nrf52 NFC with softdevice running

Question

Hi all,
Here is my first question on this forum after many hours working with the NRF but for the first time I didn't found the answer :) 
 My problem is :
I would like to run the NFC in ISO/ICE 14443 Type A mode with t4t for reading and writing.
For now, it works alone (with some strange behaviours). I'am able to exchange in both ways (read/write) few bytes and that's exactly what I want.
The strange behaviour I mentionned above is that after few read/write sequences, it stops working and the callbak given in "nfc_t4t_setup" is no more called (only for NFC_T4T_EVENT_FIELD_OFF event). That is the first point, how could I get status of the nfc lib to monitor and, if needed, restart it? 
 The next step on which I'm struggling is that I want to use NFC with softdevice enabled and last but not least, in a low power application.
Current ble example using NFC are not relevant because it's only for paring. So I initialized NFC as usual but since I go to sleep with "sd_app_evt_wait" it doesn't wake up when I try to use NFC but the power consumption rise up to 5mA instead of 3µA before approaching the smartphone.
Is someone could help to, first find a way to use NFC properly with softdevice, and second how to wakeup properly on an event like NFC field or something ? 
 Last question : NFC callback seems to be timming sensitive (if I print debug in it) It doesn't work properly. Any advice ? 
 Thanks in advance for your help. 
 Here the code (all functions begining with Sys are calling our custom code): 
 
 
 int main(void)
{ 
 uint32_t err_code;
IS_DBG_Init();

// Set up NFC 
err_code = nfc_t4t_setup(nfc_callback, NULL);

// Start sensing NFC field 
err_code = nfc_t4t_emulation_start();

Sys_Init();

app_timer_init();
ble_stack_init(app_ble_callback);
gap_params_init(DEVICE_NAME,BLE_APPEARANCE_UNKNOWN,TX_POWER_LEVEL,STATIC_PASSKEY);
//gatt_init();
//services_init(&_app);
advertising_init(APP_ADV_INTERVAL, APP_ADV_TIMEOUT_IN_SECONDS);
//conn_params_init(); //need app_timer_init 
peer_manager_init();
advertising_start(true);

//start_scan();

while (1)
{
 if (Sys_Process())
 {
 Sys_Sleep();

 sd_app_evt_wait();

 Sys_Wakeup();
 }
}
 
 }

ispare · Accepted Answer

I think I have an answer for my first problem (nfc_lib stops working properly) :
Seems that the define HAL_NFC_ENGINEERING_BC_FTPAN_WORKAROUND helps solving the problem. It's enabled by default when using BOARD_PCA10040 but since I'm on a custom board I had to add it in my own sdk_config.h. 
 But still my second problem is there, I can't wake up from sd_app_evt_wait() with NFC field.
After many tries, if I comment my Sys_Sleep it works but what I'm doing in here is only disabling UART0 to reach 3µA consumption
CODE : 
 
 
 nrf_uart_int_disable(NRF_UART0, NRF_UART_INT_MASK_RXDRDY | NRF_UART_INT_MASK_TXDRDY | NRF_UART_INT_MASK_ERROR | NRF_UART_INT_MASK_RXTO);
 nrf_drv_common_irq_disable(nrf_drv_get_IRQn(NRF_UART0));
	nrf_uart_disable(NRF_UART0);
	nrf_uart_txrx_pins_disconnect(NRF_UART0);
 
 
 Please let me know if you have any idea on this strange behavior... 
 
 EDIT :
After many tries and research, I found that it was question of timming.
In fact, NFC lib and SoftDevice callback seems to be very sensitive.
I had a pulling printf in sys_evt_dispatch callback. Because it was printing on UART at 9600bds I think NFC timming and lib was not guaranteed so it went wrong (I suppose)...
Now all seems to be OK

nrf52 NFC with softdevice running

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