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SPI Master Slave Query

Question asked by sudhir prabhu on Mar 11, 2013

Hi All,


I am using K60 Kinetis MCU in SPI Slave mode, i will be interfacing this with Microprocessor unit which acts as SPI master.

I have initialized SS1:SPI Slave_LDD using Processor Expert CPHA=1, CPHA=0 CS = ACTIVE LOW.

Attached Processor Expert file for SPI configuration reference


Slave Side

After calling the SS1_Init(NULL);

Data which i will be sending to SPI Master is sent to TXFIFO using following instruction followed by GPIO interrupt to Master


From the debugg mode i was able to see SPI2_TXFR0 buffer filled with value 0x0A


/*Interrupt Generation to Master CPU */

GPIO2_SetFieldValue(Led1Data, INTR, 0X1);

GPIO2_SetFieldValue(Led1Data, INTR, 0X0);

Master Side

SPI Master on receiving INTR initiates SPI read by sending dummy clock & de-asserting CS line depending on number of bytes i have to read. But i do not see any activity on MISO line and remains LOW. SPI master is configured to same CPHA & CPOL as that of slave

How do i read the data using my SPI Master from SLAVE's TX buffer? Does SPI master has to make any write before slave sends any data?



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