TM4C123GH6PM: SSI communication on 1 board

Hi cb1,

Thanks for your replay. I have used SSI0 as a slave, SSI1  as a master and PD6 as SS signal.

I have connected the wiring as the following:

SS signal from PD6 to PA3(SS pin of the slave)

PD0 to PA2 (clock pins on master and slave)

PD3 to PA4 (TX of master to RX of slave)

PD2 to PA5 (RX of master to TX of slave)

but when i write to Data Register of master trying to send byte its value doesn't change!

and no transmitting occur

could you please help ? what should i do to have successful data transfer?

here is the initialization code and the main

void SSI0_Init(void){

    // settings for TX, RX, SS, CLK in GPIO PORTA
    SYSCTL_RCGCSSI_R |= 0x01 ;      // clock on SSI0 module
    SYSCTL_RCGCGPIO_R |= 0x01 ;     // clock on PORTA
    GPIO_PORTA_AFSEL_R |= 0x3c ;    // alt. function for PORTA 2, 3, 4, 5
    GPIO_PORTA_PCTL_R |= 0x00222200;
    GPIO_PORTA_DEN_R |= 0x3c ;      // digital enable

    // settings of SSI0 module
    SSI0_CR1_R = 0 ;                // disable during configuration
    SSI0_CC_R = 0 ;                 // system clock
    SSI0_CPSR_R = 2 ;               // prescaler div by 2
    SSI0_CR0_R |= 0x07 ;            // 8MHZ, SPI mode, 8 bit frame
    SSI0_CR1_R |= 0x04 ;            // set as a slave
    SSI0_CR1_R |= 0x02 ;            // enable
}

void SSI1_Init(void){

    // settings for TX, RX, SS, CLK in GPIO PORTA
    SYSCTL_RCGCSSI_R |= 0x02 ;      // clock on SSI1 module
    SYSCTL_RCGCGPIO_R |= 0x08 ;     // clock on PORTD
    GPIO_PORTD_AFSEL_R |= 0x0F ;    // alt. function for PORTD 0,1,2,3
    GPIO_PORTD_PCTL_R |= 0x02;
    GPIO_PORTD_DEN_R |= 0x0F ;      // digital enable

    // settings for PD6 as SS signal
    GPIO_PORTD_DIR_R |= 0x40 ;      // PD6 output
    GPIO_PORTD_DEN_R |= 0x40 ;      // digital enable PD6
    GPIO_PORTD_DATA_R |= 0x40 ;     // keep SS idle high

    // settings of SSI1 module
    SSI1_CR1_R = 0 ;                // disable during configuration
    SSI1_CC_R = 0 ;                 // system clock
    SSI1_CPSR_R = 2 ;               // prescaler div by 2
    SSI1_CR0_R |= 0x07 ;            // 8MHZ, SPI mode, 8 bit frame
    SSI1_CR1_R = 0x00 ;             // set as a master
    SSI1_CR1_R |= 0x02 ;            // enable
}

int main(){
    SSI0_Init();
    SSI1_Init();

    while(1){
    // set ss low
    GPIO_PORTD_DATA_R &= ~0x40 ;            // ss low
    while ((SSI1_SR_R & 0x02) == 0 ){}      //wait till fifo not full
    SSI1_DR_R = 0xff ;                      // send char a
    while (SSI1_SR_R & 0x10){}              // wait for TX complete
    GPIO_PORTD_DATA_R |= 0x40 ;             // ss high

    uint32_t data ;
    while ((SSI0_SR_R & 0x04) == 0){}       // wait for not empty fifo flag
    data = SSI0_DR_R ;                      // data reading
    int i = data ;
    }
}

Regards,

Sarea

Thank you, my friend.

May I (again) challenge your belief that (someway) "Starting w/DRM" ... "Makes sure of strong understanding?"

If such "strong understanding" would result - would not your code, "Perform to full expectation?"       Alas - it does not (in fact - does not (even) "come close") - and the clock ticks - and strong understanding proves, "Nowhere to be seen!"        (Do not ALL "facts in evidence" - point in this inescapable direction?)

May I suggest a "hybrid method" (employed by our intern & new staff hires) which includes "Joint Use" of the API (to select the most appropriate API functions - as the project requires) and (then) a serious visit to the MCU Manual's "Register Presentation" - to add further "light" to the API's "broader brush!"

It is expected that this "hybrid method" will, "Speed, Ease & Enhance" your learning - leading to, "mastery!"        And FAR FASTER & MORE EFFICIENTLY than, "DRM Alone!"     (your visit here - courtesy of the "Failed DRM Only approach" - clearly suggests such - does it not?)

Bob,

I have told my heart to, "Be still!"     Much thanks for your kind "#LIKE" - along w/your agreement with the "Speeded, Eased & Enhanced" understanding this "Hybrid" method insures.    (API selective use - followed by the proper review of,  "Registers in play.")

"DRM-Only" proponents, "Shut  their eyes" to the MAJOR GAINS which such "Hybrid Method" provides!       (i.e. Hybrid extracts the "best" features, advantages, & insights - from each coding method.)     The API is "world-class!"     Its: "depth, breadth and ability to remarkably, "Speed & Ease" code development" proves "irresistible" - rejecting its use borders upon, "foolhardy!" 

Such "Hybrid" election (proper mix of the API followed by Register review)  proves (near) ideal - even if - and especially if - "missed"  (possibly deliberately) by those with, "Shut eyes!"