TWI AND SPI in a single code

Question

Hi , 
 Need a bit of help here. 
 I am trying to use TWI and SPI in a single code for communicating with two different slave devices, the LTC2941 coulomb counter and the EM4325 RFID tag. I have written a switch case program similar to the one given in SDK 12.3.0 , and added an SPI case for the same. Here is a snippet of my main function (it is similar to the twis_master_with_twis_slave code provided in the SDK) : 
 
 int main(void)
{
 ret_code_t err_code;
 /* Initialization of UART */
 bsp_board_leds_init();

 APP_ERROR_CHECK(NRF_LOG_INIT(NULL));

 /* Initializing simulated EEPROM */
 err_code = eeprom_simulator_init();
 APP_ERROR_CHECK(err_code);

 /* Initializing TWI master interface for EEPROM */
 err_code = twi_master_init();
 APP_ERROR_CHECK(err_code);
 
 
 
 while (1)
 
 { 

 nrf_delay_us(9000) ; 
 
 // Welcome message 
 NRF_LOG_RAW_INFO(
 "
 
 This battery state of charge example 
"
 "You can access coulumb counter and rfid using following commands:
"
 );
 help_print();

 NRF_LOG_FLUSH();
 uint8_t c = NRF_LOG_GETCHAR();

 switch ((char)c)
 {
 case '
':
 case '':
 break;
 case 'p': // print eeprom data 
 do_print_data();
 break;
 
 case 'w': // configure or write into ltc2941 
 //do_string_write();
 write_into_kunal_ltc2941(); 
 break;
 
 case 'c': // clear the eeprom data 
 do_clear_eeprom();
 break;
 
 case 'q': // get the state of charge 
 SOC(); 
 break ; 
 
 
 case 's': // swap the battery and store data in the rfid tag 
 rfid_spi() ;
 break ; 
 
 case 'x':
 {
 uint32_t error = eeprom_simulator_error_get_and_clear();
 NRF_LOG_WARNING("Error word: %x
", (unsigned int)error);
 } 
 break;

 
 
 default:
 NRF_LOG_RAW_INFO("You selected %c
", (char)c);
 NRF_LOG_RAW_INFO("Unknown command, try one of the following:
");
 help_print();
 break;
 }
 if (eeprom_simulator_error_check())
 {
 NRF_LOG_RAW_INFO(
 "WARNING: EEPROM transmission error detected.
"
 "Use 'x' command to read error word.
"
 );
 }
 NRF_LOG_FLUSH();
 }
 
}

EM4325 datasheet : http://www.emmicroelectronic.com/products/rf-identification-security/epc-and-uhf-ics/em4325 
 LTC 2941 datasheet : http://cds.linear.com/docs/en/datasheet/2941fb.pdf 
 Here is the rfid_spi() function which is being called inside the switch case statement for communicating with EM4325 : 
 
 static void rfid_spi(void)
{
	uint32_t spike_clk = 24 ;
	uint32_t spike_miso = 23;
	uint32_t spike_mosi = 22 ;
	

	nrf_spim_enable( (NRF_SPIM_Type *)SPI_INSTANCE); 
	
	//nrf_spim_event_clear((NRF_SPIM_Type *)SPI_INSTANCE , NRF_SPI_EVENT_READY ) ;
	
	nrf_spim_configure((NRF_SPIM_Type *) SPI_INSTANCE , NRF_SPIM_MODE_0 , NRF_SPIM_BIT_ORDER_MSB_FIRST) ; 
	
	nrf_spim_pins_set( (NRF_SPIM_Type *)SPI_INSTANCE , spike_clk ,spike_mosi, spike_miso ) ;
	
	nrf_spim_frequency_set((NRF_SPIM_Type *)SPI_INSTANCE, NRF_SPIM_FREQ_250K);
	
//	nrf_spim_int_enable ((NRF_SPIM_Type *)SPI_INSTANCE,SPI_INTENSET_READY_Set) ;

 //memset(m_rx_buf, 0, 20); //m_length
 spi_xfer_done = false;
 const uint8_t p1 = 0xff; 
 const uint8_t p2 = 0x65;
 m_tx_buf[0] = 0xE8; /**< TX buffer. */
 m_tx_buf[1] = 0x2c;
 m_tx_buf[2] = 0xee ;
 m_tx_buf[3] = 0xab;
	
	nrf_gpio_cfg_output(25) ; // slave select pin 
	nrf_gpio_pin_clear(25) ; // set ss pin to low to activate SPI 
	
	nrf_spim_task_trigger((NRF_SPIM_Type *)SPI_INSTANCE, NRF_SPIM_TASK_START ) ;	// start spi
	
	bool gg =	nrf_spim_event_check ( (NRF_SPIM_Type *) SPI_INSTANCE, NRF_SPIM_EVENT_STARTED ) ;
	NRF_LOG_RAW_INFO("
 has spi started? %x 
",gg) ;
	
	for (int i=0 ; i<sizeof(m_tx_buf) ; i++){
	
	nrf_spim_tx_buffer_set((NRF_SPIM_Type *)SPI_INSTANCE , &(m_tx_buf[i]), 5 ) ;
	bool gg = nrf_spim_event_check((NRF_SPIM_Type *) SPI_INSTANCE, NRF_SPIM_EVENT_STARTED ) ;
	NRF_LOG_RAW_INFO("event is %x % 
", gg);
	}

	nrf_delay_us(8000) ; //delay required for EM4325 write operation.
	
	for (int i=0 ; i<sizeof(m_rx_buf) ; i++){
	nrf_spim_rx_buffer_set((NRF_SPIM_Type *)SPI_INSTANCE,&m_rx_buf[i],20) ;
	NRF_LOG_RAW_INFO("
 receive buffer byte %d = %x % 
", i, m_rx_buf[i]);

	}
	nrf_gpio_pin_set(25) ;
	nrf_spim_disable( (NRF_SPIM_Type *) SPI_INSTANCE);
 }

I am using the SPIM HAL to communicate with EM4325, this is because when I tried to integrate the spi and twi master codes (of SDK 12.3) , it was giving me garbage values in the receive buffer of the SPI, hence I tried to use the HAL. When I used the SPIM HAL, .( I have referred to the following webpage for using the HAL, my SPI Instance is 2 and TWI instance is 0 ----- https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk52.v0.9.2%2Fgroup__nrf__spim__hal.html ) 
 I tried to use the event check function but it was returning me zero values , which indicated that the SPI was not being initiated by the HAL functions 
 What is the reason for this?? I have attached the serial window output below: 
 
 Can someone please help me with a switch case code in which I can use SPI for one switch case and I2C for another ? Is it possible to do this using HAL or with the API which have been provided in SDK 12.3 itself? 
 Also, when do I know if I should use EASY DMA or not? 
 Thanking you in advance, 
 
 Kunal.