Hi,
I want to use the CC2538 SPI-0 port as slave interface. To try the SPI slave mode out, I have modified the provided SPI master example in the following way:
int
main(void)
{
uint32_t pui32DataTx[NUM_SSI_DATA];
uint32_t pui32DataRx[NUM_SSI_DATA];
uint32_t ui32Index;
//
// Set the clocking to run directly from the external crystal/oscillator.
// (no ext 32k osc, no internal osc)
//
SysCtrlClockSet(false, false, SYS_CTRL_SYSDIV_32MHZ);
//
// Set IO clock to the same as system clock
//
SysCtrlIOClockSet(SYS_CTRL_SYSDIV_32MHZ);
//
// Set up the serial console to use for displaying messages. This is
// just for this example program and is not needed for SSI operation.
//
InitConsole();
//
// Display the setup on the console.
//
UARTprintf("SSI ->\n");
UARTprintf(" Mode: SPI\n");
UARTprintf(" Data: 8-bit\n\n");
//
// The SSI0 peripheral must be enabled for use.
//
SysCtrlPeripheralEnable(SYS_CTRL_PERIPH_SSI0);
//
// Disable SSI function before configuring module
//
SSIDisable(SSI0_BASE);
//
// Set IO clock as SSI clock source
//
SSIClockSourceSet(SSI0_BASE, SSI_CLOCK_PIOSC);
//
// For this example SSI0 is used with PA2-PA5. The actual port and pins
// used may be different on your part, consult the data sheet for more
// information. GPIO port A needs to be enabled so these pins can be used.
// TODO: change this to whichever GPIO port you are using.
//
// Configure the pin muxing for SSI0 functions on port A2, A3, A4, and A5.
// This step is not necessary if your part does not support pin muxing.
// TODO: change this to select the port/pin you are using.
//
IOCPinConfigPeriphInput(EXAMPLE_GPIO_SSI_BASE, EXAMPLE_PIN_SSI_CLK,
IOC_CLK_SSI_SSI0);
IOCPinConfigPeriphInput(EXAMPLE_GPIO_SSI_BASE, EXAMPLE_PIN_SSI_FSS,
IOC_SSIFSSIN_SSI0);
IOCPinConfigPeriphOutput(EXAMPLE_GPIO_SSI_BASE, EXAMPLE_PIN_SSI_TX,
IOC_MUX_OUT_SEL_SSI0_TXD);
IOCPinConfigPeriphInput(EXAMPLE_GPIO_SSI_BASE, EXAMPLE_PIN_SSI_RX,
IOC_SSIRXD_SSI0);
//
// Configure the GPIO settings for the SSI pins. This function also gives
// control of these pins to the SSI hardware. Consult the data sheet to
// see which functions are allocated per pin.
// The pins are assigned as follows:
// PA5 - SSI0Tx
// PA4 - SSI0Rx
// PA3 - SSI0Fss
// PA2 - SSI0CLK
// TODO: change this to select the port/pin you are using.
//
GPIOPinTypeSSI(EXAMPLE_GPIO_SSI_BASE, EXAMPLE_PIN_SSI_CLK |
EXAMPLE_PIN_SSI_FSS | EXAMPLE_PIN_SSI_RX |
EXAMPLE_PIN_SSI_TX);
GPIOPinTypeSSI(EXAMPLE_GPIO_SSI_BASE, EXAMPLE_PIN_SSI_CLK |
EXAMPLE_PIN_SSI_RX | EXAMPLE_PIN_SSI_TX);
//
// Configure SSI module to Motorola/Freescale SPI mode 3:
// Polarity = 1, SCK steady state is high
// Phase = 1, Data changed on first and captured on second clock edge
// Word size = 8 bits
//
SSIConfigSetExpClk(SSI0_BASE, SysCtrlIOClockGet(), SSI_FRF_MOTO_MODE_3,
SSI_MODE_SLAVE, SysCtrlClockGet()/64, 8);
//
// Enable the SSI0 module.
//
SSIEnable(SSI0_BASE);
//
// Read any residual data from the SSI port. This makes sure the receive
// FIFOs are empty, so we don't read any unwanted junk. This is done here
// because the SPI SSI mode is full-duplex, which allows you to send and
// receive at the same time. The SSIDataGetNonBlocking function returns
// "true" when data was returned, and "false" when no data was returned.
// The "non-blocking" function checks if there is any data in the receive
// FIFO and does not "hang" if there isn't.
//
while(SSIDataGetNonBlocking(SSI0_BASE, &pui32DataRx[0]))
{
}
//
// Receive indefinite.
//
while(1)
{
//
// Receive the data using the "blocking" Get function. This function
// will wait until there is data in the receive FIFO before returning.
//
SSIDataGet(SSI0_BASE, &pui32DataRx[0]);
//
// Since we are using 8-bit data, mask off the MSB.
//
pui32DataRx[0] &= 0x00FF;
//
// Display the data that SSI0 received.
//
UARTprintf("'%c' ", pui32DataRx[0]);
}
...
I am not able to receive data as SPI slave. In master mode I can transmit and receive data.
I am aware that I have to use the correct pins (CLK is input, FSS is input MISO is output and MOSI is input). I have the connections made accordingly.
My impression is, that the pin multiplexing is incorrect. I do not get the master provided clock signal, there are no interrupts occurring.
Thank you for your help!
Frank
