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LPC54114 SPI can transfer data, but SSEL keep high

Question asked by Yu-Cheng Chen on Jul 14, 2019
Latest reply on Jul 15, 2019 by Felipe García

I download these two example file from https://mcuxpresso.nxp.com/en/example-projects?uvid=187339 : 

 

spi_half_duplex_polling_master

spi_polling_b2b_transfer_master

 

but in both project, the SSEL port seems to keep high, even in transmiting data period.  I didn't connect the slave.

 

my initial setting are : (not changed)

void SPI_MasterGetDefaultConfig(spi_master_config_t *config)
{
assert(NULL != config);

/* Initializes the configure structure to zero. */
memset(config, 0, sizeof(*config));

config->enableLoopback = false;
config->enableMaster = true;
config->polarity = kSPI_ClockPolarityActiveHigh;//kSPI_ClockPolarityActiveHigh: 0 kSPI_ClockPolarityActiveLow :1
config->phase = kSPI_ClockPhaseFirstEdge; //kSPI_ClockPhaseFirstEdge : 0 kSPI_ClockPhaseSecondEdge :1
config->direction = kSPI_MsbFirst;
config->baudRate_Bps = 500000U;
config->dataWidth = kSPI_Data8Bits;
config->sselNum = kSPI_Ssel0;
config->txWatermark = kSPI_TxFifo0;
config->rxWatermark = kSPI_RxFifo1;
config->sselPol = kSPI_SpolActiveAllLow;
config->delayConfig.preDelay = 0U;
config->delayConfig.postDelay = 0U;
config->delayConfig.frameDelay = 0U;
config->delayConfig.transferDelay = 0U;
}

 

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