPIO_Alternate = GPIO_OutputAlt2;    GPIO_Init (GPIO2,&GPIO_InitStructure);

   // SSP0 MOSI bus, GPIO2.5 

   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;    GPIO_InitStructure.GPIO_Direction = GPIO_PinOutput;    GPIO_InitStructure.GPIO_Type = GPIO_Type_PushPull;    GPIO_InitStructure.GPIO_Alternate = GPIO_OutputAlt2;    GPIO_Init (GPIO2,&GPIO_InitStructure);       // SSP0 MISO bus, GPIO2.6    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 ;    GPIO_InitStructure.GPIO_Direction = GPIO_PinInput;    GPIO_InitStructure.GPIO_Type = GPIO_Type_PushPull;    GPIO_InitStructure.GPIO_IPInputConnected = GPIO_IPInputConnected_Enable;    GPIO_InitStructure.GPIO_Alternate = GPIO_InputAlt1;    GPIO_Init (GPIO2, &GPIO_InitStructure);

   // SSP0 CONV, GPIO2.7 -> LTC1861, ADC

   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7 ;    GPIO_InitStructure.GPIO_Direction = GPIO_PinOutput;    GPIO_InitStructure.GPIO_Type = GPIO_Type_PushPull;    GPIO_InitStructure.GPIO_Alternate = GPIO_OutputAlt1;    GPIO_Init (GPIO2, &GPIO_InitStructure);

  SCU_APBPeriphReset(__SSP0,ENABLE);

  SCU_APBPeriphReset(__SSP0,DISABLE);

  SSP_StructInit(&SSP_InitStructure);

  SSP_DeInit(SSP0);

  SSP_Cmd(SSP0, ENABLE);

  SSP_InitStructure.SSP_FrameFormat = SSP_FrameFormat_Motorola;

  SSP_InitStructure.SSP_Mode = SSP_Mode_Master;   SSP_InitStructure.SSP_CPOL = SSP_CPOL_High;   SSP_InitStructure.SSP_CPHA = SSP_CPHA_2Edge;   SSP_InitStructure.SSP_DataSize = SSP_DataSize_12b;   SSP_InitStructure.SSP_ClockRate = 20;     SSP_InitStructure.SSP_ClockPrescaler = 10;   SSP_Init(SSP0, &SSP_InitStructure);

  SSP_LoopBackConfig(SSP0, DISABLE);

Heiko