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Having trouble reading data in SSP0_MISO in a LPC1857 part

Question asked by Alejandro Celery on Oct 17, 2017
Latest reply on Oct 26, 2017 by Kerry Zhou


I'm having trouble reading an SPI peripheral (an SC16IS740) using a LPC1857.

The problem is that when I read the DR register, it ALWAYS returns 0xFF.

I am using pin P3_7 in function 2 with the following configuration:



I read data using:

uint8_t r;

Chip_SSP_ReadFrames_Blocking( LPC_SSP0, &r, 1 );


When I debug my code the Chip_SSP_ReadFrames_Blocking call I see the proper execution flow:

Chip_SSP_GetStatus(pSSP, SSP_STAT_RNE) returns true before I read the received frame and I see the status RNE status flag go to 0 after the read.

I have checked with a scope that the P3_7 line has the correct reply from the device when there is no data: 0x60.


I have tried the exact same code on SSP1 and it works perfectly.


It seems like I am making a mistake when configuring the SSP0 device or that there is something missing in the documentation. Perhaps an interaction with the boot procedure (since SSP0 is a possible boot code source)? I checked everything that I could think of, please help me with these problem.


Best regards,