Interfacing LDC1000 EWM with Tiva Connected Launchpad

Hi All,

I got the LDC1000 EVM and was working away happily with the GUI and I love it so far. I hope to eventually use the sensor in a wind turbine orientation sensing capacity so I broke the EVM along the perforations (I hooked it all back together and was still working)

I then attempted to essentially replace the MSP430/USB side with my Tiva Connected Launchpad (EK-TM4C1294XL) and thus far I have had no success and I cannot figure out why.

Setup Summary:

LDC     TIVA

Vcc        5V  

Vio        3.3v  

And all of the spi signals are hooked up correctly. And I think the SPI port is configured correctly. (I.e. I've used SPI for other applications no problem).

I hooked the external clock up to a 8MHz signal generator.

Initially I just want to get this set up working without getting inductance or Rp readings .. i.e. read and write to the config regs.

The issue is that I do not get any data back form the LDC1000.

At this stage I am just trying to simply read the LDC's Device ID reg which the data sheet says should have a default value of 0x80 Hex.

So I set up the SPI port and place the following in the SPI port as follows:

/* Clock Gate enable for all of the gpio ports needed */
	   CLOCK_GATE_GPIO |=CLOCK_GATE_PORTS_D_E_H_M;

	   /* Clock Gate enable for the the SPI2 Module */
	   CLOCK_GATE_SPI  |= CLOCK_GATE_SSI2;

	   /* GPIO AFSEL For GPIOD 0,1,3*/
	   GPIO_PORTD_AHB_AFSEL_R |= (GPIO_PIN_0 | GPIO_PIN_1 | GPIO_PIN_3 );

	   /* Set up MUXs for SPI operation*/
	  GPIO_PORTD_AHB_PCTL_R |= ((0x0F<<0) | (0x0F<<4) | (0x0F<<12));

	   /* DEN for a SPI Pins */
	   GPIO_PORTD_AHB_DEN_R |=(SCLK | MISO | MOSI );

	   /* Configure the SPI Module for master operations */
	  SSI2_CR1_R =0;

	  /* Set the SPI Clock to USe the System Clock */
	  SSI2_CC_R  =0;

	  /* Set the Clock Pre-Scaler  */
	  SSI2_CPSR_R = 0x02; // Value taken from CCS

	  /* Set the Serial Clock Rate ... Set Up FreeScale SPI ... Set Up Data Size */
	  SSI2_CR0_R = 0x307;// Val taken from CCS //was 0x307

	  /* Enable the SSE bit to enable QSSI */
	  SSI2_CR1_R =(1u<<1);

I then initially perform a clear on the SPI Rx FiFO and attempt to read the LDC's Device ID Register as follows:

/* Enable LDC chip select */
CSn_DATA &= ~(CSn); // Can see this happening with scope

/* Put data in fifo. Set the R/W bit to 1 ..i.e. READ */
SPI_DATA_REG = (0x00 | 0x80); 

/* wait for the transmission to complete */
while(SPI_STATUS & SPI_BUSY);

/* Read the data returned from LDC1000 */
int val = SPI_DATA_REG;

/* Disable the chip select */
CSn_DATA |= (CSn);// Can see this happening with scope

 The issue is val is always zero no matter what register I try to read from

Am I correct in saying that the correct Tiva SPI port config is as follows:

Master Mode using the System Clock at 8 Bit with both SPO =0 and SPH = 0?

If someone can see something wrong here it would be great , I'm not expert at this stuff but I tend to eventually figure these things out but this has me stumped.

 Regards,

Jay Long

Additional Info:

the entities such as "SPI_STATUS"  and "CLOCK_GATE_SSI2" etc. above are tried and tested on numerous occasions and are essentially my easy to remember redefinitions of regs in m4c1294ncpdt.h

i.e.  #define SPI_STATUS SSI2_SR_R

The Setup uses the launchpads SSI2 port so PD0 = MISO  PD1= MOSI PD3= SCLK and I use a random gpio for CS as I prefer that over the Fss approach

SSI2_CR1_R etc is defined in TivaWare/inc/tm4c1294ncpdt.h

IDE = CCS v5