Sleep current: disabling TWI, pull-ups?

Question

I'm developing some simple wireless temperature sensors based on NRF51822s. In essence, they take a temperature measurement from a sensor over TWI, send it to a base-station using the micro_esb libraries, and then go into SYSTEM ON sleep for a period, before waking up and repeating. All without softdevice.

I've written code to do just the radio / sleeping part, which successfully puts the NRF51822 into SYSTEM ON with a current usage of ~3uA (incl. about 0.5uA for the temp sensor (also sleeping)). When I add into the code to read the temperature, the sleep mode uses ~230uA. I suspect I am not stopping and disabling the TWI correctly.

The code includes a command to disable TWI before sleeping:

NRF_TWI1->ENABLE= TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;

Should I be 'stopping' TWI first? And if so, with what command? Is it:

NRF_TWI1->TASKS_STOP=1;

I have also seen the following command used in some people's code. Is it part of the solution?

NRF_TWI1->POWER = 0;

Any advice on the correct sequence of commands to shutdown TWI (and wake it up after SYSTEM ON sleep) would be really appreciated

UPDATE: another thought, i'm also using pull-ups on some of the pins - could this cause the additional ~200uA of current drain? If so, what state should I try and leave the pins in before going into SYSTEM ON sleep if I want to minimise current usage?

main loop code below:

	while (true)
{
    ackd=false;

			// -------------- SENSE ---------------------

			twi_master_init(); 		
			// Trigger a one-shot conversion from the temperature sensor
			write_buffer[0]=1; // i.e. Configuration register
			write_buffer[1]=129; // MSB 128=OS bit, 1=SD bit
			write_buffer[2]=0; // LSB 	
			if(twi_master_transfer(TMP102_ADDRESS , write_buffer, 3, TWI_ISSUE_STOP)){
			}			

			// Wait for OS bit to be re-set to 1 to signal end of conversion
			data_buffer[0]=0;
			while (data_buffer[0] && 128!=128) {
				if (twi_master_transfer(TMP102_ADDRESS | TWI_READ_BIT, data_buffer, 2, TWI_ISSUE_STOP)) {
				}				
			}
			
			// Switch to temperature register (from config register)
			write_buffer[0]=0; // i.e. Temperature register
			write_buffer[1]=0; // MSB? 
			write_buffer[2]=0; // LSB? 	
			if(twi_master_transfer(TMP102_ADDRESS , write_buffer, 3, TWI_ISSUE_STOP)){
			}			
			
			// Read the temperature and place in the payload ready to send
			if (twi_master_transfer(TMP102_ADDRESS | TWI_READ_BIT, data_buffer, 2, TWI_ISSUE_STOP)) {
						tx_payload.data[2] = data_buffer[0];		
						tx_payload.data[3] = data_buffer[1];				
			}
			
			// Disable TWI ready for sleep
			NRF_TWI1->ENABLE= TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
			
			// -------------- TRANSMIT ---------------------
		
			if(uesb_write_tx_payload(&tx_payload) == UESB_SUCCESS)
			{
					tx_payload.data[0]++;
			}
		
			nrf_delay_ms(10);
			
						
			
			// --------------- SLEEP ------------------------
			
			// define length of sleep according to position of SW_TEST switch

			if (nrf_gpio_pin_read(SW_TEST)==0) {	
					NRF_RTC1->CC[0] = 32768;				
			}
			else
			{		
					NRF_RTC1->CC[0] = 32768*60*5;						
			}				
			
			// Start the RTC timer
			NRF_RTC1->TASKS_START = 1;

			// shut down the high-frequency clock
			NRF_CLOCK->TASKS_HFCLKSTOP = 1;
			
			awake=false;
			while(!awake)
			{
				// Enter System ON sleep mode
				__WFE();  
				// Make sure any pending events are cleared
				__SEV();
				__WFE();                
			}
				
			// Stop and clear the RTC timer
			NRF_RTC1->TASKS_STOP = 1;
			NRF_RTC1->TASKS_CLEAR = 1;	

			// Restart the hi-frequency clock
			NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
			NRF_CLOCK->TASKS_HFCLKSTART = 1;
			while(NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);	
			
			
}