Hello everyone,
I've been stuck on this issue for a while and would greatly appreciate any insights you might have.
Hardware:
- Okdo e1 with LPC55S69 MCU
- NXP Flex Antenna Class 6 with NTAG I2C 2k Plus (NT3H2111_2211)
Software:
- LPCXpresso55S69_NTAG_I2C_Explorer_Blink (modified for passthrough mode)
I'm trying to use the NTAG's passthrough mode to send data from a phone to the MCU.
The size of the data is larger than the SRAM capacity.
I've configured the NC_REG as follows:
00111101b
NFCS_I2C_RST_ON_OFF: 0b (Disabled)
PTHRU_ON_OFF: 0b (Disabled but enabled later in the code)
FD_OFF: 11b
FD_ON: 11b
SRAM_MIRROR_ON_OFF: 0b (Disabled)
TRANSFER_DIR: 1b (RF to I2C)
Process I go through into the code :
- Check NS_REG for RF field presence (last bit).
- If detected, enable passthrough mode (PTHRU_ON_OFF = 1b).
- Phone detects the field and writes data to the NTAG's SRAM.
- Check NS_REG for SRAM_I2C_READY bit.
- If set, read the data from SRAM via I2C.
Passthrough itself seems to be working for the first two iterations (data sent and received correctly).
The loop stops after 2 iterations. The I2C_LOCKED, SRAM_I2C_READY bits reset to 0, and the RF_LOCKED bit goes back to 1, stoping communication. Therefore, the rest of the data is not sent nor received.
Here is the part of the example I modified for this:
int main(void) {
/* Init Board hardware. */
Setup();
uint8_t ns_reg = 0; // Session register
uint8_t FD = 1;
BOOL status = FALSE;
unsigned char response[64];
/* Configuration register NC_REG setup for operation in passthrough mode. */
// Set NFCS_I2C_RST_ON_OFF
NTAG_SetI2CRstOnOff(ntag_handle, FALSE);
/* The PTHRU_ON_OFF bit is handled later in the code */
// Set FD_ON bits and FD_OFF bits to 11b corresponding to passthrough operation.
NTAG_SetFDOnFunction(ntag_handle, DATA_READY_BY_I2C_OR_DATA_READ_BY_RF_11b);
NTAG_SetFDOffFunction(ntag_handle,I2C_LAST_DATA_READ_OR_WRITTEN_OR_RF_SWITCHED_OFF_11b );
// Set SRAM_MIRROR_ON_OFF bit to 0b to disable SRAM Mirror feature
NTAG_SetSRAMMirrorOnOff(ntag_handle, FALSE);
// Set TRANSFER_DIR bit to 1b for passtrough from NFC to I2C.
NTAG_SetTransferDir(ntag_handle, RF_TO_I2C);
// Main Loop
while (1) {
// Read NTAG I2C session registers. The last bit of NS_REG indicates whether RF field is detected
status = NFC_ReadRegister(ntag_handle, NTAG_MEM_OFFSET_NS_REG, &ns_reg);
if (status) {
PRINTF("\r\nCommunication Failed!");
}
while ((ns_reg & NTAG_NS_REG_MASK_RF_FIELD_PRESENT)) {
// Field detection handler
if (FD) {
FD = 0;
PRINTF("\r\nFIELD DETECTED!");
NTAG_SetPthruOnOff(ntag_handle, TRUE);
}
while((ns_reg & NTAG_NS_REG_MASK_SRAM_I2C_READY)) {
// Read SRAM content
status = NTAG_ReadBytes(ntag_handle, NTAG_MEM_ADDR_START_SRAM, response, NTAG_MEM_SRAM_SIZE);
if(status) PRINTF("\r\nREADER NOT READING");
// we check again for SRAM_i2c_READY
NTAG_ReadRegister(ntag_handle, NTAG_MEM_OFFSET_NS_REG, &ns_reg);
}
// we check again if RF field is available
NTAG_ReadRegister(ntag_handle, NTAG_MEM_OFFSET_NS_REG, &ns_reg);
}
if (!FD) {
PRINTF("\r\nFIELD LOST!\r\n");
// Reset field detection status.
FD = 1;
}
}
}
