MPU9250.c
static uint8_t send_and_receive(uint8_t data) {
	while( (SSI1_SR_R & 0x00000001) == 0) {}		// wait until SSI transmit FIFO empty
	SSI1_DR_R = data;														// write into the data register, start data exchange
	while( (SSI1_SR_R & 0x00000004) == 0) {}		// wait until SSI receive FIFO not empty
	return SSI1_DR_R;														// ack received data
}
/* ----------------------- Internal API for reading/writing registers of MPU ----------------------------- */
// Send one byte via SPI and then wait for response

Internal API for reading/writing registers of MPU
Send one byte via SPI and then wait for response
Internal API for reading / writing registers of MPU Send one byte via SPI and then wait for response
static uint8_t send_and_receive(uint8_t data) {
	while( (SSI1_SR_R & 0x00000001) == 0) {}		
	SSI1_DR_R = data;														
	while( (SSI1_SR_R & 0x00000004) == 0) {}		
	return SSI1_DR_R;														
}
static uint8_t send_and_receive ( uint8_t data ) { while ( ( SSI1_SR_R & 0x00000001 ) == 0 ) { } SSI1_DR_R = data ; while ( ( SSI1_SR_R & 0x00000004 ) == 0 ) { } return SSI1_DR_R ; }
Internal API for reading/writing registers of MPU 
Send one byte via SPI and then wait for response
Internal API for reading / writing registers of MPU Send one byte via SPI and then wait for response
// wait until SSI transmit FIFO empty
 // write into the data register, start data exchange
 // wait until SSI receive FIFO not empty
 // ack received data
