Posted on September 03, 2013 at 21:50Hi everyone,
I have a problem with a stm32f207 device.
I use the NSS pin of the SPI2 as a GPO. (The chip select to my SPI2 devices comes from an external I2C IO expander).
NSS pin (I4) seems to be working ok as a GPO until I enable SPI2 interface.
If I have the I4 (NSS) high when I enable the SPI2 I can see that it goes to approx. 2v.
This means as far as I understand that the NSS pin goes low, which it should when I enable the SPI, but I have not assigned it to its alternative function.
Can anyone spot what I have missed?
I think this is the relevant init code�
//Configure PI.4 as motor control */
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
GPIO_Init(GPIOI, &GPIO_InitStructure);
// Connect PI.1 to SD_SPI pins: SCK
GPIO_PinAFConfig(GPIOI, GPIO_PinSource1, GPIO_AF_SPI2);
//Configure PI.2 as SD_SPI pins: MISO
GPIO_PinAFConfig(GPIOI, GPIO_PinSource2, GPIO_AF_SPI2);
//Configure PI.3 as SD_SPI pins: MOSI
GPIO_PinAFConfig(GPIOI, GPIO_PinSource3, GPIO_AF_SPI2);
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
// Configure CLK, MISO, MOSI pins
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3;
GPIO_Init(GPIOI, &GPIO_InitStructure);
// SPI configuration
SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
SPI_InitStructure.SPI_CPOL = SPI_CPOL_High;
SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;
SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_4;
SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
SPI_InitStructure.SPI_CRCPolynomial = 7;
SPI_Init(SPI2, &SPI_InitStructure);
/*!< Enable the SPI */
SPI_Cmd(SPI2, ENABLE);
#stm32f107-nss-gpio-spi2
