1. Hardware settings

DSPI eDMA Demo program needs the following hardware:

TWR-K64F120M, FRDMK64F120M

2. Download program

Download the program to the target board.
Connect a USB cable to the PC host and open a serial terminal at 115200 baud, 8-bits no parity, 1 stop bit.
When successfully connected, the program sends "Press spacebar to begin." to the terminal. Then you should press space key to continue. Communication Interface Settings:
- TWR-K64F120M(OpenSDA) UART1, TX: PTC3 RX: PTC4.
- FRDM-K64F120M(OpenSDA) UART0, TX: PTB16 RX: PTB17.

3. Run the program

The following will appear in the terminal window:

DSPI eDMA Demo

DSPI Transfers using eDMA

Configuration:

Setting	Value
Terminal Baud:	115200 bps
TDSPI Bit rate:	5000 bps
TDSPI Master:	DSPI0
TDSPI Slave:	DSPI1

Connection on TWR-K64F120M:

Master	Slave
SS PTD0	PTB10
SCK PTD1	PTB11
MstOut PTD2	PTB17 SlvIn
MstIn PTD3	PTB16 SlvOut

Connection on FRDM-K64F120M:

Master	Slave
SS PTD0	PTD4
SCK PTD1	PTD5
MstOut PTD2	PTD7 SlvIn
MstIn PTD3	PTD6 SlvOut

This indicates the speed of the SPI transfers, and what pins to connect and how to connect them.

Key Functions

1.

void dspi_edma_master_setup(uint8_t instance, uint32_t baudRateHz, uint8_t transferSizeBits)

Takes in the DSPI module instance, the desired data rate of DSPI transfers, and the frame size of the data transfer. Initializes master instance of DSPI.

Parameters

instance	DSPI module instance
baudRateHz	Pass in the desired baud rate of DSPI transfers in Hz.
transferSizeBits	Pass data frame size (8 or 16 bit)

2.

void dspi_edma_slave_setup(uint8_t instance, uint8_t transferSizeBits)

Takes in the DSPI module instance, and the frame size of the data transfer. Initializes slave instance of DSPI.

Parameters

instance	DSPI module instance
transferSizeBits	Pass data frame size (8 or 16 bit)

3.

dspi_status_t data_source(uint8_t * sourceWord, uint32_t instance)

Callback function for DSPI slave. Used to transmit data from slave. In this application it generates slave data out, the data out is a count.

Parameters

sourceWord	8-bit data variable to be passed to slave PUSHR register.
instance	Instance of the DSPI module.

4.

void on_error(dspi_status_t error, uint32_t instance)

Callback function for DSPI slave. Used to handle errors. In this application is sets the error flag to signal the end of the demonstration.

Parameters

error	Uses dspi_status_t value given by driver interrupt handler.
instance	Instance of the DSPI module.

5.

void setup_edma_loop(edma_loop_setup_t *loopSetup, uart_state_t *uart)

Configures an eDMA transfer loop using a loopSetup structure, and if a valid uart_state_t is passed will print out the TCD for that loop.

Parameters

loopSetup	Data structure defined by user, containing all the parameters for the eDMA loop.
uart	Pointer to a valid uart_state_t for debug printing.

6.

void disable_edma_loop(edma_loop_setup_t *loopSetup, uart_state_t *uart)

Disables user configured eDMA transfer loop. Also, will free memory allocated by eDMA transfer loop. If a valid uart_state_t is passed will print out the TCD for that loop.

Parameters

loopSetup	Data structure defined by user, containing all the parameters for the eDMA loop.
uart	Pointer to a valid uart_state_t for debug printing.

7.

void *mem_align(size_t ptrSize, uint32_t alignment)

Function to peform aligned data memory allocation. Useful when memalign is not available.

Parameters

ptrSize	size_t variable to pass size of memory to be allocated
alignment	uint32_t variable to pass byte size to align data with

Returns: pointer to aligned & allocated memory

8.

void free_align(void *ptr)

Function to free memory allocated by mem_align

Parameters

ptr	pointer that has been allocated with mem_align