SSP1_MISO versus MII_TXD1

spigeon · ‎2008-02-13

Posted on February 13, 2008 at 12:02

spigeon · ‎2011-05-17

Posted on May 17, 2011 at 09:49

Me again... here's the code

// Enable peripheral clock for SSP1 and its GPIO port (GPIO3)

SCU_APBPeriphClockConfig(__SSP1 ,ENABLE);

SCU_APBPeriphClockConfig(__GPIO3 ,ENABLE);

SCU_APBPeriphClockConfig(__GPIO1 ,ENABLE);

GPIO_DeInit(GPIO3);

GPIO_DeInit(GPIO1);

// Gonfigure SSP1_CLK, SSP1_MOSI

GPIO_InitStructure.GPIO_Direction = GPIO_PinOutput;

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4| GPIO_Pin_6;

GPIO_InitStructure.GPIO_Type = GPIO_Type_PushPull ;

GPIO_InitStructure.GPIO_IPConnected = GPIO_IPConnected_Enable;

GPIO_InitStructure.GPIO_Alternate = GPIO_OutputAlt2 ;

GPIO_Init (GPIO3, &GPIO_InitStructure);

// IMPORTANT! NSS IPConnected must be disabled, or SPI enters loopback mode!

GPIO_InitStructure.GPIO_Direction = GPIO_PinOutput;

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;

GPIO_InitStructure.GPIO_Type = GPIO_Type_PushPull;

GPIO_InitStructure.GPIO_IPConnected = GPIO_IPConnected_Disable;

GPIO_InitStructure.GPIO_Alternate = GPIO_OutputAlt2;

GPIO_Init (GPIO3, &GPIO_InitStructure);

// Gonfigure SSP1_MISO pin

GPIO_InitStructure.GPIO_Direction = GPIO_PinInput;

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;

GPIO_InitStructure.GPIO_Type = GPIO_Type_PushPull ;

GPIO_InitStructure.GPIO_IPConnected = GPIO_IPConnected_Enable;

GPIO_InitStructure.GPIO_Alternate = GPIO_InputAlt1 ;

GPIO_Init (GPIO3, &GPIO_InitStructure);

// Configure SSP1 for SPI Master, Mode 3, 8-bits, 12.5 MHz

SSP_DeInit(SSP1);

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_8b;

SSP_InitStructure.SSP_ClockPrescaler = 2;

SSP_InitStructure.SSP_ClockRate = 0;

SSP_Init(SSP1, &SSP_InitStructure);

SSP_Cmd(SSP1, ENABLE);

SSP_LoopBackMode(SSP1, DISABLE);

// Enable GPIO0.1 (Chip Select for AT45DB161D)

SCU_APBPeriphClockConfig(__GPIO0, ENABLE);

GPIO_DeInit(GPIO0);

GPIO_InitStructure.GPIO_Direction = GPIO_PinOutput;

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;

GPIO_InitStructure.GPIO_Type = GPIO_Type_PushPull;

GPIO_InitStructure.GPIO_IPConnected = GPIO_IPConnected_Disable;

GPIO_InitStructure.GPIO_Alternate = GPIO_OutputAlt1;

GPIO_Init (GPIO0, &GPIO_InitStructure);

// Configure MII_TXD1

SCU_APBPeriphClockConfig(__GPIO1, ENABLE);

GPIO_DeInit(GPIO1);

GPIO_InitStructure.GPIO_Direction = GPIO_PinOutput;

GPIO_InitStructure.GPIO_Type = GPIO_Type_PushPull;

GPIO_InitStructure.GPIO_IPConnected = GPIO_IPConnected_Enable;

GPIO_InitStructure.GPIO_Alternate = GPIO_OutputAlt2;

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;

// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

// Culprit right here! With this next line of code commented out,

// the loop below reads the status register frrom the AT45DB161D properly.

// Otherwise, it reads 0's.

// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

GPIO_Init(GPIO1, &GPIO_InitStructure);

while ( 1 ) {

// Chip select

GPIO_WriteBit ( GPIO0, GPIO_Pin_1, Bit_RESET );

// Read status register

SSP_SendData ( SSP1, 0xD7 );

SSP_SendData ( SSP1, 0x00 );

while ( SSP_GetFlagStatus ( SSP1, SSP_FLAG_RxFifoNotEmpty ) == RESET );

x = SSP_ReceiveData(SSP1);

while ( SSP_GetFlagStatus ( SSP1, SSP_FLAG_RxFifoNotEmpty ) == RESET );

x = SSP_ReceiveData(SSP1);

// Chip deselect

GPIO_WriteBit ( GPIO0, GPIO_Pin_1, Bit_SET );

}

[ This message was edited by: spigeon on 13-02-2008 15:34 ]

spigeon · ‎2011-05-17

Posted on May 17, 2011 at 09:49

Okay, I am at my wit's end with this problem...

STR912FAW44

I am using SSP1 in master mode, Motorola format, to communicate with a serial flash device from Atmel. SSP1_MISO is connected to P3.5.

Everything works fine.

Then, I initialize the MAC controller, and bang! Can't read anything other than 0's on SSP1_MISO !

As soon as I configure the MAC contoller's P1.2 as an output pin (MII_TXD1), it seems like SSP1_MISO becomes disabled. Using a scope, I see a perfectly normal SPI transaction, and the correct data from the serial flash arrives at P3.5. But the FIFO contains 0's !

Funny observation: P1.2 (MII_TXD1) also happens to be an alternate input function for SSP1_MISO. It's almost like configuring P1.2 as an output pin causes not only P1.2 to be unusable for SSP1_MISO, but P3.5 as well...

Anyone has an idea ??? I could post my code, but I'm not at work at this moment...

[ This message was edited by: spigeon on 12-02-2008 14:25 ]

spigeon · ‎2011-05-17

Posted on May 17, 2011 at 09:49

Found the problem and I am rather angry that I had to spend a whole day looking for the answer.

When configuring P1.2 (MII_TXD2), it should be:

GPIO_InitStructure.GPIO_IPConnected = GPIO_IPConnected_Disable;

instead of :

GPIO_InitStructure.GPIO_IPConnected = GPIO_IPConnected_Enable;

IPConnected_Enable only applies to input pins - this raises the AltInput1 bit in the SCU_GPIOIN register. Therefore, I had SSP1_MISO enabled on P1.2 and on P3.5, which is illegal.

But the damned line with IPConnected_Enable was taken from source code that came with my IAR compiler (web server example on the STR912-SK, using uIP), here:

C:\Program Files\IAR Systems\Embedded Workbench 4.0\ARM\examples\ST\STR91x\STR912-SK-IAR\uip_webserver\modules\str912_enet.c