Other Parts Discussed in Thread: TM4C1294NCPDT
Tool/software: TI-RTOS
In a TM4C1294NCPDT microcontroller + TI-RTOS enviroment , in order to enable an external memory before the C runtime initialization, we are using a "reset function" as below in .cfg:
var Startup = xdc.useModule('xdc.runtime.Startup');
var Reset = xdc.useModule("xdc.runtime.Reset");
Reset.fxns[Reset.fxns.length++] = "&sdram_init";
That works fine. The problem occurs when sdram_init function calls the GPIO functions such as "SysCtlPeripheralEnable", " GPIOPinConfigure" etc , it generates an exception that halt the program.
void sdram_init(void)
{
SysCtlPeripheralEnable(SYSCTL_PERIPH_EPI0); /**< habilita EPI0 0xf0001000 */
GPIOPinConfigure(GPIO_PH0_EPI0S0); /**< 29| PH0|EPI0S0 */
GPIOPinConfigure(GPIO_PH1_EPI0S1); /**< 30| PH1|EPI0S1 */
GPIOPinConfigure(GPIO_PH2_EPI0S2); /**< 31| PH2|EPI0S2 */
GPIOPinConfigure(GPIO_PH3_EPI0S3); /**< 32| PH3|EPI0S3 */
GPIOPinTypeEPI(GPIO_PORTH_BASE, EPI_PORTH_PINS); /**< inicializa porta H como EPI */
GPIOPinConfigure(GPIO_PC7_EPI0S4); /**< 22 | PC7 | EPI0S4 */
GPIOPinConfigure(GPIO_PC6_EPI0S5); /**< 23 | PC6 | EPI0S5 */
GPIOPinConfigure(GPIO_PC5_EPI0S6); /**< 24 | PC5 | EPI0S6 */
GPIOPinConfigure(GPIO_PC4_EPI0S7); /**< 25 | PC4 | EPI0S7 */
GPIOPinTypeEPI(GPIO_PORTC_BASE, EPI_PORTC_PINS); /**< inicializa porta C como EPI */
GPIOPinConfigure(GPIO_PA6_EPI0S8); /**< 40 | PA6 | EPI0S8 */
GPIOPinConfigure(GPIO_PA7_EPI0S9); /**< 41 | PA7 | EPI0S9 */
GPIOPinTypeEPI(GPIO_PORTA_BASE, EPI_PORTA_PINS); /**< inicializa porta A como EPI */
GPIOPinConfigure(GPIO_PG1_EPI0S10); /**< 50 | PG1 | EPI0S10 */
GPIOPinConfigure(GPIO_PG0_EPI0S11); /**< 49 | PG0 | EPI0S11 */
GPIOPinTypeEPI(GPIO_PORTG_BASE, EPI_PORTG_PINS); /**< inicializa porta G como EPI */
GPIOPinConfigure(GPIO_PM3_EPI0S12); /**< 75 | PM3 | EPI0S12 */
GPIOPinConfigure(GPIO_PM2_EPI0S13); /**< 76 | PM2 | EPI0S13 */
GPIOPinConfigure(GPIO_PM1_EPI0S14); /**< 77 | PM1 | EPI0S14 */
GPIOPinConfigure(GPIO_PM0_EPI0S15); /**< 78 | PM0 | EPI0S15 */
GPIOPinTypeEPI(GPIO_PORTM_BASE, EPI_PORTM_PINS); /**< inicializa porta M como EPI */
GPIOPinConfigure(GPIO_PL0_EPI0S16); /**< 81 | PL0 | EPI0S16 */
GPIOPinConfigure(GPIO_PL1_EPI0S17); /**< 82 | PL1 | EPI0S17 */
GPIOPinConfigure(GPIO_PL2_EPI0S18); /**< 83 | PL2 | EPI0S18 */
GPIOPinConfigure(GPIO_PL3_EPI0S19); /**< 84 | PL3 | EPI0S19 */
GPIOPinTypeEPI(GPIO_PORTL_BASE, EPI_PORTL_PINS); /**< inicializa porta L como EPI */
GPIOPinConfigure(GPIO_PB3_EPI0S28); /**< 92 | PB3 | EPI0S28 */
GPIOPinTypeEPI(GPIO_PORTB_BASE, EPI_PORTB_PINS); /**< inicializa porta B como EPI */
GPIOPinConfigure(GPIO_PN2_EPI0S29); /**< 109 | PN2 | EPI0S29 */
GPIOPinConfigure(GPIO_PN3_EPI0S30); /**< 110 | PN3 | EPI0S30 */
GPIOPinTypeEPI(GPIO_PORTN_BASE, EPI_PORTN_PINS); /**< inicializa porta N como EPI */
GPIOPinConfigure(GPIO_PK5_EPI0S31); /**< 62 | PK5 | EPI0S31 */
GPIOPinTypeEPI(GPIO_PORTK_BASE, EPI_PORTK_PINS); /**< inicializa porta K como EPI */
EPIDividerSet(EPI0_BASE, 1); /**< configura base de clock de EPI */
EPIModeSet(EPI0_BASE, EPI_MODE_SDRAM); /**< configura EPI como SDRAM */
EPIConfigSDRAMSet(EPI0_BASE, ( EPI_SDRAM_CORE_FREQ_50_100 |
EPI_SDRAM_FULL_POWER | EPI_SDRAM_SIZE_64MBIT), 468); /**< configura clock */
EPIAddressMapSet(EPI0_BASE, EPI_ADDR_RAM_SIZE_256MB | EPI_ADDR_RAM_BASE_6); /**< configura tamanho máximo da sdram */
while(HWREG(EPI0_BASE + EPI_O_STAT) & EPI_STAT_INITSEQ){_nop();} /**< aguarda status de configuração dos registradores */
}
That sequence of initialization works well when sdram_init is called directly from main, but we need to do that before C Runtime initialization for use it for static variables. with apropriate linker settings
I ask if these "GPIO" functions can not be called before C Runtime initialization ?
Is there an alternative method to initializing the pins to enable external memory before C Runtime initialization .
